Solar Hot Water Part V: Insulation

A much underappreciated  part of making a solar hot water system efficient is properly insulating it to reduce parasitic losses. There are two aspects to this:

1. Properly insulating the pipes carrying the hot water and the heat transfer fluid from the solar collector.
   
2. Ensuring that the solar tank and any backup storage (the gas fired tank in my case) are sufficiently insulated to reduce loss during water storage.
   

The contractor did a fine job on the pipes carrying the heat transfer fluid outside leading from the solar collector to the inside of the house. This is a particularly crucial area, because if the air temperature is low during the day the losses in this section can be really high. But for the pipes on the inside, if you take a look at my previous post on installation (which you'll find here), you can see that the contractor sort of insulated the pipes on the inside. The black rubber you see around the pipes in some of the pictures is pipe insulation. The contractor did an OK job with most of the pipes except around the gas fired hot water heater. The pressure relief valve pipe and the hot water pipe leading into the house were not insulated and radiating heat. Also, at places where the pipes had a bend, the black rubber pipe insulation stopped and left small areas of copper exposed that could radiate heat. Getting pipe insulation right takes a lot of time and effort, something most contractors don't want to do (otherwise they would have to charge you for it).

So I spent some time doing the pipe insulation myself. I installed the black rubber insulation around all the pipes which the contractor forgot, and sprayed some high temperature foam insulation around the pipe corners, and around the connections between the pumping station and the feed-in lines. Here's a picture of how the pipes look in the ground floor gas-fired hot water heater closet:

 The blobs of pink matter you see hanging down from the pipes where a corner is are the high temperature foam. Note that this is not the standard polyurethane foam that you can get for insulation at the hardware store, this is foam which is rated for installing, for example, between floors in apartment buildings to help retard the progress of a fire. It won't stop a fire, since it is organic and will ultimately burn, but it is rated to a much higher temperature than the standard, white polyurethane foam that's used for sealing around doors and windows. It's available at Home Depot, and the important distinguishing factor is, as you can see, that it is pink. I used high temperature foam because the temperatures around the pump station (which you can't see here) and around the furnace flue which leads up through the closet can get pretty high, maybe around 180F, which might cause the normal foam to get soft, if not melt. Finally, the white blobs you see are tags indicating what each of the pipes do (sorry, the picture  is a  little out of focus because the shutter was open for a long time and my camera doesn't have image stabilization).

The second aspect is the tank. The Superstor comes with 1.5" of closed cell foam insulation, and they claim that it loses around 0.5F per hour (as we will see in a later post, this is optimistic at best). To my mind, that is simply not enough insulation. My Hot Springs hot tub has around 6" of closed cell foam, and it loses maybe 2F overnight if I turn the temperature down to 80F after having it up around 102F, and that is outside where the ambient temperature in winter is a lot lower than inside the house. I think the reason they don't add more insulation to the Superstor is that it would make the tank's diameter bigger, and, of course it would make the tank even more expensive (the Superstor is pretty expensive as is).

My first plan was to spray the tank with closed cell foam before the contractor installed it, but a quick check with the city building inspector indicated that they would probably not approve the project if the tank was coated with closed cell foam. I then came up with the idea to take radiant barrier insulation made from aluminum foil and plastic bubble wrap and make a form the size of the tank, then spray it with closed cell foam to make a kind of jacket. So I tried that (sorry, no pictures) but the result was too rigid once it had dried and I couldn't get it into the narrow space between the tank and the wall.

Since I had some radiant barrier left, I decided to wrap both tanks in radiant barrier insulation as a start. I did this work in summer right after they installed the system, and the solar tank was radiating heat strongly, a bad sign. I did the wrapping in two phases, first the left side then the more complicated right side around all the connections. Here's a picture of what the Superstor looks like when it is completely wrapped in radiant barrier insulation:

One issue was what kind of tape to use. Standard duct tape probably won't work because the glue will melt from the high temperatures in summer. I first tried an aluminum tape from 3M that is specifically for furnace flues and other high temperature applications. It wasn't ideal, it was stiff and didn't adhere unless you really pressed it, also, it had sharp edges, but it sort of worked, although some places that weren't pressed hard enough came loose. I then found a similar tape from Nashua which sticks a lot better and doesn't require strong pressing to bind.

After I finished the radiant barrier job, I discovered that a new line of high temperature duct tape had been introduced on the market. I used some that on the R-13 fiberglass blanket which I wrapped around both tanks on top of the radiant barrier. You can see that on the bottom of the picture above of the gas fired tank. Here's what the Superstor looks like nicely clothed in its new fiberglass blanket:

The gray stripes around the tank are where I taped together the R-13 batts.

One question that might come up is: why not used one of the premade vinyl insulation jackets that are commercially available? I thought about this, but there are a number of problems. First, I couldn't get a jacket big enough for the Superstor. It is 60" tall, much larger than a standard 40 gallon gas or electric domestic hot water heater. Second, they only provide something like R-7 of insulation. I now have R-13 with maybe R-7 or so of radiant barrier. Finally, vinyl is not a good material to have around the house, especially around hot areas where chemicals can outgas. I looked around for a jacket that didn't have a vinyl skin but could not find any.

In the next post, I'll talk a bit about how the system is performing, and provide some data about how well my insulating treatments have worked.

Solar Hot Water IV: The Installation Experience

Chris and Justin from Sunwater Solar came by and had a look at our house. We decided to put the collectors on the east side since the west side is occupied by the solar PV. The east side gets sun primarily in the morning, but since the solar PV is higher value in the afternoon (about 3x the tariff other times), having it on the west side is a better deal. So it made sense to keep the remaining space on the west side, about enough for another 3 PV panels, for solar PV if we decide to add some in the future.

Then came the question of where to put the tank. We initially considered putting it in a small house next to the sauna, or maybe next to the fireplace pod that sticks out from the house, but ultimately we decided to repurpose the cold air return for the forced air heating. We had the forced air heating taken out a couple years ago and put in hydronic floor heating, so we didn't need the space any more. It is on the second floor in the hallway. The space consisted of a plenium with a large grate on the front, which led into the downstairs furnace room. When we had the hydronic furnace installed in the furnace room, the plenium was blocked off from downstairs. As we discovered when we opened up the space and removed the plenium, the flue from the furnace and the gas fired hot water heater in the downstairs mechanical room ran up the middle. We had a bit of work to do on the space.

Point to note when planning a solar hot water system: be sure to include enough time and money for upgrading the space where you plan to put the tank and the pump station if you are not going to use your existing tank.

Sunwater doesn't do the kind of drywall and carpentry work needed to modify the space, so we asked a friend of ours who is a contractor, Tim Hmelar (check out his new business, Purple Coupon) to do it. Tim is the most reliable contractor I know, his work always comes in on time and at or under budget. Together with Tim's brother Frank, who sometimes helps him on jobs, we decided to put a door in the side of the space and a hatch where the grate for the cold air return was located. The pump station then could be installed in the upper space on the inside of the hatch, with the tank below it. Just under the hatchway, we decided to put a platform on which someone could sit while servicing the pump station.

Because the flue ran up the middle of the space, Tim and Frank had to move it to the back. You can see the new location before the platform was installed:

The black pipe is the vent from the bathroom, which is on the wall immediately to the right of the flue.

Here's a view of the bottom where a plywood floor was installed to support the tank:

One issue we ran up against was what to put on the inside walls. By code, if there was any loose wiring, we needed to have some kind of protection in place to keep someone from accidentally grabbing the wires. But the amount of space in the closet was pretty tight, especially since I wanted to wrap the tanks in additional insulation. The normal thickness of drywall is 1/2" but it turns out you can also get 1/4" drywall, which is what we ended up using. This gave us another 1/2" of space. In addition to that, Tim put 6" of closed cell foam insulation on the roof and at least 3" on the walls of the closet, to reduce the amount of heat transfer into the house in the summer, when the tank can get up to 175F.

The downstairs gas heater tank looks pretty normal as you can see from this picture:

The insulating blanket isn't doing much good since it is not tight against the tank, and, by the way, the outer skin is vinyl, which is quite unhealthy. But we were were going to change all that.

The guy Sunwater sent to do the installation was an older tradesman, quite pleasant to talk with, but I began to have some suspicions about his competence almost immediately. One day I came home from work after the tank had been installed, and found that he had connected the feed lines from the collector to the top heat exchanger instead of the bottom. Now, heat rises, so this configuration would have caused the tank to stratify with the incoming cold water line injecting cold water on the bottom and the hot water on the top, where the water outlet for the domestic hot water is. I called him up and made him change the plumbing.

In the picture below, you can see the bottom of the fully installed Superstor tank, where most of the interesting stuff is happening (there's some on the top too but not as much):

The two lines in the back with the black foam around them are the feed lines from the collector, going through the correct lower heat exchanger. The corrugated line is the pressure overflow from the tank, the line it is connected to is the pressure overflow coming down from the expansion tank and pump station in the upper chamber above the platform. The line entering the tank is the cold water input from the house and ultimately the main. The other line in the elbow on the right side is the hot water running to the gas hot water tank downstairs, you can't see the pipe running down from the top of the tank where the hot water outlet is because it is behind the door frame. There is also another pipe running across behind the cold water input, connected to the pan, that's also an overflow pipe to the drain. In the back is the furnace and gas hot water heater flue.

Below you can see the internals of the pump station in the upper chamber before the cover was put on:

The brass colored cylinder is the pump, three gauges on the front provide information about the temperature (to and from collector) and pressure in the feedlines. The feedlines coming from the collector through the outer wall of the house are on the top. The blue wire is the power cord (110v, 15 amp, we also had Tim install a plug for it). Here's what the pump station looks like when the cover is on:

And here you can see the white expansion tank:

The grey wire in the background is the sensor cable from the collector, the corrugated line is the pressure overflow from the expansion tank to the pipe going to the drain downstairs, and of course the ubiquitous flue.

Since the solar hot water acts as a preheater for the gas heated tank downstairs, it needed to be plumbed into the gas tank. Here's a picture of what that now looks like:

The grey knob you see in the middle is the mixing valve. It is where the hot water from the tank is mixed with cold water to keep the domestic hot water below 120F. Above that temperature, scalding is possible. As for the rest, the grey steel line on the left is the pressure overflow, the horizontal  line with the red lever on the  bottom is the hot line from upstairs, feeding into where the cold line would normally go (for preheating), the horizontal line on the top is the cold going to the tank upstairs. The grey knob is where the domestic hot water comes out of the gas tank. In the back on the right is a feed line for the hydronic boiler, from the cold line, and a cold line that goes into the tank, with the red lever now in the off position. Switching the front red lever to off and the back to on causes the solar tank to be cut out of the loop. Unfortunately, there is no way to switch the gas tank out of the loop (more on this in a later post).

Charging the collector feedlines with the heat transfer fluid requires a very specific pressure adjustment to match the height difference between the collector and the expansion tank, and also any air in the feedlines must be purged or the bubbles will cause a lock and prevent pumping. After the installer charged it up the first time, the tank didn't seem to be getting any heat. It turned out that the pump wasn't on because he had forgotten to turn on the power switch! He came and fixed that, but then the pumps were really loud and there still didn't seem to be any heat getting into the tank. So he came back again: he had forgotten to bleed the air out and so the lines were locked. When I checked the pressure after he finished, it turned out he had way overpressurized the lines, as if there were 10 vertical feet or so between the collector and the expansion tank instead of the 2-3 feet there is. By this time I had had enough of this guy. When I discovered that the unions on the tank and in the pumping station were leaking hot glycol (and copiously at that), I called Justin and told him I wanted somebody who knew what they were doing put on the project.

Justin was very accommodating and worked with me to get the problems fixed (also, I didn't send him his last payment until he did, just to make sure). But it took another month before we could get the unions properly fixed. Justin sent one of his best guys over, and he first re-soldered the unions on the tank. But he couldn't get the pump station unions tight. It turns out they have a kind of pressure coupling which seals when tightened, but when overtightened, leaks. So he had to send his very best guy to come and cut through the pressure couplings. One slip and they would have had to reinstall the entire feedline set from the collector again (or, at least, a substantial part of it)! But thankfully he managed to cut just precisely right and they reinstalled the pressure couplings. Both sets of unions now looked solid.

Despite the fact that we had such problems with the installation, I don't hold it against Justin, and I would still recommend Sunwater. As it turns out, the installer had only been working for Sunwater for a few months, whereas the other two guys had been working with Justin for years. I've been in this situation myself: you hire someone with a great resume and they turn out to be a dud (or, even worse, they falsified the resume and don't know the basics of the job). So I didn't hold it against him. Justin really tried to get the system properly fixed, and ultimately did fix it to my satisfaction. However, this does point up a problem with the whole area of residential green energy and energy efficiency remodeling: many contractors and/or the people working for them don't have a clue. So they often do things, especially when it comes to insulation or weatherizing, that are ineffective or, in this case, downright harmful.

Point to note when planning a solar hot water system:be sure you understand how the system is supposed to work and what is needed in terms of insulation to make it efficient, and make sure the contractor does the work necessary to ensure it works properly.

Note to President Obama: "Cash for Caukers" won't work if the caukers don't know how to wield a cauking gun so they can properly insulate. Most people in construction in the US are in the business because they can't do any other work. Unlike Europe, where trades require a substantial amount of technical training, and where the trades have over the last 10 years upgraded their members' training through in service education to address energy conservation and green energy equipment installation, the assumption in the US seems to be that anybody can do this work without any training. If this kind of attitude goes into "Cash for Caukers" the resulting weatherization is not going to save energy, it will be a colossal waste of money. I'd recommend to the Congress if they want to do "Cash for Caukers" that they should budget enough that any contractor who plans to participate must take a 6 month course in energy efficiency building so they understand what they are doing. And - just to be on the safe side and avoid fraud - have people trained to inspect the job periodically the way building inspectors do, since most inspectors don't have the training to spot improperly installed green energy devices or ineffective insulation either.

Solar Hot Water Part III: Our System Architecture

As mentioned in the previous post, the system architecture we decided on was to have the cold water from the city main feed into the solar tank, preheat with solar, and then feed into the gas-fired hot water tank. In addition, we decided to get a solar tank with a second heat exchanger coil. This would allow an external boiler, for example a geothermal heat pump or efficient closed combustion gas boiler, to be substituted for the gas-fired tank in the future if we wanted.

Here is a brief description of the system we had installed:

Collector: Schueco Slim Line II-80
Tank: Superstor SB 80 gallon w. backup heat exchanger
Balance of system: Pumping station PS 1.3 from Schueco, expansion tank, DeltaSol BS thermostatic control, etc. was part of the Schueco package

Normally, the Schueco system comes with a double walled steel tank from Rheem, but we dropped that and ordered the Superstor instead.

We decided on Schueco instead of another collector such as Heliodyne because the Schueco collectors are designed to force the heat transfer fluid out of the collector and into the expansion tank when the collector stagnates and begins to overheat. The water in the heat transfer fluid flashes to steam increasing the pressure and forcing the fluid into the expansion tank. This keeps the propylene glycol in the fluid from cooking, increasing the lifetime of the fluid. I've heard anecdotally that Schueco has tested their collectors for up to ten years without needing to change the fluid.

The diagram below shows the system in schematic form (note: the diagram is edited from the Schueco installation manual and is copyright Schueco, used here under the Fair Use exemption):

 The diagram shows the hot water coming into the solar tank, being heated by the solar heat exchanger and flowing from there into the gas hot water tank. The gas hot water tank heats it further if necessary then the water goes into the house. There is a temperature control valve on the house side of the gas hot water tank to keep domestic hot water temperature below 120F, since hotter temperatures are dangerous and can scald. The hot and cold heat transfer fluid flow to and from the collector is shown above the pump station.

The numbered items on the diagram are the following:

1. The Schueco Slim Line II-80 collectors (2).
   
2. The expansion tank and overflow hose. If the pressure gets too great and while filling the system, glycol can run out into the drain through the overflow hose.
3. The Schueco PS 1.3 pump station.
4. The Superstor tank. The bottom heat exchanger is connected to the pump station, the top exchanger is not connected to anything at this point.
5. The DataSol BS thermostatic control. It compares the collector temperature at T1 and the tank temperature at T4 and only turns the pump on if the collector temperature is hotter than the tank, and turns the pump off if the tank temperature exceeds 180F.
6. The existing hot water backup tank.

There are also two pressure release pipes coming out of the solar tank and the gas hot water tank that are not shown on the diagram, these are standard for hot water systems to avoid having the tank overpressurize  and rupture.

Spark Plugs

Last year I saw some information on the Internet about a new kind of spark plug that supposedly increased gas mileage, and also increased torque and power. Much as I love it, our 2002 Prius is no speed daemon, especially when you are trying to merge onto the freeway. In fact, I would say it is somewhat underpowered. The plugs are called Pulstar™ from Enerplus. They are pricey: $25 compared to maybe $1.50 for normal plugs. Being an early adopter at heart, I thought I would give them a try, so I ordered a set of four.

The plugs worked great initially. Torque and power was much better, and the gas mileage rose by another 2 mpg. I was really happy. Then, around 6 months later, the gas mileage started slowly dropping - from 46.6 to 44.3. Since that was the transition from winter to summer, I took it to be the normal Prius variation in mileage with temperature. Anybody who has a Prius notices this - you get much better mileage in summer than winter because the car warms up sooner and so the engine shuts off sooner.

On Wed., I was driving downtown when the engine suddenly began to chug. I thought it was an earthquake or something, Toyotas are usually reliable. Then the check engine light began flashing - whooo! whoo! red alert! That got me concerned. Fortunately, I was only a couple of blocks from my mechanic, so I slowly nursed the car to the garage and left it there for repair the next day.

The mechanic called me around noon the next day with the news. Apparently, the plugs had fouled and shorted out the ignition coil. He was really surprised, since the Prius comes with iridium plugs that supposedly last for 120,000 mi. I had the Pulstar™ plugs in for less than a year.

I asked him to give me the plugs, which he did, then today I called up Enerpulse and asked them to make good on their warranty, which is (quoting directly from their Web page):

Guarantee
We offer a 4-point guarantee on Pulstar™ Pulse Plugs. This means:
1) You can return the Pulstar™ pulse plugs for any reason within 30 days, no questions asked.
2) Pulstar™ pulse plugs will not harm your engine.
3) Pulstar™ pulse plugs will last 50,000 miles.
4) Pulstar™ pulse plugs will not void your warranty.

Near as I can tell, this incident violated at least 2) and possibly 3) if the plug that fouled shorted itself out too.

Enerpulse told me that I had to send the plugs and the ignition coil back to them, along with the bill from the mechanic and a letter explaining the situation. Fair enough. I guess they need to have the evidence before they are willing to cough up any money, since people do cheat.

I called the mechanic up again and asked if he had the coil. He did, so I picked it up today.

We will see whether they are as good as their word. Stay tuned.

Solar Hot Water Part II: Background on Our System

I've been researching solar hot water systems for a number of years, waiting until the state of California instituted a subsidy. Unfortunately, a trial program in San Diego only netted double digit installations, indicating a general lack of interest in solar hot water (more on this in a later post). That and the sorry state of California's finances caused the state to indefinitely postpone any subsidy for solar hot water. For that, this year the Feds put in place a really nice 30% tax rebate (not a deduction, a rebate) on alternative energy. The rebate includes the cost of everything involved in installation, not just the equipment. So this spring we decided to take the plunge, and I began looking around for solar hot water installers.

One problem is that there are very few companies, even here in northern California, that specialize in solar hot water, in contrast to the case with solar PV electric installers which are really common. Most companies that do solar hot water include it as a sideline in addition to their mainstream solar PV business. The consequence of this is that there are few companies that have a lot of experience in installing solar hot water. As in any field, more experience leads to a more reliable outcome. The reason very few companies specialize in solar hot water is that very few people want it, and also, it is more difficult to install because it involves plumbing and tank installation. The amount of site specific customization that needs to be done for solar hot water is therefore much more than for solar PV, which leads to more costs and more possibility for errors.

After checking out another company that does solar hot water installations as a sideline to their main solar PV business, we decided on Sunwater Solar in Richmond. Sunwater only does solar hot water systems and only indirect systems.

Another question was what kind of system to go with (direct or indirect, thermosyphon or ICS or drainback or indirect). A friend had a thermosyphon-like system, which uses a non-water based heat transfer fluid, installed a couple of years ago for around $7K, but it involved putting a 40 gallon tank up on the roof. I favored an indirect system over a  thermosyphon system to reduce the potential aesthetic problems (looks less like a science project) and because of the lower efficiency in a thermosyphon system, and over a direct system because of the potential for freeze problems in a direct system (temperatures here in coastal northern California were around 24F at night a few days ago, and that's also the temperature my collector was at). Some research on the Internet indicated that flat plate collectors perform better in our climate, due to the overheating problem in summer. For that, they take up more roof space but all in all, flat plate seemed like the way to go. So we decided to go for an indirect system with flat plate collectors.

We also needed to decide what we were going to do for solar water storage. The cheapest alternative would have been to use our existing gas hot water tank for solar storage and install a heat exchanger between the cold water inlet and the tank. Silicon Solar makes such a heat exchange. The problem with this kind of system is that it is much less efficient than if the heat exchanger were in the tank itself because heat is lost to the air. In addition, the tank we have is 40 gallons which means we would be able to store less hot water for cloudy days. So that suggested instead installing a second tank for solar hot water storage.

I researched storage tanks a bit and found out that there are basically three types: glass (actually ceramic) lined, steel, and stainless steel. Glass lined tanks are much the same as the cheap electric and gas hot water tanks that one can find at Home Depot and elsewhere, and that most homes in the US have. Both glass lined tanks and steel tanks require a magnesium anode to prevent corrosion. A little known (at least, I didn't know it) fact about the cheap electric and gas hot water tanks is that they, too, need a magnesium anode. Over time, the anode dissolves until, after 5-10 years (depending on the ionic content of your water), the anode disappears. When it disappears, it needs to be replaced, something most homeowners probably never do. If it isn't replaced, the tank corrodes and starts leaking. The upshot of this was that I decided to go with a stainless steel tank, to reduce maintenance. Unfortunately, this added substantially to the cost of the system.

The final decision we needed to make about our system architecture was what we would use for backup. In the short term, it seemed to make sense to use our existing 40 gallon gas-fired hot water tank as backup, since it had originally been installed around 2001 and was therefore relatively new. In addition, I had vague plans to do some deeper energy remodeling in the future, and wanted to put off the ultimate decision about what to do for backup until then. I briefly considered getting a solar tank with an integrated gas heater, but rejected that because the cost was higher, and because I was hoping at some point to reduce our gas usage to a minimum. So we decided to keep the gas fired tank for now and use the solar tank as a preheater, at least in winter. In summer, we could turn off the gas tank (it has a pilot light, very wasteful) because there is enough sun and the tank gets hot enough to last for several days without sun, though we rarely get many cloudy days in summer.

Solar Hot Water Part I - Fundamentals

So this blog begins a series of posts about solar hot water systems. Solar hot water is one of my favorite alternative energy systems because it is (theoretically at least) relatively inexpensive and it seems quite natural - put water out in the hot sun and let it heat up. Yet, very few people have installed solar hot water, even though such systems were quite common in California prior to WWII. In this series, I will go through the basics of solar hot water systems and describe the system we had installed this summer. I'll also talk about financials and some of the pitfalls involved in our installation experience.

This first post is about the basics of solar hot water systems.

In principle, nothing could be simpler. Unlike solar PV systems for generating electricity, solar hot water systems don't depend on any fancy quantum physics, they just depend on good plumbing. The idea is to put something on your roof (or somewhere else that gets a lot of sun) which traps heat from the sun, converting light into heat by absorption on a black surface, then transfers that heat to a fluid. That fluid forms hot water for domestic use. Solar hot water heating can also be used for space heating in winter, by running the hot water through hydronic heating loop pipes embedded in the floor.

There are two basic kinds of solar hot water systems: direct and indirect. In direct systems, the fluid heated in the thing on the roof, the collector, is the actual water that you will use for your domestic hot water. In indirect systems, the fluid is typically propylene glycol, a nontoxic fluid that is the basic component of antifreeze in automobiles (antifreeze also has toxic components too for rust inhibition and other purposes but those are not in the fluid used for solar hot water systems). Propylene glycol is used because the range of temperatures over which it remains fluid is much higher than for water. For example, a 60%  propylene  glycol/water solution freezes at -55F rather than 32F. Also, the same solution of propylene glycol/water doesn't boil until around 225F instead of 212F. This means that the pipes and collector are protected both  against freezing temperatures at night in winter and boiling hot summer days when your hot water tank already has enough heat and the system shuts itself off. The water or propylene glycol  in the pipe loop between the collector and your hot water tank is called the heat transfer fluid because it transfers the heat from the hot collector to the water in the tank (either directly if water or indirectly - through a heat exchanger coil in the tank - if propylene glycol).

The cheapest way to obtain a direct solar hot water system is to build it and install it yourself. Take a used gas or electric hot water heater tank, paint it black, put it into a box with a glass top, and plumb it into the domestic hot water loop in your house. Another variation is a do-it-yourself collector made out of a glass box and copper tubing painted black with the hot water from the collector running down from the roof through a box set in the ground filled with rocks.  The rocks act to collect heat while the sun is shining, and radiate heat into the water loop when it's not. There are many sites on the Internet where you can find plans for systems you can build for under $1000. These systems are not very efficient but they certainly are cheap. I'll not recommend any here, because I've not tried them, but if you are handy with tools, don't have a lot of money, and don't particularly care about performance, you might want to give it a try.

If you have more money to spend, there are three kinds of commercially available direct systems - thermosyphon systems, integrated collector storage systems, and drain back or drain down systems. Thermosyphon systems have no active pumping or other means of forcing the water to circulate between the collector and the hot water tank. Instead, thermosyphon systems depend on the tendency of hot water to rise off the collector. They have a tank attached to the collector usually around 40 gallons where the hot water collects. You can see the tank at the top of the collector in the picture below:

Cold water enters the collector at the bottom and rises up as it is heated. The hot water is collected in the tank at the top of the collector and from there goes  to the domestic hot water system, usually into the backup heater tank.

Integrated collector storage (ICS) systems are similar to thermosyphon systems in that they have some water storage in the pipes making up the collector. Unlike thermosyphon systems, however, the water pressure from the city main or well drives hot water into an auxiliary storage tank in the house.

Drain back or drain down systems also use the main water pressure to push water through the collector, but they use a different sort of freeze protection. Thermosyphon and ICS systems have a temperature sensor on the collector. When the temperature reaches the freezing point, the sensor causes hot water to be circulated into the collector to prevent freezing. This decreased the efficiency because in winter the hot water may come from the backup electric or gas hot water heater. In drain back or drain down systems,  when the temperature nears the freezing point a valve on the main side  of the collector closes. A valve on the house side closes too and a valve emptying the system opens. All the water in the collector and collector loop plumbing drains out. When the temperature rises sufficiently above freezing, the drain valve closes and the main and house valves open and the loop repressurizes.

The most expensive type of system is the indirect system. Indirect systems don't need to have freeze protection since the heat transfer fluid won't freeze in winter. An electrically driven pump drives the heat transfer fluid between the hot collector and a heat exchanger coil in a water storage tank. The heat from the heat transfer fluid is absorbed by the water in the tank, and the water then is used for the domestic hot water supply. When the temperature of the collector drops below the temperature of the tank, the pump shuts off. Similarly, if the temperature in the tank reaches a maximum (usually no more than 180F) the pump shuts off and the collector stagnates. At stagnation, the collector can reach very high temperatures, usually near the boiling point of water. Indirect systems need to have some kind of protection against stagnation, otherwise the heat transfer fluid can cook and become acidic. If that happens, the fluid must be replaced.

There are two kinds of collectors available for indirect and drainback systems: flat plate and evacuated tube. Flat plate collectors look like big flat glass skylights, except they are black. Here's a picture:

 

The simplest flat plate collector is just a piece of glass on top of a metal manifold or metal tubing coil through which the heat transfer fluid circulates. The manifold or tubing is painted black. Usually, insulation separates the manifold from the back of the collector to prevent heat from being transferred onto the roof.

 An evacuated tube collector consists of a collection of glass tubes from which all the air has been removed. Here's a picture:

The collector tubes extend vertically along the roof between a manifold on the top of the collector through which the heat transfer fluid circulates. A black heat pipe extends through the middle of the tube and contains another heat transfer fluid sealed in the heat pipe. When the sunlight strikes the collector, it heats up the heat pipe causing the fluid to rise to the manifold. Heat doesn't escape from the collector because there is no air inside to transfer heat, just as in a vacuum bottle. The heat exchanger fluid running through the manifold absorbs the heat from the heat pipe and transfers it into the hot water tank in the house.

Evacuated tube collectors put out more heat during the winter than flat plate collectors, and consequently are better for hydronic space heating systems, which circulate water through pipes in the floor. On the other hand, evacuated tube collectors tend to become too hot in the summer. Ironically, one of the major problems with solar heating systems is that they tend to get too hot in the summer. For domestic hot water systems, this isn't such a problem because you can size the system for maximum summer temperatures and limit the number of times the system stagnates. For solar space heating systems, however, you need somewhere to dump the heat, like a hot tub or swimming pool. In moderate climates, such as here in coastal California, flat plate collectors perform better overall because winter temperatures usually aren't that cold for extended periods.

Generally speaking, direct systems are not recommended in areas where there is any tendency to freeze during the winter. This includes areas such as coastal California, since we do get freezing temperatures at night. The thermosyphon and ICS systems are less vulnerable to freezing because they keep more hot water in the collector or near it where it can be recirculated to inhibit freezing, but in a really hard freeze there may not be enough water to recirculate. The drainback systems can freeze if the power goes out. If the direct system is only used during summer and completely drained in autumn before the first freeze, they won't freeze, but in general, an indirect system is better if freezing temperatures occur.

Solar hot water systems require some kind of backup gas or electric water heating for when the sun doesn't shine and in winter when there may not be enough sun to fufill hot water needs. One common way to install such systems is to make the solar hot water system a preheater that heats water prior to entering the backup heater tank. Another way is to build an electric or gas heater into the solar hot water storage tank, or have a separate heat exchanger coil in the solar hot water storage tank through which a heat exchanger fluid from an external boiler, like a gas boiler or a geothermal heat pump, can be circulated. A final way that doesn't seem to be very common but seems sensible is to have an on-demand electric or gas heater provide additional heat to the solar heated water if it is not hot enough.

China, the US, and the Problem

China and the US have announced their opening positions for the Copenhagen talks. Expectations were set low a couple weeks ago in Singapore, and the two biggest carbon polluters predictably came in even lower:

• Obama promised to reduce overall US carbon emissions by 17% by 2020. Not coincidentally, this is precisely the amount cited in the Waxman-Markey bill passed by the US House of Representatives as a goal for that date.
• China promised to try to increase the carbon efficiency of its economy, i.e. reducing the amount of carbon emitted per unit of GDP, by somewhere between 35-40%. This would still result in a net increase in carbon emissions, since the Chinese economy is growing so fast.

Needless to say, these kinds of half measures and vague promises aren't going to solve the problem. If they had been made 20 years ago, they would have been a start, but it is too late now. Come to think of it, they were made 20 years ago, that's what the Kyoto protocol was all about.

What do we need to do to start solving the problem? In the US, how about 30% reductions by 2020 and incentives and regulations to enforce it? That's what California is planning (California, incidentally, is the 8th largest economy in the world). For China, how about a policy decision (not a vague promise) to henceforth make all development sustainable, and involve renewable or non carbon polluting energy?

Yes, I know China still has a large population of rural poor and it's really tough that they ended up developing now when the atmosphere has no reserve left to take on carbon. But physics doesn't really care about the Chinese national ego. If they end up putting that carbon in the atmosphere, they are going to end up cooking and cooking us in the process. They don't have to run their economic development like we did, they could take a different path. They need to return to the spirit of Mao, who did try a different path (unfortunately, he really didn't know what he was doing and wasn't willing to accept any criticism) but this time with something that will work. If they do that - make their economy essentially free of dependence on fossil fuels - they will essentially end up with an economy that is far in advance of the US. In a sense, China has a much easier job than the US, because they could start out with a carbon-free economy instead of having to convert an already existing one.

What should the US do? Well, instead of pork-barrel cap and trade, which has largely been given away to every industry crying about how hard it will be to meet the caps, how about a carbon-added tax? This works like a value-added tax, except it taxes the amount of carbon involved in the steps of producing and delivering a good or service. Measuring embedded carbon is difficult, but phasing the tax in over time to allow measurement procedures to be worked out could reduce the amount of difficulty. The carbon-added tax would be applied to everything that is produced in the US or imported. This last point is important, because it takes away an argument China has against the provision in the Waxman-Markey bill to tax imports from countries that are lax about carbon reduction. China can easily take this to the World Trade Organization and get a ruling against it as an illegal restraint of trade. If, however, the tax applies to all goods both domestically produced and imported, then they would have much harder time arguing that the tax is directed at restricting imports. Cap and trade, in contrast, is an invitation to political manipulation, and that is exactly what happened in Europe, where it was instituted, and in the US House, where most of the credits were given away during negotiation of the Waxman-Markey bill. It will have almost no impact on carbon  emissions until after 2020.

If this is the best Obama can do, then it sure isn't "change we can believe in". It's more like "change to keep the coal magnates and right-wingers comfortable and ensure that polar bears perish". Arnold Schwarzenegger, California's ostensibly Republican governor, is doing much better, he's fully behind the 30% reduction.

Show Me the Money!

Before I get started talking about how much the 55% carbon emissions reductions I reported on here cost, I'd like to spend a little time discussing the conventional thinking about the cost of carbon reduction. Most writing about this on the Internet talks about "payback time", in other words, how long it will take for you to earn back the amount of money you invested in the renewable energy system, efficiency improvement, etc. The idea behind this thinking is that because these improvements result in a net reduction in fossil fuel costs, the purchaser of the carbon reduction product should expect some kind of financial gain on the transaction, at least, as measured over time.

I believe this kind of thinking is faulty. To see the problem with this thinking, suppose there were available a carbon reduction  product that required ongoing periodic fuel charges,  but the fuel didn't generate any fossil carbon. A car that runs on 100% ethanol is an example,  or a solar hydrogen generating system for home heating. The product may or may not be more expensive than a similar product that generates fossil carbon (ethanol generates carbon but it is recycled), and the fuel may or may not be more expensive than a fossil carbon based fuel. Nobody would ask about the "payback time" when buying one of these products. Of course,  people might make purchasing decisions based on the product cost itself and the cost of ongoing fueling. Some folks may even choose to buy the renewable product even if it is more expensive than a fossil fuel based product, or if the fuel is more expensive, just because they want to help contribute to carbon reduction.

Furthermore, consider a consumer trying to decide whether to buy a consumer electronic good or a renewable energy technology device. Nobody asks "what's the payback time on a plasma TV?". Or "what's the payback  time on a Lexus?". I suppose if you rented the TV out to your neighbors or showed movies on Saturday night and charged admission, or used the Lexus as a taxi  you could answer the question, but people don't even expect any payback time for these kinds of goods. There is a net financial loss when you buy them, what you get from these is  the utility derived from using them,  which you otherwise wouldn't have (well, OK,  there are also the intangible benefits of looking like a cool guy who Made It when  you drive the Lexus).

The point I'm trying to make here is that "payback time" isn't a useful primary criterion when talking about the cost of consumer-financed carbon reduction products. Environmentalists and some economists have sold the public on the idea that they'll save money over time if they buy these products as a way to counter the fact that the products themselves are generally more expensive than the equivalent fossil fuel-based products. But while that's a nice extra, the real reason for buying carbon reduction products is that if we don't start urgently deploying them now, the planet is simply going to cook. Weighting a devastated Planet Earth, in which the mid-latitudes have become desert and agriculture no longer works, against the extra cost of the renewable device certainly indicates where my buying decision would come down. Now, this doesn't mean that economic factors shouldn't be taken into account, it just means that the primary criterion for a consumer buying a carbon reduction product should in my mind be: which product can I afford that pulls the most carbon out of my lifestyle the fastest?

So my favorite figure of merit for measuring the economic effectiveness of carbon reduction products is the "one year cost per unit weight carbon eliminated". That is, the cost of the product divided by the unit weight of carbon eliminated as measured year over year from before the device was installed until after. Some folks like to talk about the "lifecycle carbon reduction v.s. cost"  but I feel that the problem is so urgent that products which result in more carbon reduction now are preferred (kind of like the time value of money, a dollar now is worth more than one in the future). The "unit weight" I use is the kilogram (kg), since carbon emissions are typically measured in metric tons (mt) (1000 kg = 1 mt).

The graph above shows the unit cost per kg of one year carbon reduction for the various treatments we've applied to our house and car. The costs for renewable energy technologies (solar PV and solar hot water) reflect rebates and tax reductions. The two hybrid car costs ( Model I and Model II Prius) reflect a hybrid premium (around $3500) above the equivalent fossil fuel powered car (a Corolla in this case). In other words, we could have bought a Corolla, we chose a Prius and payed a little extra. Finally, some of the costs reflect aggregate treatments. For example, in the solar PV case, we not only installed solar PV,  we also removed two huge pool pumps and the pool they went with, plus bought an energy efficient washer and dryer and CFLs, so I can't break out the contributions of each individual product. Similarily with the plug-in hybrid, the cost consists of both the hybrid premium and the cost of buying and installing the aftermarket battery pack.

Notice something peculiar? Most commentators (for example, here) claim that efficiency improvements are far more cost effective than renewable energy technologies in reducing carbon. There is even a well known study from McKinsey and Associates (not free unfortunately) backing up this claim. Yet, my direct experience here is exactly the opposite. The two efficiency treatments (double pane windows and a new refrigerator)  had a per kg carbon reduction cost almost 5x the renewable energy technologies. The most cost effective reduction products were the hybrid cars.

This is quite puzzling. My speculation is that for a reasonably well insulated house, such as ours, with reasonably energy efficient appliances, the reductions obtained from "low hanging fruit" type efficiency improvements are simply not available. Some of the studies on the advantages of energy efficiency assume a house with no insulation at all, leaky hot air ducts, and a refrigerator from the 1950's. Our house isn't in that category.

The other possibility has to do with where the money goes for renewable energy technologies v.s. efficiency improvements. As anybody who has done home remodelling knows,  labor makes up half to three quarters of the cost, depending on the job. The high labor costs in northern California mean that anything involving remodelling is likely to be costly regardless of how cheap the materials are. In contrast, the renewable  energy  technology products generally take very little time to install (it required around 4-5 hours to  install the booster battery in my Model II Prius) or can even be used out of the box. There are exceptions - solar hot water for example requires lots of labor to put in and must be custom designed for the site.

A real eye opener is comparing these costs to the cost of carbon offsets. PG&E offers billing for carbon offsets as part of our monthly energy bill. They charge around $0.012 per kg carbon (based on the cost of offsets for fossil gas), almost three orders of magnitude less than the cost of solar hot water system.

My conclusions from this study are:

1.  If you can't afford anything else, sign up for carbon offsets with your utility if they have them, or go to a Web site like Carbonfund.org (a nonprofit) and buy carbon offsets.
   
2. You get the most carbon reduction  for your dollar by buying a hybrid car that gets substantial reductions (not a hybrid Lexus) like the Prius
3. Solar hot water or a pluggable conversion for a Prius come next.
4. PV and reduction in large electricity hogs like pool motors are next.
5. Unless you have a really poorly insulated house or are committed to making your lifestyle net zero carbon, efficiency improvements like new double pane windows and insulation are last (of course there are other reasons why you might want to do these improvements).
   

Foam Catastrophe

This summer, we decided it was about time to investigate some leaks we had in the roof. Water stains showed up on the front bedroom closet wall again, after I rinsed down the solar panels thoroughly, in a place where we had them three years ago. I thought we had the leak fixed, but it was just the drought, there hasn't been enough rain to really show up. So we had the drywall taken out on the front and back bedroom closet. The back bedroom closet was smelling of mold, as was the front, though there were no visible leak stains.

After finding and fixing the leaks, and having the mold treated, we were left with two open ceilings. Previously, they had been packed with fiberclass insulation, but I had some closed cell foam left over from the solar hot water closet installation, so yesterday I decided to try foaming the back closet ceiling. Since the temperature at night has been below the recommended temperature, I put on an electric heater for four hours in the morning to heat up the closet. After it seemed warmed up enough, I donned the foamer's Tyvak suit and went to work. Here's me in the suit.

 If you've ever done foaming, you know that these suits are absolutely essential because the foam goes literally everywhere and especially where you'd rather not have it, like in your hair and clinging to the hair on your arms.

I had two sets of tanks (2 tanks per set, one with the resin and one with the setting agent). I took the first tank and foamed up about three quarters of the ceiling before it started to run out of pressure. When pressurized foam dispensers run out of pressure, it's hard to get them to the target without actually being up against it, not possible on a high ceiling. In addition, the foam started peeling off the ceiling at the high side, possibly because the ceiling didn't get heated enough by the electric heater.

In any case, I shut down the first tank set and started up the second. This set was nearer the heater. Right away, I knew something was wrong. Instead of expanding out into billows of foam, the mix came out as a blue fluid that didn't blow out much. I tried it a while, thinking that maybe it was a startup transient, but the fluid started dripping down on the ladder and the tarp covering the floor. So I shut down the tanks. Here's what the tanks looked like after the ceiling had about stopped dripping;

You can see the blue fluid (kind of like the water in a toilet that has one of those sanitizers in it) dripping off the shelf. I think the problem was that the tanks were too warm. These foam systems have a relatively small temperature range over which they will set.

At any rate, there were small pools of fluid on the floor and the ladder was dripping with it. Trying to figure out what to do, I read the instructions and it suggested sopping up spills with sawdust. Seeing as I didn't have any, I decided to try kitty litter (works for oil spills for example). I went to the hardware store and got a box of kitty litter, a plastic trowel, and a couple of large plastic containers in which to put the refuse.

The kitty litter worked fine, sopped up the fluid, and I used newspapers to wipe down the ladder. Then I took the ladder outside on the driveway, washed it down with a mixture of ammonia and detergent (as recommended in the directions), and hosed it off. The chemicals in the foam are water soluable and nontoxic, so there was no problem with washing it outside. I disposed of the tanks in the plastic containers along with the kitty litter and the rest, but left the tarp on the floor to catch any remaining drips. Today, it looks as if it is done dripping.

The result was not what I had expected, but about three quarters of the ceiling is foamed up. Here's a picture:

The bluish color at the upper end of the rafter bay is where the second tank failed to foam.

I think I'll probably talk to a professional about finishing the ceiling. Closed cell foam is the best insulation available (R-6 per inch, 2x the R-3 of fiberglass batting and much better for moisture and air sealing) but it is a difficult material to work with which is probably why these larger two component systems aren't available through Home Depot. I've done a couple of major foam projects now, and I use it a lot for small touch ups, like around electrical outlets. I think there is a lot the manufacturers could do to make the dispensers easier to use and less likely to waste foam by spraying it everywhere, but I'll probably keep using foam (though not for a large job I do myself) since it is convenient and the best insulation for the price.

Outline of A Solution

Is it possible to take a slightly atypical boomer couple (we don't have any kids) living a typical suburban lifestyle in a typical California suburban house and achieve radical carbon reduction in a short amount of time? I set out to answer this question in the affirmative when we bought our 1976-vintage, 2800 sq. ft. single family in 2003. Prior to that, we lived in a 1500 sq. ft. townhouse that shared a wall with another unit, vintage 1979. Achieving carbon reductions there was relatively easy. Would it be possible (if not easy) with a large suburban single family? And could we do it without having to fall back into an overly ascetic lifestyle, and within an amount of time that would have some hope of bending the global carbon curve downward enough in the next ten years (if everybody could do it), so that the planet doesn't fry?

The graph above shows our progress so far. It contains the annual carbon emissions measured in metric tons CO2 for each of three categories of suburban living: electricity, natural gas (space and hot water heating, cooking) and two cars, from 2002 to 2009, 7 years. Before going into details, a few words about how the graph was generated. Since we are obviously not yet at the end of 2009, the figure for 2009 is an estimate based on usage so far. Likewise, the figures for 2002 and 2003 are estimates. We bought the house in fall 2003, and the estimates of gas and electricity usage are based on 9 months of data for 2002 and 2003 given to me by the previous owners, and the last month in 2003 from our own usage, before we introduced any energy saving measures. Other than that, the gas and electricty figures from 2004 through 2009 are as accurate as PG&E can get it to me.

Likewise, the figure for the car in 2002 and 2003 is based on our cars and not that of the previous owners, so the numbers for those years are a composite. They are what we would have used had we lived in the house with our cars. The car figures are based on the approximate measured miles per gallon of the cars we owned,  a milage of around 10,000 miles per year on the higher mpg car and 8,000 miles per year on the lower mpg car. Again, this is an estimate but one I've found to be fairly accurate for our family.

As the figure shows, we've managed to reduce our carbon footprint from over 12 metric tons to just under 6 metric tons in 7 years! That amounts to a 55% reduction. The graph below shows our year by year percent reduction.

Our experience shows why talk of postponing radical carbon reductions until after 2030 is such nonsense. The Waxman-Markey bill proposes a mere 17% reduction in 10 years, by 2020. Even people involved in green remodeling have proposed a 25% reduction in 20 years for residential buildings, and that based on buildings from the 1950's where the building codes for insulation were nowhere near what they were even in the 1970's when our house was built. These are timid, half hearted proposals that are not going to solve the climate problem. We need massive reductions, and we need them soon.

A few high level observations about our experience (but details to come in future posts):

• Renewable energy and alternate energy cars are a vital and important part of the mix. They get reductions on the order of 20, 30, up to 100%. The massive reduction in our electric emissions between 2003 and 2004 was due to installing a solar PV system, and we are currently undergoing a similar but smaller reduction in gas usage due to a solar hot water system installed this year.
• But changes in lifestyle and operation are also quite important too. For example, we originally sized our PV system to replace 2/3 of our electric bill. Then in 2004 we took out a pool and put in an energy efficient electrically heated hot tub. The pool had two large electric pumps which went on minimum once a week. We keep the hot tub at 80 degrees until just before we use it,  it's on 220V so it heats up in about an hour. The solar PV system subsequently covered around 115% of our electric use, so we now have some spare capacity. Likewise, setting the thermostat to 68 degrees in the winter and turning off the furnace pilot light in summer reduced the gas bill by about half between 2003 and 2004.
  
• Electrical efficiency improvements like Energy Star appliances, CFLs, etc. seem to help but heating efficiency improvements like double pane windows don't. We had double pane windows installed in 2004 and saw no difference in our gas bill, though the house is less drafty and quieter. On the other hand, the electrical efficiency improvements we installed in 2004 resulted in a modest additional drop in our electrical usage, which added to our PV surplus.
  
• Natural gas emissions seem to be more difficult to reduce than others. Auto emissions can be reduced by simply not driving as much. And PV is a really simple way to reduce emissions from electricity. But there doesn't seem to be a renewable energy technology for the uses to which natural gas is put that is as easy to install in an existing home and as cost effective as PV.
  

Now, this carbon footprint doesn't include airline travel. Anybody who has done a carbon calculation knows that airline travel dwarfs any other source of carbon. More on this in later posts. It also doesn't include embedded carbon, such as from food, products we buy, etc. Getting an accurate measurement on these sources of carbon is difficult, to say the least. Maybe that might be a theme for another post too. And I've not said anything about costs, I'll talk about this in future posts too (though one of the themes of this blog is that people make too much of the costs of carbon reduction, the cost of the planet frying is certain to overwhelm that but nobody cares to put a number on it in comparison).

We are clearly on the way to 80% and maybe even to net zero!

The Scope of the Problem

So today is Blog Action Day and the topic is Climate Change. Since that is mostly what this blog is about,  I signed up to write something.

What I want to talk about is the scope of the climate change problem. My feeling is that much of the discussion in the media about climate change is really quite superficial and underestimates the depth of the commitment we are going to have to make as a civilization in order to solve it. The noise made by "climate change deniers" is quite evident and also, in the face of the scientific evidence, quite ludicrous. Most people realize that by now. But there is a more serious problem with the bulk of the population. I think most people truly believe there is a problem but they don't rate solving it as very important, or maybe they believe that the solution requires minor changes, like putting in a couple CFLs as in my last post (not to say that CFLs aren't part of the solution, but they aren't the full solution). Tom Friedman, in his book Hot, Flat and Crowded, discusses this problem in some amount of detail. It is easy to see reasons why this might be the case: general media laziness that seems to have crept in over the last 20 years, a desire not to alarm people by disclosing the depth of the problem, perhaps a lack of understanding of the underlying science.

To illustrate the scope of the problem, consider the graph above. This graph shows the yearly increase in CO2 concentration measured at the top of Mauna Loa from the start of measurements in 1959 until 2008. The first thing to note is that the yearly increase, itself, is increasing, especially since around 1998-2000. Now, we all know that the base level of CO2 in the atmosphere is increasing, but what this graph is saying is that the *rate* at which the CO2 concentration is increasing is, itself, increasing. So it's like a car which is accelerating, going faster and faster. The problem would be bad enough if the level of CO2 was increasing with the rate of increase being constant, but the fact that the rate of increase is increasing means that we are likely headed for serious changes in the climate much sooner than most people expect. Most media reports on climate change don't talk about this problem.

The next thing to note are the blue rectangles. These rectangles are the approximate locations of economic recessions. In every case, an economic recession is accompanied by a decrease in the rate of CO2 increase. Sometimes the effect lasts for a couple years after the recession is officially over. As we all know from the recession of 2001-2002 and the current recession, the date that a recession is declared "officially" over often precedes by a considerable amount of time the date when people actually feel economically well off enough to declare that it is psychologically over. This effect does seem to have been picked up by the media, I've seen estimates that U.S. CO2 emissions have decreased by around 6%  year over year since 2008. The reverse correlation - i.e. that decreases only occur with recessions - can't be maintained though. There are decreases in 1964, 1996, and 1999 that don't correspond to recessions.

These two observations, in a nutshell, describe how serious the problem has become. The increase since 2000 is most likely due to India and China. These countries are building coal fired power plants, their people are buying cheap cars, and they are, generally, behaving like Americans did in the 1950's, Europeans in the 1960's, and Japanese in the 1970's - becoming more and more prosperous and thereby generating more and more carbon emissions as a byproduct. Unlike other pollutants, CO2 is an inescapable byproduct of prosperity (hence the decrease noted during recessions). At least, that is so given our current economic system - which needs growth for people to feel happy and well  off - and our currently affordable energy generation technology - which is based on fossil fuels.

The Indians and the Chinese rightly complain that it is our fault that the atmospheric capacity is used up, and why should they suffer because we hogged all the goodies? In a sense, they are right. And I would not put it past the Chinese to become the first industrialized society that bends their carbon emissions curve downward. With their authoritarian government, all it would take is a serious commitment, and, lately, they seem to be getting serious about carbon reduction. In the Western democracies and India, however, the evidence has been a sad lack of ability to act. The most environmentally aware societies on the planet are in Europe, and the Europeans have been consistently unable to bend their carbon emissions curve downward while maintaining economic growth,despite the appearance of political will since 1990. Their attempt at cap and trade ended up in political horse trading. Something similar is happening in the US. The Waxman-Markey bill is a joke, neutered by coal-state representatives. Most of the carbon credits are given away free to polluting industries and the emissions goal for 2020 is ridiculous. The Senate bill - should it ever happen - will probably be even worse. And the prospects for any kind of treaty in Copenhagen in December are slim (not to say that the US Senate would ever ratify one). Today I even read that the Saudi Arabians are brazenly demanding that they be compensated if the world's oil usage goes down!

These goings-on are what one would expect and what typically happens when people try to solve a problem: jocking for advantage, trying to blame the problem on someone else, trying to avoid having to do anything oneself, etc. It's just politics. The problem is, this is not a problem that can be solved by the usual political horse trading, we simply can't bull***t this problem anymore. We have run out of time. It is a basic scientific fact that the more carbon and other greenhouse gases we dump in the atmosphere, the more likely there will be serious changes in the climate. And if we dump in greenhouse gases faster and faster, the day of reckoning will come even sooner. Today, I saw a report that the Arctic is likely to be ice-free in 10 years. When the IPCCC did their first report, they estimated it would be 2100 before that happened.

The fact that I'm so pessimistic about solving the problem on a political level is one reason I'm writing this blog. What it will take - and I really want to be clear about this - is a fundamental change in what people value. I think we need to start in the US, Europe, and Japan, because the bulk of people in China and India are still quite poor and we cannot expect them to bear the brunt of solving this problem (though I do believe they can benefit from our efforts and will). The kinds of changes in lifestyle I will be talking about later in the blog, like renewable energy technology, are not cheap, but I believe the US, Europe, and Japan are prosperous enough that we can really afford them. Somehow (and I don't underestimate the difficulty of this), people need to value carbon reductions and other environmental measures enough that they would rather take out a HELOC on their house for a solar thermal hot water heater than  for a trip to Maui or a plasma TV. Maybe that's expecting too much, and of course the government needs to help with incentives, but I don't think we can solve a problem of the scope of climate change in any other way.

On Lighbulbs

The New York Times says that CFL purchases have been falling off. People don't like the color, the price, that the bulbs contain mercury, that they often can't be dimmed, that they take a while to come up to full brightness....

Well. I've been using Compact Fluorescent Lamps (CFLs) since the early 1990's, and I have a bit of trouble understanding what all the fuss is about. When I first started buying them, they were around $12-$15 apiece. I put them in all the major lights in our house that were on often. Lights in closets and such that rarely were on stayed as incandescents. In the late '90's, I had a guy come in and look at my electric consumption to install solar. He told me our house was one of the lowest consumption houses he had seen, and that it didn't make sense for us to get solar (we did a bunch of other stuff to save electricity too). The CFLs I bought around 1994-1995 lasted until we moved into the new house in 2003. I don't recall ever having replaced any. I did replace some of the CFLs I bought in 2003 last year though, since they were getting dimmer.

Nowadays, CFLs run about $1.50, and most of the problems people seem all worked up about are solved. The light quality is definitely different than incandescents, but it is quite acceptable. The picture below, from Wikipedia, shows a group of 4 bulbs. The second from the left is an incandescent bulb, the rest are all CFLs. The only CFL that looks "cold" is the one on the far left. That's a 6000 Kelvin bulb. The other two on the right are around 3000 Kelvins and are indistingushible from the incandescent to my eyes.

Most CFLs these days come up to full luminosity within around a minute, some even right away. As for dimming, well, do you really need to dim all the lights in your house? Use incandescents in the bedroom or dining room if you must. My chandelier has incandescents, as do the hall lights, but they are low wattage (around 20 watts) and we  rarely use them anyway.

The mercury is a problem, but it is manageable. I put my used CFLs into a box for toxic waste disposal. We did have a CFL break, but it was cleaned up and the room aired out. It broke on a tile floor so there was no problem with the mercury being absorbed into a carpet. Fortunately, because CFLs wear out so infrequently, they rarely are thrown away. All that said, I think the manufacturers and local municpalities could do more, for example, have recycling bags specifically for CFLs like they do in my town for batteries. And fluorescent tube lights have been in use for years without mercury being a problem.

So what about LED lights? The blogs and green news sites are all aflutter with reports about how LEDs are going to replace CFLs.

I had looked at LEDs a couple years ago when we remodeled our kitchen, but had decided in favor of fluorescents (tube model) because the amount of energy savings was not up to what fluroescents provide, and the cost was about 40x as much. A couple weeks ago, I saw a news item about a new LED light, the Pharox from Lemis Lighting. They were offering a 60 watt bulb replacement for $40. Admittedly, this is still 26x the price of a CFL, but I consider myself an early adopter, and one of the tasks of an early adopter is to try new things out despite the price (as long as it isn't too exorbitant). So I ponied up $90-odd (including tax and shipping) and got back two bulbs. Here's a Lemis bulb in front of it's widget-like packaging (which I think is supposed to make you feel good about the price):

What a disappointment. The light was much too dim for reading in the living room. I had to put them into a nightstand table in the bedroom and in our hall bathroom. These are areas where we don't have the lights on much and fine details (like 10 point type) are not important. If I had to rate the wattage, I'd say it was more like 40 watts. Of course, these LED lamps could be dimmed, but so could CFLs at 1/20 the price.

In the New York Times Green, Inc. blog article, Lemis conceded that the light output might not be equivalent to 60 watts after all. They gave a typical, weasel-worded marketing explanation that "it depends on how the bulb is used" (sure, and if I put a mirror behind it, it will look like a 100 watt bulb). Their ostensible 60 watt bulb puts out 336 lumens, a 60 watt-equivalent CFL puts out 800 lumens. A 40 watt incandescent puts out 400 lumens, so the Pharonx is actually about equivalent to 40 watt bulb. Not only that, but if you look at the energy efficiency, it's around 60 lumens per watt. That is exactly the energy efficiency of the CFLs that you can get today, at 1/20th the price!

So I guess LED lighting has made some progress in the last couple years. Now the efficiency in terms of lumens per watt is about the same as CFLs instead of less. The price is still way out of line. The lifetime of the LEDs is much longer, something like 20 years, but if CFLs last 5 years, as mine have, then I would buy only 4 in that time and still save over the cost of an LED light. Plus the fact that the light output from the LEDs is too low for reading. I wonder how much a decent LED for reading would cost, probably over $100.

Anyway, I guess I'll just stick with CFLs for now,  and deal with the mercury by recycling my bulbs back to the toxic waste pickup.

Buying Cars

So the other week I had a conversation with a colleague at work about why people buy hybrid cars. He maintained that people mostly bought hybrid cars because they expected to save money on gasoline, but given the price premium for hybrids and with the price of gas at around $3.00 per gallon (what it is currently in the Bay Area), they would be sadly disappointed.

Most studies of consumer behavior show that, paradoxically, the more expensive the purchase, the less likely a person is to rationally do a cost/benefit analysis. If you are buying a mobile phone, for example, you'll likely go through a pretty thorough comparison of the feature set with the cost, even if only mentally. With houses and cars, on the other hand, people are more likely to go with their intuition. And, even more paradoxically, most people are happier with purchases that they approach intuitively, or maybe its just that they don't mind suffering buyer's  remorse over a $200 iTouch while for a $20,000 car it would be too much.

At any rate, I pointed out to him that most people bought hybrid cars largely for the same reasons that people bought any car, though of course saving on gas was definitely a factor. These are (in order of most important to least important):

1. Because the car's image fit the image they wanted to project to the world,
2. Because they liked the styling, technology, comfort, ride or some other physical characteristic of the car,
3. Because the car had a reputation for reliability and efficiency.

So people buy a Lexus because they want to advertise they've made it, it has a comfortable ride and the latest in automotive technology, and like all Toyota products, it has a reputation for reliability.

And people buy a Prius because they're concerned about saving the planet and want to show it to their friends and neighbors, the hybrid technology is the latest in drivetrain technology and the car has a nice ride (though of course not as cushy as the Lexus), and in addition to the standard Toyota reliability, it near the top of the charts for vehicle efficiency (some diesels are higher).


As another data point, consider that the only hybrid which has sold really well is the Prius, which is a brand specifically identified with hybrids. Toyota tried to turn their hybrid drivetrain technology into a brand ("Hybrid Synergy Drive") but the hybrid Highlander, Camrey, and Lexus which have the drivetrain brand haven't sold nearly as well as the Prius. Similarly with the hybrid Honda Civic (the Insight doesn't count, it was too small to really be competitive for most people). People buy a Prius because they identify with the brand and they want others to know it.

As an engineer, rationally, I find this a little puzzling but then I think about my own auto purchasing behavior. My Plug-in Prius (converted by adding an A123 Systems booster battery) has milage up to 110 mpg with all-city driving, cost about as much as a Lexus, and has a ride more like a BMW because they had to add special shocks to handle the extra battery weight.  It's also got a lot of decals on it identifying it as a plug-in hybrid electric vehicle (PHEV). I got the decals put on so that people would know that, despite all the delay (especially at Toyota), PHEV technology could be here today if the auto companies just put in a little effort. OK, so maybe I wanted to project a particular image to the world a little too. :-)