Wednesday, February 17, 2010

The Electric Car Resurrection I: Some Background

If 2003 was the year when GM killed the electric car, then 2010 is shaping up to be the year when it is resurrected. Nissan is currently firming up plans to sell the Leaf by year's end. GM is on track to release the Volt (not an all electric but close). Tesla has had their Roadster out for a couple years now, and recently I actually spotted one on 237 while driving to work in the morning. Then there are the smaller players, like the Fisker Karma, a plug-in hybrid like the Volt but more expensive, and the Chinese manufacturer BYD that is backed by Warren Buffet. Is the electric car now about to go mainstream and solve our problems with Mideast oil, carbon generation, and pollution?

After seeing the documentary film "Who Killed the Electric Car?" in 2006, I decided to look into what it would take to get an electric car. At that time,  there were exactly zero commercially available electric cars, not even at the $109,000 price of the Tesla. So the only alternative was to convert an existing ICE powered vehicle to electric. I spent about two years researching what that would take.

My first stop was Electroautomotive, a company in nearby Felton that has been doing conversions and offering conversion kits since the energy crisis of the '70's. I attended a one day workshop on conversions held by Electroautomotive in Silicon Valley. I found out that the technology for hobbist conversions basically had also changed little since the 1970's. They were recommending a 80 volt DC system with flooded lead acid batteries. My 2002 Prius has a 274 volt NiMH battery pack and AC traction system. The range for one of their conversions varied depending on the weight of the coverted vehicle. For maximum range, they were recommeding using a 10 year old Geo Metro, since the weight is under 1500 lbs, or a light weight pickup truck, also preferably 10 years old, and then filling the back with batteries. Cost would probably have run around $8K-$12K depending on batteries and components, and, of course, I would have had to do the conversion work myself, no small problem since I am by and large hopeless with tools more complicated than a screwdriver.

The problem with converting a 10 year old car to electric is ... you end up with a 10 year old car (dents, cracked plastic from aging, no airbags or antilock breaks, stained upholstery) that goes maybe 100 miles if you are lucky. I looked into converting a new car, but there were only three cars on the market that were at or under 1500 lbs - the Toyota Yaris, the Honda Fit, and the Chevy Aveo. These are tiny cars with very little room for batteries. Given the minimum amount of room, the range would probably have been less than 100 miles.

Then there are the batteries. Lead acid batteries only last around 3 years when used as traction batteries in electric cars. Even though they are cheap (maybe around $800 for a full set) and they are up to 99% recycled, they are still heavy and having to swap out the batteries every 3 years is a major inconvenience. Flooded batteries were recommended for automotive traction applications because they have the best power output, but they are notoriously fickle and require checking periodically to be sure the plates aren't drying out. Sealed batteries require less maintenance but they don't provide enough range.

While I might have been able to live with having an expensive 10 year old car, the range was the show stopper. I wanted at least 120 miles so I could comfortably drive up to San Francisco and back without recharging (not of course that I do such a drive often, but I at least wanted to be able to do it in principle). So the next thing I looked into was lithium batteries. In principle, I would have been able to get the range I wanted, but the cost would have been prohibitive, around $20,000 just for the batteries. At the time, there was only one company that was selling prismatic lithium ion batteries appropriately large enough for such applications, Thunder Sky in China. Lithium ion batteries require a different kind of charging system and are much more sensitive to overcharging and extreme draw down than lead acid batteries.

I then turned to the local Electric Autombile Association and attended one of their meetings to find out whether anyone had experience with lithium batteries. The meeting was interesting, the featured speaker described an electric motorcycle for racing in which he attempted to clinch the world land speed record for 2 wheeled vehicles (I think he succeeded in the interim). His strategy was to essentially draw down the lithium batteries so fast that they were essentially ruined after one run, then to swap them out for the next. Not a strategy that would work for my vehicle, however.

After asking around, I got some warnings about Thunder Sky batteries, that the quality was variable. Someone said they had bought a bunch and some had turned out to run down after only a few charge/discharge cycles. Left unsaid, however, was whether the battery chemistry was safe for vehicular applications. I don't know what chemistry Thunder Sky used, but the battery chemistry used for laptop and cell phone batteries is completely inappropriate for vehicular applications without lots of additional engineering. Tesla, for example, spent years designing an explosion control cabinet to contain any of the thousands of laptop battery cells they use in the Roadster from igniting the others should a cell catch on fire. If Thunder Sky used the same chemistry as used in laptop batteries, an electric car with those batteries would have been a dangerous hazard should an accident occur.

I also finally got real about my ability to do the conversion work. Realistically, even if I got a membership at Tech Shop, there was no way I would have the time nor the motiviation to pursue the project to completion. I asked around at the Electric Automobile Association whether anybody knew of a place that would do a conversion. There was a guy there who said he would do one, we took up an email correspondence but it turned up he was really interested in selling electric scooters and the correspondence was just talk. I searched the Internet a bit. The Internet search turned up one guy in LA who had been doing conversions, but he had since stopped. There were some conversions for sale in San Francisco, a Toyota Yaris if I recall correctly, but the range was under 100 miles.

In the spring of 2008, I was just about to give up in despair when A123 Systems announced their L5 modules for turning a 2004-2008 Prius into a plug-in hybrid. And that is the subject for another post.

Saturday, February 6, 2010

Recalculating Solar Hot Water Performance

My previous post on the carbon reduction cost performance of my solar hot water system was unduly pessimistic. I now have the December gas bill and it looks as if the reduction is about 10% for a half year of use, or an estimated 20% for a full year, which is what I had originally figured it would be. That considerably improves the carbon reduction cost performance. Here's what the new chart looks like:

As you can see, the per kg. carbon reduction cost for my high end system is really around $27 per kg rather than $67 as in the last post. For the low end thermosyphon system, the performance is even better, around $9 per kg.

Furthermore, the state of California recently announced a subsidy of up to $1500 for solar hot water systems, on top of the 30% federal tax rebate. The last two bars show the per kg carbon reduction cost for the low end thermosyphon system and my high end system taking into account the subsidy. The subsidy still doesn't make a solar hot water system competitive with a gas fired tank hot water heater, but it helps. Figuring that at gas fired tank system costs maybe $1500 installed, it would still take around 15 years of gas savings, assuming the price of gas stays constant, to make up for the difference between the $3300 subsidized, after tax rebate cost of the low end thermosyphon system. The high end system would take longer.

Of course, if you have an electric hot water heater, the savings could be considerably better, since electricity costs more per joule of energy delivered to the water.

Thursday, February 4, 2010

Update on Spark Plugs

You'll recall in this post, I described how the high performance Pulsestar spark plugs from Enerpulse blew out the ignition coil on my 2002 Prius. I sent in the coil and the plugs to Enerpulse and requested they make good on their guarantee that their plugs would not harm your engine by reimbursing me for the cost of the plugs and the repair. To my surprise, I received a very nice letter from Enerpulse apologizing for the damage and a check reimbursing me for the cost of the repairs and the plugs.

It seems that some instances of their older plugs occasionally had a problem with resistance growing over time, and if the resistance becomes high enough, it causes the plug to wear down fast and eventually misfire, which can then cause damage to the coil. This explains the rapid deterioration in mileage and performance I was seeing over the summer, followed by the catastrophic failure.

They also offered a 10% discount on their new G3 version of the Pulstar plugs. These have improved lifetime and better performance. I am tempted, since the torque and pickup on the 2002 Prius is terrible, but after one bad experience with the product I am not sure whether it makes sense to try it again. I still have a set of their original plugs in my 2008 Prius, so far, they seem to be performing fine.