Posted by Max Dunn
Tue, 12 Feb 2008 20:32:09 GMT | 2 comments
I should ride my bike more. It is good exercise and saves the environment. However, I don’t like to ride my bike on everyday errands.
I was reminded of this today when I got new tires for our car. Like usual, I threw my bike in the back and rode home after dropping off the car. It isn’t far, about 2.5 miles, but I was hot and sweaty when I got home. I was smart this time and brought a piece of string to wrap around my pant leg. Usually I forget this and wind up getting chain oil on my pant leg.
When the car was ready, I rode back to the shop to pick it up, and I was a bit tired.
So it certainly worked out fine to ride my bike, but it isn’t something that I would normally do. Also, for the same reasons, I don’t think we can expect many Americans to forgo their cars and start doing a lot more bike riding either. Good thing I have my electric scooter to scoot around on!
Posted in Random Thoughts, Electric Vehicles, Global Warming, Peak Oil
Posted by Max Dunn
Wed, 06 Feb 2008 02:15:27 GMT | 4 comments
Regardless of what Bush thinks, hydrogen powered vehicles are not a viable alternative.
First off, hydrogen is not something that can be “mined”, but instead must be produced using other energy sources [1]. With current technologies, electricity from hydrogen fuel cells is four times more expensive than electricity from the grid [2]. Secondly, hydrogen is very difficult to ship and store. Leave a hydrogen car at the airport for two weeks and half of the fuel will be lost due to evaporation [2]. Thirdly, while hydrogen fuel cells are clean, currently hydrogen fuel cells are costly to produce and fragile [3] and only about 50% efficient [4]. Lastly, hydrogen is not very dense so cars would need to have a tank 2-3 times larger than their gasoline tanks [3].
With all things considered, it doesn’t make sense to power cars with hydrogen; instead, just put batteries in the car and use the electricity directly.
References:
Posted in Electric Vehicles, Sustainable Energy
Posted by Max Dunn
Mon, 04 Feb 2008 18:20:52 GMT | 4 comments
Ron Freund, past Chairman of the Electric Auto Association, took a survey of 116 RAV4 -EV owners to see how they liked driving a battery electric vehicle (BEV) in general, and in specific, how their experience with the RAV4-EV has been. This is a great reference for anyone interested in how a BEV performs in the real-world. Some of his conclusions are:
- Users frequently commented that the RAV4 has been the best car they ever owned
- The RAV4-EV dependability is remarkable
- The technology is working, no more research is needed
- It is a tragedy that the choice for BEVs does not exist in the market today
Living with a BEV: A Survey of User Experiences
Posted in Electric Vehicles
Posted by Max Dunn
Thu, 31 Jan 2008 00:28:42 GMT | 5 comments
What is with this vehicle-to-grid (V2G) stuff? Why is everyone so excited about it? I already showed how using batteries to store energy at night when it is cheap and then use it during the day doesn’t make sense economically1.
However, this is only part of the picture. It turns out that electricity generation is very complicated, in large part because there is no real storage on the electrical grid. Think about this: what happens when the power plants on the grid don’t produce enough electricity? There will be brownouts or blackouts, both of which are bad. But what happens when they produce too much electricity? Where does it go? Well, actually, since there is no real storage on the grid, it can’t go anywhere, so this is bad.
Read more...
Posted in Electric Vehicles
Posted by Max Dunn
Fri, 25 Jan 2008 01:40:03 GMT | no comments
There are several better energy alternatives to power cars than using gas. The top ones are hydrogen, air or battery. However, it turns out that there are big differences in the efficiencies of these technologies. For 100MJ of input electricity, this is how far each of these cars could go: [18]
- 133 km: Lithium-ion battery vehicle
- 46 km: Compressed air car
- 42 km: Fuel cell vehicle
So it turns out that battery electric vehicles are 3 times more efficient than either compressed air or fuel cell vehicles!
Read more...
Posted in Electric Vehicles
Posted by Max Dunn
Wed, 23 Jan 2008 18:33:26 GMT | 8 comments
I don’t have a lot of confidence in PG&E. It seems that every time we have a big storm, our power goes out. Once, it took 3 days for them to get the power back on! So I have been considering installing a battery backup system for my house to get through these power outages.
If I install a battery backup system, I was wondering if it would be profitable to charge up the batteries at night when electricity costs are low, at $0.05/kWh, and then use it during the day when electricity costs are high, at $0.11/kWh to $0.29/kWh [9]?
Read more...
Posted in Electric Vehicles, Sustainable Energy
Posted by Max Dunn
Wed, 09 Jan 2008 19:43:05 GMT | no comments
It turns out that lithium is not very abundant or easy to mine, and that the price is going up. In this paper, the author even argues that there is not enough lithium available in the world to convert all cars over to plug-in hybrid (PHEV) if we expect to use lithium batteries in them:
The Trouble with Lithium – Implications of Future PHEV Production for Lithium Demand
Posted in Electric Vehicles
Posted by Max Dunn
Wed, 09 Jan 2008 18:39:28 GMT | no comments
An revolutionary new technology is being developed by Stanford researcher Yi Cui that could could generate 10 times more energy from lithium-ion batteries. The trick is that instead of using carbon anodes, they use silicon nanowires because silicon can hold large amounts of lithium atoms. The nanowire technology allows these small wires to swell to four times their normal size without breaking. [1]
When Cui’s paper was originally submitted six months ago, they had only achieved 30 charge-discharge cycles. Since that time however, Cui’s team has pushed the battery through 1000 cycles. [2]
Ultimately, these batteries should be cheap to build. However, they are probably 5 years away from being commercialized. [3]
In reality though, the “10 times more energy” figure is just the theoretical charge capacity increase in the silicon anode, so a real production battery won’t see that much improvement. But even if it improves the overall energy density of a lithium ion battery by 2 or 3 times, that would still be very significant.
[1] Nanowire battery can hold 10 times the charge of existing lithium-ion battery
[2] New Nanowire Battery Life Reaches From iPods to Electric Cars
[3] GM-Volt.com: Interview with Dr. Cui, Inventor of Silicon Nanowire Lithium-ion Battery Breakthrough
Posted in Electric Vehicles
Posted by Max Dunn
Sun, 30 Dec 2007 17:43:32 GMT | 1 comment
When I talk about how clean electric vehicles are, people sometimes ask if they really do reduce greenhouse gases since burning coal to produce electricity creates a lot of CO2. My standard answer to this question is that even in the worst case, electric cars are twice as clean as gas powered cars. However, while reading an article in Forbes about vehicle-to-grid (V2G) systems. I realized that in general, electric cars are much cleaner than even this.
This article had an interesting chart that said electric cars produce about 1.1 tons of greenhouse gases a year while gas powered cars produce 6.3 tons – over 6 times more! Let’s see if we can verify these numbers.
The average car is driven 15,000 miles per year and electric vehicles normally get 4 miles per kWh, so it takes about 3,750 kWh of electricity a year to power an electric car. In California, the mix of electricity production produces about 0.6 lbs of greenhouse gases per kWh so this would produce 2,250 pounds, or 1.1 tons of greenhouse gases – right on the money with the Forbes chart.
A gas car, on the other hand, produces about 1 lb of CO2 for every mile driven (based on producing 20 lbs per gallon and getting 20 mpg). So 15,000 miles would produce 15,000 lbs of greenhouse gases, or about 7.5 tons – which is more than the Forbes estimate of 6.3 tons (maybe they are using a higher mpg).
So electric cars are even cleaner than I had thought, producing about one sixth as much greenhouse gases as a gas car.
Posted in Electric Vehicles, Global Warming
Posted by Max Dunn
Tue, 04 Dec 2007 17:15:19 GMT | 2 comments
That is the question – whether to buy a low-speed electric vehicle now, or wait for a high-speed electric vehicle later? Here are the factors I am looking at:
- What type of transportation do I need?
- When will high-speed electric vehicles really arrive?
- How much will they actually cost?
- When will the severe oil shortages start?
- Will there be subsidies for electric vehicles?
The short answer is that I am going to buy a low-speed NEV now and wait for later to buy a freeway capable electric car. Here is the long answer:
Read more...
Posted in Electric Vehicles, Peak Oil