Want An Electric Vehicle?

by Bill Creasy

Climate change is a problem that should receive more attention by average Americans [1]. One way to try to decrease contributions to carbon dioxide emissions contributing to global climate change is to switch from vehicles using petroleum fuels to those powered by electric batteries. The electricity can be generated by solar power or a renewable resource. It is even better if the electric vehicle consumes less energy.

Such a vehicle is commercially available now. It is an electric-motor assisted bicycle, or electric moped.

I bought an electric bicycle last year. There are several models available from two major manufacturers, eZee Bikes and Giant. The models all have typical human-powered pedals assisted by a small electric motor with a rechargeable battery. Some models are small enough to fold up to carry on a train or in a car trunk [2].

I purchased an eZee Torq model, which looks like a normal 27" mountain bike, but with a 10 lb. battery mounted behind the seat and a small electric motor on the front wheel hub. The advantage of the bike is that it has a speed of 20 mph with a range of 25-30 miles. Since I have a commute of 19 miles to work, I can commute on the bike in about an hour, compared to half an hour in a car. On a normal bike, the ride takes about 2 hours, and I'm quite tired when I get there. So the electric bike provides me with the option of riding to work rather than driving.

Obviously, a bicycle uses less energy than a car because it weighs less. How much less? Using an approximate calculation, a gasoline car generates about 7.5 kW-hrs of useful energy for a 20 mile drive [3]. My bike, for comparison, uses about 0.4 kW-hrs of energy. So I can get to work with about 20 times less energy with the electric bike compared to a car.

I have to add some words of caution. I ride the bike because it's fun. Luckily, the road that I use has a wide shoulder for bicycling out of the traffic. I usually only ride to work one day a week. It saves some gas, but the amount that I can carry to and from work is limited, and it is necessary for the weather to be good and the days to be long.

Since this is WASHline, I should say something more profound about this topic than to just talk about a bike. It is a useful case-study to consider voluntary reductions in fuel consumption. In general, we can say that people have three options: 1) keep on doing everything the same as before and continue consuming as much energy, 2) try to do the same things, but as efficiently as possible, or 3) refrain doing some things entirely.

If everyone keeps doing the same things without changing, clearly it won't address the problem of climate change. Americans will remain the largest per capita emitters of carbon, and everyone else in the world may decide to follow our example and try to catch up, making matters worse. At some point, the climate situation may become so bad that people will have no choice but deal with a catastrophic situation. This is clearly not the good option.

We can do everything we want to, but do it as efficiently as possible. An example is switching to an electric bike. This saves about 1 gallon of fuel per commute. Many of the broader social changes that have been suggested to reduce greenhouse gas emissions fall into this category. Decreasing energy consumption can save money and justify technology improvements. Using electric vehicles can allow a switch to nuclear, solar, or wind power, and away from petroleum dependence.

But this option usually involves inconvenience or investment, as well as requiring the initiative to make a change when it isn't immediately necessary. In the case of the electric bike, I had to buy the bike, ride an hour to work instead of half an hour, and risk getting caught in the rain, to name a few issues. The change required investment in new equipment and less convenience.

The last option is to stop doing some of the things that we take for granted now. Whenever I drive on Rt. 95, I wonder where all the other people on the road are going, and why they don't just stay home. Of course, I'm also on the road going somewhere. In fact, it takes very few trips for me to take to WASH events to consume the fuel that I saved by riding the electric bike. (Within the past week, as I write this, I drove a total of 400 miles to WASH events.) Why should I stay home and not travel, if everyone else is still on the road?

These are not simple ethical questions to address. Before we make routine trips, are we are going to have to consider not only what we want to do, but also the welfare of future generations and of other people in the world? It is not simple to do that.

It would be nice to think that these efforts will happen on a voluntary basis. It seems more likely that manditory restrictions and significant energy taxes will be necessary to change most people's behavior. In the process, many people will be forced to stop doing some things that they would like to do, whether they want to or not.

Notes

1. If you don't believe me, see Stuart Jordon's articles "Global Climate Change Triggered by Global Warming," Skeptical Inquirer, May/June 2007 and July/August 2007, and at www.cfidc.org/opp/jordan.html.

2. The bikes can be found at www.nycewheels.com, and there is a store in New York City.

3. The calculation of how much useful energy a car generates is not trivial. The easiest approximation is to use the chemical energy in gasoline. One gallon of gasoline contains 36.625 kW-hrs of chemical energy when burned. But only about 35% of the energy is useable in an engine, and the rest is lost to heat, giving 12.82 kW-hrs per gallon. For a 20 mile trip that takes 30 min. in a car that gets 34 mpg, 0.588 gal. of gas are consumed, and 7.54 kW-hrs of useful energy is produced by the engine. Of course, much of this energy is lost to friction and air resistance, rather than actually adding kinetic energy to the car. The rest is lost to heat in braking because of slowing down, because at the end of the trip the car stops. A Toyota Prius uses less gasoline largely because it is more efficient at stopping and starting on short trips. A calculation can be found at www.godshome.us/solar/solar.html. (The reason for the name of the site isn't clear.)

The calculation of energy consumption of the electic bike is comparable, though. I used the amount of energy that it takes to charge the battery after a trip, which is analogous to the amount of useful energy in the gasoline of the car.