Pet Peeve of the Day: Zero Emissions Vehicles

Zero Emissions Vehicle? There is no such thing.

Aha you say, what about a bicycle? Nope, you exhale CO2 at a greater rate when pedaling than when at rest, so there is some climate change penalty. Not a whole lot, but most of the beneficial effect is because you are only moving the mass of a bicycle around and not an automobile. (The human body produces about 70-80 kg of CO2 per million BTU.)

A bicycle is not really practical anyway. I rode my bicycle to work every day for about 5 years. That was only practical because my family also had a car that could be used for shopping, taking kids to school and soccer practice, and for taking trips. The bicycle is nice, but in suburbia you need a car to supplement it.

What about the real Zero Emissions Vehicles, electric cars? There are zero emissions coming out their tailpipes - they don't even have tailpipes - so it looks good at first. They use nice, clean electricity.

So how much CO2 is produced by electricity production. That depends on the fuel used to produce the electricity. Here are some typical values for CO2 produced by burning various fuels:

• coal = 95-104 kg per million BTUs
• fuel oil = 73 kg CO2 per million BTUs
  
• natural gas = 54 kg CO2 per million BTUs

The fuel mix varies for different regions of the country. The overall average for CO2 produced for electrical generation in the U.S. in 2004 was 182 kg CO2 per million BTU. Hey, wait a minute. Why is the average bigger than any of the typical values? The average is how much CO2 was generated per million BTUs electricity produced, while the typical values are the amount of CO2 generated per million BTUs heat generated from burning the fuel. Not all of the heat gets converted to electricity. At least that is what I surmise from reading the 168 pages of instructions for Form EIA1605.

So what? Is that a big number or a small number? Let's compare it to the kg CO2 produced by driving a gasoline engine powered car. Gasoline produces about 71 kg CO2 per million BTU or about 8.8 kg CO2 per gallon of gasoline. The average car uses 370 watt-hr to travel 1 mile. Let's assume our car averages 20 miles per gallon. So it is using (8.8 kg CO2 / gallon ) x (1 gallon / 20 mile) x (1 mile / 370 watt-hr) x (1 watt-hr / 3.41 BTU) = 349 kg CO2 per million BTU.

At first glance, the zero emissions vehicle appears to be a half the emissions vehicle. That's certainly an improvement, but it is not anywhere close to zero. There are also a few things we have not considered, like electrical transmission losses (around 7%) and storage, but we also have not considered the effects of trasnporting gasoline either.

Back to my pet peeve. They are not Zero Emissions Vehicles. Maybe they are Half the Emissions Vehicles, but I think the main attraction for most people is they are NIMBY Emissions Vehicles.