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Do electric cars cause more or less climate pollution than gasoline cars? Take a look.

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  • 102 tCO2 = drive existing average car
    Emissions from burning the gasoline to drive the full 320,000 km lifespan.
  • 60 tCO2 = recycle and replace with Pruis
    Building and driving a Prius causes 53 tCO2. Add to that the 7 tCO2 from building the average car that we decided to recycle. Total is 60 tCO2.
  • Result = extra 52 tCO2 to keep driving average car

That extra 52 tCO2 is for the entire lifespan of the average car. In the case where the average car has 10% of its lifespan remaining (~32,000km) choosing to "keep driving it" will cause 10% of that extra climate pollution = 5.2 tCO2.

Of course this discussion is mostly just an academic exercise because very few people today will recycle a car that has lots of kilometres remaining. Even if those km are very dirty. The owner would be throwing away value if they did.

This highlights the rapidly growing threat of "locking in" future climate pollution that the International Energy Agency has been warning about. They says we are just four years away from building so much expensive fossil fuel demanding infrastructure that we will "lock in" dangerous levels of climate pollution.

This threat of "locking in" too much future climate damage is also at the center of the Keystone XL pipeline battle.

Q: How can I find the climate pollution from my region's electricity?

A: The most accurate source is your electricity supplier. For ballpark estimates try carma.org.

DISCUSSION:  Renewable sources of electricity like solar, wind, hydropower and geothermal create little climate pollution. Burning fossil fuels like coal, natural gas and oil to generate electricity creates large amounts of climate pollution.

If you can't find the information from your local electricity supply you can use a quicker, but more ballpark source: www.carma.org. It lists the "intensity" of electricity production for just about every power plant, province, state and nation. The "intensity" they list is in terms of kgCO2/MWh. To convert to tonnes of CO2 per kWh, divide by one million.

For example, Carma.org lists BC electricity at 23 kgCO2 per MWh which is very close to what the province's electricity supplier (BC Hydro) says it is: 26 kgCO2 per MWh. I used carma.org data for regions I didn't have other sources for.

Q: How much will I reduce my climate pollution by using public transportation?

A: Using public transportation or car sharing could either dramatically decrease -- or increase -- your climate pollution. It all depends on type of vehicle you travel in and how many people are in it.

DISCUSSION: Public transportation ranges from very low levels of climate pollution per passenger (ex: electric buses in clean electricity regions) to extremely high levels of climate pollution per passenger (ex: airlines).

For example, here is a sampling of the tonnes of climate pollution per passenger caused by a round trip from Vancouver BC to Los Angeles:

  • 2.0 tCO2 = average airline (first class)
  • 1.0 = average airline (economy class)
  • 0.6 = SUV or van with two people
  • 0.4 = average car with two people
  • 0.4 = Canada/USA railroads
  • 0.2 = regular Prius with two people
  • 0.1 = bus with 30 people

The best and the worst are public transportation. The worst in this list (first class flight) is 20 times more climate polluting than the best (bus). Driving a car has nearly as wide a range depending on the type of car and the number of passengers in it. Click here for my Visual Carbon chart showing many more alternatives for this scenario.

I've done less research on the climate pollution from city bus and light rail for short trips in a city. My guess is that buses and light rail are the least climate polluting, especially if powered by clean electricity. I usually opt for one of these or riding my bike. But it is an area I need to research more before I can say with any confidence.   

Geeky details

Here are a few points for those that like the data details:

  • Amazingly there are even more climate polluting vehicles than the worst on my chart. These include gasoline-only versions of heavy-duty pickup trucks, some high-end sports cars and larger passenger vans.
  • Electric motors require only a half to a third of the energy (joules) as a gasoline engine. Much of the energy in gasoline engines is wasted as heat.
  • Electricity from Alberta causes around 100 times more climate pollution per kWh than electricity from Quebec.
  • Plug-In hybrids allow direct comparison between the efficiency of electricity and of gasoline in the same car.
  • I chose the Toyota Prius Plug-In as the example plug-in hybrid in my chart because it allows a close comparison to what the US EPA says is the least climate polluting gasoline-only car: the regular Toyota Prius.
  • The percentage of km driven on gasoline vs electricity for a plug-in hybrid varies across drivers. The US EPA estimates 40 to 60 percent of miles will use gasoline for typical plug-in hybrid. For my chart I picked 60 percent.
  • The US EPA now lists how efficient electric-fuelled vehicles are. This ranges from 29 kWh to 54 kWh per 100 miles.
  • EPA lists the US fleet average in 2010 at 21.6 mpg. The average for new cars in 2013 is listed at 23 mpg.
  • The California Air Resources Board studied how long vehicles actually last. They determined the average passenger car lasts 202,329 miles and the average light-duty trucks last 223,969 miles. I used 200,000 miles (321,000 km) in my chart.
  • My chart uses the "wells-to-wheels" emissions for gasoline. According to the US Department of Energy this adds an extra 24 percent.

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