Last week, I reported that Vancouver’s Mayor Sam Sullivan says that we need density to reduce greenhouse gas emissions. Similarly, Salt Lake City’s Mayor Rocky Anderson says that his region should build more light rail in order to reduce greenhouse gas emissions.
Both of these ideas are wrong. Building light rail is increasing greenhouse gas emissions in Salt Lake City. Building high-rise condos instead of single-family homes is increasing greenhouse gas emissions in Vancouver.
Let’s start with light rail. According to the National Transit Database, Salt Lake City’s light-rail lines consumed 17.4 million kilowatt hours of electricity in 2005, which works out to 2,676 BTUs per passenger mile. Salt Lake’s buses consumed 4.6 million gallons of Diesel fuel, which works out to 8,527 BTUs per passenger mile.
That makes light rail look pretty good. The catch is that the light-rail system would not work without a supporting bus system. So we can’t compare today’s light rail with today’s buses. Instead, we have to compare today’s light-rail and bus system together with the bus system that existed before light rail was built.
When considered together, Salt Lake’s transit system consumed 5,574 BTUs per passenger mile. But before light rail was built, Salt Lake’s bus system was consuming less than 4,300 BTUs per passenger mile. By cherry picking the best bus routes and draining passengers away from bus lines, light rail led to an increase in energy consumption.
Most electricity in Utah comes from burning coal. According to the Department of Energy, each kilowatt hour of electricity from Utah and Wyoming coal-fired power plants produces about 2 pounds of CO2. Meanwhile, the EPA says that a gallon of Diesel produces about 22 pounds of CO2.
Running these numbers through, it turns out that Salt Lake’s transit system today emits .9 pounds of CO2 per passenger mile. By comparison, the transit system before light rail was built produced less than 0.7 pounds of CO2 per passenger mile. (The average automobile emits about 0.56 pounds of CO2 per passenger mile.)
Now, someone might argue that light rail has reduced CO2 by taking people out of their cars. But my argument is that improvements in bus service would take as many people out at a far lower cost. Mayor Anderson’s argument is that, in spite of this, the city should build light rail to reduce greenhouse gas emissions. He is wrong.
Mayor Sullivan says that density reduces greenhouse gas emissions. But you couldn’t prove it by Vancouver. Over the last decade, the region has steadily increased its population density by more than 1 percent per year. Yet a travel survey conducted by the regional transportation authority found that auto trips per capita have also been increasing by more than 1 percent per capita.
How about housing? I’ve haven’t yet found data showing whether the construction of high-rise housing uses more energy per housing unit than single-family homes. However, a study from Australia finds that operating high-rise apartments produces more greenhouse gases than single-family homes. Moreover, because high rises tend to attract smaller households, emissions per capita are almost twice as high as for single-family homes.
So more work is needed, but as usual it turns out that the density advocates are probably wrong. Unfortunately, by the time we prove that density is bad (or at least no better than suburbia) for global warming, they will come up with some other lie to support their social engineering.