“cars have become far more energy efficient in the last fifty years while transit has become less energy efficient. According to the Department of Energy, the average car used close to 4,900 British thermal units (BTUs) per passenger mile in 1970, dropping to 3,100 today. Light trucks, which include pick ups, full-sized vans, and sports utility vehicles, use about 3,500 BTUs per passenger mile. The energy used by transit buses, however, increased from under 2,500 BTUs per passenger mile in 1970 to more than 3,800 today. Energy consumption by rail transit, including light rail, heavy rail, and streetcars, grew from under 2,200 BTUs to nearly 2,400 BTUs per passenger mile.
Light rail tends to be less energy efficient than heavy rail, on average using more than 4,000 BTUs per passenger mile in 2015 compared with under 2,000 for heavy rail. Metro Transit’s light-rail lines are even less energy efficient than average, using more than 4,100 BTUs per passenger mile in 2015. The Northstar commuter trains used nearly 3,200 BTUs per passenger mile in 2015. When all Twin Cities transit is counted together, including transit provided by agencies other than Metro Transit, transit used more than 4,300 BTUs per passenger mile in 2015. In short, Twin Cities transit uses more energy per passenger mile than the average SUV.
The emissions of toxic air pollutants are more difficult to calculate because they depend on many factors, including the type of technology used to control emissions, the age of vehicles, and how well maintained they are. In general, diesel-powered buses produce more particulates and nitrogen oxides per passenger mile than cars, while producing slightly less carbon monoxide and volatile organic compounds. The diesel-powered Northstar commuter train is likely to be a heavy polluter. Minnesota still gets more than half of its electrical power from burning fossil fuels, and this also results in more pollution.
Estimating greenhouse gas emissions is more straightforward because the emissions from most fuels are proportional to the BTUs consumed. Burning gasoline produces 0.071 grams of carbon dioxide per BTU, so the average car emits about 220 grams per passenger mile. Diesel produces slightly more, 0.073, grams per BTU. Metro Transit uses between 5 and 20 percent biodiesel from soybeans. It is debatable whether this reduces greenhouse gas emissions since production of soybeans themselves results in greenhouse gas emissions. Generously assuming that Metro Transit uses 20 percent biodiesel and that this reduces emissions from that 20 percent by 75 percent, then buses emit 0.062 grams per BTU. Since Metro Transit buses use about 3,475 BTUs per passenger mile, they emit at least 215 grams per passenger mile.
In 2015, 43 percent of the electricity generated in Minnesota came from burning coal, while another 13 percent came from natural gas. This means that, on average, Minnesota electricity generated about 0.048 grams of carbon dioxide per BTU. Since light rail used about 4,100 BTUs per passenger mile, it produced nearly 200 grams of carbon dioxide per passenger mile. The diesel-powered Northstar commuter train produced about 230 grams per passenger mile in 2015.
In short, Twin Cities transit does not produce significantly more greenhouse gas emissions per passenger mile than cars, but neither does it produce significantly less. The construction of light-rail lines generates huge amounts of greenhouse gases that will never be recovered from savings from light-rail operations. If the Metropolitan Council were seriously interested in saving energy or reducing greenhouse gas emissions, it would focus on encouraging people to buy and drive more fuel-efficient cars, not on getting a handful of people out of cars and onto transit vehicles that don’t save energy anyway.”