This isn't exactly an overnight revolution, then. However, BART notes that it would actually outperform California's plans for a standard of 50 percent renewable energy use by 2030. Also, any improvements will likely make a tangible impact on the state. BART uses more power than the entire city of Alameda (over 400,000MW/h per year) -- even that 2025 target might help a lot. It's also important to note that BART expects to run both trains and its infrastructure on green energy sources. The area's Caltrain service has already made its own pledge to use renewable energy, but it's still using diesel trains where BART's vehicles are completely electric.

Only some of this will come through in-house energy generation (primarily through solar power), since BART just wouldn't have the capacity to meet all its own demand. Most of it will come by purchasing energy from the grid. There will be a certain point at which you can ride the train largely guilt-free, however, and whatever BART accomplishes might help other transportation networks achieve their own renewable energy goals.