In the struggle of offering the most environmental friendly public transports, life cycle analysis is a good tool for comparing concepts.
In order find the most favourable rout from energy source to public transport vehicles, the chain of energy conversion from well-to-wheel is analysed.
In this way it is possible to justify the use of green energy. Often however it is forgotten that the green energy, today might be used in an even more efficient way by other energy consumers with less resources. According to IEA the energy use globally will increase by 50% the next 20-30 years. In parallel FAO forecasts a need for production of twice as much food as we use today globally.
Favourable paths from well-to-wheel are not hard to find by “tunnel view” disregarding the indirect consequence for other energy consumers.
For example, biomass in general will for many years to come have efficient use in the combined heat and power generation. To point out the public transport sector to pirate whichever energy source that is considered to be the most environmentally friendly choice for the time being will on one hand be counter productive since it will raise the cost for the public transports and hence limit the amount offered, on the other hand for buses it will in the first approximation not make much harm either, since its by far the most energy efficient way to provide transports of persons. The positive side of the interest in biofuels is that an increased interest in sustainable energy in general in the long time perspective will increase the production.
But, we do not need to perform the full lifecycle analysis for the planet as a whole before we act. By knowing that the energy market is very “volatile” saying that the one selling energy readily will sell it to the one paying the highest price, as a bus manufacturer we can focus on providing the most energy efficient bus. By providing less energy use, we ensure that the bus we provide also make a positive environmental impact on the global level!
Bus life cycle environmental cost (with costs from the new European directive for “Promotion of green and energy efficient vehicles”). The Volvo 7700 Hybrid will use 30 % less energy for most city buses. In the picture above we use 20% reduction of the fuel consumption to cover also commuter traffic. The “City Bus” is a standard diesel bus.