MIT study finds diesel hybrids offer better efficiency and GHG emissions than fuel cell vehicles

7 March 2003

A new study by the Massachusetts Institute of Technology (MIT) concluded that diesel hybrids will be better than hydrogen fuel cell vehicles in terms of total energy efficiency and greenhouse gas emissions until at least 2020. The study—authored by Malcolm Weiss, John Heywood, and co-workers—was published by the MIT’s Laboratory for Energy and the Environment (LFEE).

And while hybrid vehicles are already appearing on the roads, adoption of the hydrogen-based vehicle will require major infrastructure changes to make compressed hydrogen available. If we need to curb greenhouse gases within the next 20 years, improving mainstream gasoline and diesel engines and transmissions and expanding the use of hybrids is the way to go, according to the study. These conclusions were released just a month after the Bush administration announced a billion-dollar “FreedomFUEL” initiative to develop commercially viable hydrogen fuel cells and a year after establishment of the government-industry program to develop the hydrogen fuel-cell-powered “FreedomCar”.

The study assessed a variety of engine and fuel technologies as they are likely to be in 2020 with intense research but no real “breakthroughs”. The new assessment is an extension of a study done in 2000, which likewise concluded that the much-touted hydrogen fuel cell was not a clear winner. This time, the MIT researchers used optimistic fuel-cell performance assumptions cited by some fuel-cell advocates, and the conclusion remained the same.

The hydrogen fuel-cell vehicle has low emissions and energy use on the road, but producing hydrogen from a hydrocarbon fuel such as natural gas or from water using fossil fuel-derived electricity requires substantial energy and produces greenhouse gas emissions. The “well-to-wheel” analysis performed by MIT included not only tailpipe emissions, but also the emissions and energy used in making and delivering the fuel and in the manufacturing the vehicles.

Hydrogen-fueled vehicles, however, may show an advantage over longer time frame, beyond 2020. “If auto systems with significantly lower greenhouse gas emissions are required in, say, 30 to 50 years, hydrogen is the only major fuel option identified to date,” said Heywood. The hydrogen would have to be produced without making greenhouse gas emissions from a non-carbon source such as solar energy or from conventional fuels while sequestering the carbon emissions.

Source: MIT