If petroleum-based fuels are not the future for the transportation industry, what will take their place? Today, biofuels play a significant role, moving a portion of the nation's energy supply away from traditional gasoline and diesel. But, concerns surrounding the amount of farmland used to produce these biofuels rise, it becomes increasingly unlikely that biofuels will be able to eliminate our reliance on petroleum-based fuels. Some support hydrogen as a source of energy for the transportation sector. But, as Sheril Kirshenbaum explains, when it comes to hydrogen, "we're not there yet."
One of the perks of being a Hill staffer is access to cool new technologies when lobbyists visit. And so in 2006, I looped around D and 2nd in a hydrogen car. When I asked the nice man who brought the vehicle about safety and the inherent ‘chicken and egg’ problem (cars and fueling stations – which comes first?), he provided a clearly scripted response intended to brush off public concerns. I was sure he’d repeated it dozens of times that afternoon and–needless to say–I wasn’t convinced.
You see, despite all the hype, hydrogen is unlikely to become a significant source of energy. I’ll explain what makes this energy carrier appealing, followed by outlining its detractors, especially regarding use in personal vehicles.
Hydrogen has superior energy density compared other fuels (a whopping 120 MJ/ kg in the liquid form). You may remember that George W. Bush often brought up the way its combustion yields water avoiding emissions. He committed over $1 billion to the development of a hydrogen car. And it’s true that fuel cells can produce electricity with high efficiency and no moving parts. They are quiet and can also be designed at different scales depending on intended use. So far, so good.
BUT hydrogen is not available in enormous reservoirs in the Earth’s crust and requires energy for production. Although current high cost and unreliability should become less prohibitive as technology improves, the distribution issues that would be required for use in personal cars are more difficult to overcome. On top of that, liquid hydrogen must be maintained below -241 C so storage poses problems. Finally, there’s the enormous elephant in the room: Safety. Hydrogen is highly flammable with an ignition energy 1/10 of gasoline.
So yes, the prospect of using hydrogen has some appeal. It’s most plausible in fleet vehicles like buses which would require fewer filling stations. However, it’s unlikely we’ll all be whizzing around in our own personal hydrogen cars anytime soon.
About the Author:
Sheril Kirshenbaum is a science writer and research associate at the Center for International Energy and Environmental Policy at the University of Texas at Austin. She is the author of two books - "Unscientific America: How Science Illiteracy Threatens our Future" and "The Science of Kissing." Sheril currently blogs at Culture of Science.
[A version of this post was previously published on June 6, 2010]