Hype about Hydrogen
For all the buzz about future highways filled with hydrogen-powered fuel-cell cars, the technological-and environmental-high ground will belong to gasoline-electric hybrids for decades to come.
Hydrogen and fuel-cell cars are being mightily promoted. The U.S. Department of Energy has made them the central focus of its clean energy efforts. The state of California has said it will in the next few years build a “hydrogen highway,” with hydrogen fueling stations every 20 miles along major highways. General Motors is spending more than a quarter of its research budget on fuel cell vehicles and Larry Burns, GM’s vice president for R&D and planning, said in February that the company will have a commercially viable fuel cell vehicle by 2010.
Yet for all this hype, hydrogen cars are likely to remain inferior to the best gasoline-electric hybrid vehicles such as the Toyota Prius in virtually every respect-cost, range, annual fueling bill, convenience, safety-through at least 2030. The Prius will even have lower overall emissions of many pollutants than cars running on the hydrogen that is likely to be available at fueling stations for the foreseeable future. And a premature push toward hydrogen cars would undermine efforts to reduce the heat-trapping carbon dioxide emissions that cause global climate change.
For hydrogen cars to become both practical from a consumer’s perspective and desirable from an environmental perspective will require at least three major technology breakthroughs. In addition, the nation will have to shift its energy policy dramatically toward renewable energy sources such as wind and solar.
Don’t get me wrong. I am a strong proponent of hydrogen as a possible fuel for the future. In fact, I helped oversee the Department of Energy’s program for clean energy, including hydrogen, for much of the 1990s-during which time we increased funding for hydrogen technologies tenfold. I believe that continued research into hydrogen remains important because of its potential to provide a pollution-free substitute for oil post-2030.
But going beyond R&D at this point to actually building the hydrogen infrastructure-as many advocate-is both unjustified and unwise. As Peter Flynn, an engineering professor at the University of Alberta, concluded in a 2002 study of the effort to commercialize natural gas vehicles: “Exaggerated claims have damaged the credibility of alternate transportation fuels, and have retarded acceptance, especially by large commercial purchasers.”
Let’s briefly look at why hydrogen cars are still a long way from making sense.
In a “hydrogen economy,” the main energy carrier would be hydrogen that is produced from pollution-free sources of energy. This goal rests on two pillars: a pollution-free source for the hydrogen and a device for cleanly converting this hydrogen into useful energy (the fuel cell).
Hydrogen is not a readily accessible energy source like coal or wind. It is bound up tightly in molecules like water (H20) and natural gas (primarily composed of methane, or CH4) so it is expensive and energy-intensive to extract and purify. More than 95 percent of U.S. hydrogen is produced from natural gas today because that is the cheapest method. Yet delivering hydrogen from natural gas to the tank of a fuel-cell car in usable form costs four times as much as gasoline with an equivalent amount of energy. Hydrogen from pollution-free sources, such as renewables, is even more expensive. A hydrogen infrastructure built around existing or near-commercial technologies would cost more than $600 billion, according to the most comprehensive study done, by the Argonne National Laboratory.
Fuel cells are small, modular, electrochemical devices, similar to batteries, but which can be continuously fueled. A fuel cell takes in hydrogen and oxygen and puts out electricity and heat; its only “emissions” are water. This sounds like an energy panacea-but today, more than 160 years after the first fuel cell was built, and after more than $15 billion in public and private spending, fuel cell technology still has not achieved major commercial success.
The technical challenges are enormous. In September 2003, a U.S. Department of Energy panel on basic research needs for the hydrogen economy, chaired by MIT professor of physics and electrical engineering Mildred Dresselhaus, reported that transportation fuel cells are 100 times more expensive than internal combustion engines. The most mature hydrogen storage systems-using ultrahigh pressure-contain seven to 10 times less energy per unit volume than gasoline, and require a significant amount of compression energy. Just last month, a prestigious National Academy of Sciences panel concluded that such storage has “little promise of long-term practicality.” And a report published this month by the American Physical Society concluded that “a new material must be discovered” to solve the storage problem.
The Department of Energy panel noted that the cost of producing hydrogen would have to be reduced by a factor of four to make hydrogen economically competitive with today’s fossil fuels. Major advances would also be required in hydrogen infrastructure and safety. The panel concluded that these gaps “cannot be bridged by incremental advances of the present state of the art,” but instead require “revolutionary conceptual breakthroughs.”
If this sounds like it will be a long time before we see a commercially viable product in the marketplace, that should be no surprise. Breakthroughs that revolutionize energy technology are rare. It has taken wind power and solar power each about 20 years to see a tenfold decline in prices, after major government and private-sector investments in R&D and deployment-and they still account for well under one percent of U.S. electricity generation.
Alternative fuel vehicles (AFVs) are a greater challenge, because they must overcome a trillion-dollar investment in the gasoline fueling infrastructure. Two major efforts to commercialize AFVs in the past two decades-electric vehicles and natural gas vehicles-both failed, even though electricity and natural gas are widely available and inexpensive. Hydrogen, by contrast, is hardly available anywhere and is relatively expensive. Our cars and our fueling infrastructure are designed around liquid fuels, which have high energy densities and are easier to handle than diffuse gases like hydrogen.
Based on my discussions with experts around the country, I think it unlikely that hydrogen cars will achieve even a five percent market share by 2030. But we shouldn’t be in a hurry to deploy hydrogen cars.
It’s Not Necessarily Clean
It is a popular misconception that hydrogen is inherently good for the environment. But in fact, hydrogen is no greener than the energy sources used to produce it. As the National Academy panel noted, “It is highly likely that fossil fuels will be the principal sources of hydrogen for several decades.” Any premature push toward hydrogen cars would inevitably mean the hydrogen would come from the cheapest source today, natural gas. Yet, given the constraints on the North American gas supply, we would just be trading imported gas for imported oil.
More important, a fuel-cell car running on hydrogen derived from natural gas offers no significant greenhouse gas savings compared to running advanced hybrid vehicles on oil-as a 2003 MIT study concluded. The best new hybrids have sharply reduced their fuel consumption and hence greenhouse gas emissions. Running on low-sulfur gasoline, the 2004 Prius produces 90 percent less tailpipe emissions than the average new car.
The least expensive hydrogen, however, is dirty. Based on the hydrogen fueling stations Royal Dutch/Shell has proposed to build, the total emissions of nitrogen oxides from a fuel-cell vehicle would be triple that of the best new cars.
Equally important, such a strategy would divert natural gas from a variety of better uses. While vehicles running on natural gas-derived hydrogen won’t provide significant greenhouse gas reductions compared to the best hybrids running on gasoline, a switchover to natural gas can greatly reduce the emissions from electricity generating plants. A coal-fired generator releases more than 1,000 kilograms of carbon dioxide into the air for each megawatt-hour of electricity it produces. The best gas-fired plants, by contrast, release only about 350 kilograms of carbon dioxide per megawatt-hour generated.
Similarly, one megawatt-hour of electricity from renewables, if used to make hydrogen for a fuel-cell vehicle, would save around 230 kilograms of carbon dioxide compared to a Prius running on gasoline. That is some 770 kilograms less than the savings from displacing coal power-and these savings can be achieved without spending hundreds of billions of dollars on fuel-cell vehicles and hydrogen infrastructure. As David Keith of Carnegie Mellon and Alexander Farrell of the University of California, Berkeley, concluded in a July 2003 analysis in Science magazine: “Until CO2 emissions from electricity generation are virtually eliminated, it will be far more cost-effective to use new CO2-neutral electricity (e.g., wind or nuclear) to reduce emissions by substituting for fossil-generated electricity.”
The U.S. Congress, however, won’t pass legislation requiring even 10 percent of electricity in 2020 to be from renewables. This means that hydrogen cars will have no real value as a global warming strategy until after 2030. A 2004 analysis by Pacific Northwest National Laboratory concluded that even with technology breakthroughs and a big push on reducing carbon dioxide emissions, “hydrogen doesn’t penetrate the transportation sector in a major way until after 2035.”
Right now, delivering renewable hydrogen to a car in usable form is prohibitively expensive-equivalent to gasoline at $6 to $10 a gallon. We need a major breakthrough in CO2-neutral hydrogen production, along with significant leaps forward in fuel cells and hydrogen storage, before hydrogen cars will be plausible competitors.
While we’re doing the R&D over the next two decades, we must, if we are to avoid catastrophic global warming, make new CO2-neutral electricity our top priority. A March 2003 analysis by a group of scientists led by Ken Caldeira of the Lawrence Livermore National Laboratory, and published in Science magazine, concluded that “if climate sensitivity is in the middle” of the currently projected range, “even stabilization at 4C warming would require installation of 410 megawatts of carbon emissions-free energy capacity each day”-five times the business-as-usual forecast.
While hydrogen vehicles might have limited value replacing fleets powered by diesels engines in very polluted cities before 2030, fuel-cell cars are unlikely to achieve mass-market success by then. Neither government policy nor business investment should be based on the belief that hydrogen cars will have meaningful commercial success in the near or medium term.
Become an MIT Technology Review Insider for in-depth analysis and unparalleled perspective.Subscribe today