Guest blogger, Arnold R. Miller, PhD
As president of a company that develops large prototype fuelcell vehicles, such as a 130 t railway locomotive that exclusively utilizes hydrogen as fuel, I’m often asked about the practicality of hydrogen. Many people believe that, because more energy is required to produce hydrogen than can be gotten out of it, hydrogen is not practical. However, this statement is only half true.
Hydrogen is an energy carrier like electricity. About 3 MJ of primary energy is required to produce 1 MJ of electricity. That is, the overall efficiency of electricity production is on the order of one-third, and obviously more energy is required to make electricity than is in the electricity. But few people would conclude from this that electricity is impractical.
High-temperature steam electrolysis can produce hydrogen from water and electricity with a thermodynamic efficiency of about 0.9. Thus, hydrogen production can be nearly as efficient as electricity production. The part of the statement “more energy is required to produce hydrogen than can be gotten out of it” is true, but the part “hydrogen is not practical” is not true for the same reason that such a statement is not true for electricity.
Why do people hold the contrary opinion? It probably stems from the belief that fossil fuels, because they’re pumped from the earth, are “free” in the sense that no energy cost was incurred in their creation. They are viewed as a primary energy. However, the cost of interest is generally not energy cost but monetary cost: it’s because energy inefficiency has an associated monetary cost that we’re interested in efficiency. Monetary cost is also the lingua franca that allows mathematical combination of various costs.
While crude oil itself does not require chemical synthesis, there are many monetary costs along the way to market as a vehicle fuel. Four components of any cost are (a) capital or infrastructure cost, (b) operating cost, (c) maintenance cost, and (d) social cost. Petroleum exploration, oil tankers, and gasoline refineries represent large capital, operating, and maintenance costs. However, the largest cost of fossil fuels is social cost. These include diseases caused by noise and air pollution, global climate change, and wars to protect the supply of crude oil. A number of studies have investigated the true cost of gasoline, which factors in social cost, and one well-known study  calculated the true cost – when the pump price was around $0.25/L ($1/gal) – to be above $3.75/L ($15/gal).
In the final analysis, however, the question of whether oil is cheaper than hydrogen is moot. We have only a finite amount of oil, and on the civilization timescale, it will soon be consumed. Any fuel we then use (hydrogen, methanol, or biofuels) will be synthetic and must be viewed as an energy carrier.
Fossil fuels were produced during millions of years of sedimentation and subsequent chemical decomposition of biological materials. The bulk of these materials derived from carbon dioxide absorbed by plants from the Earth’s atmosphere. History shows that we will likely burn most of these deposits in a total of 200 years. Thus, millions of years of carbon dioxide removal will be returned to the atmosphere in 200 years. What’s wrong with this picture? This state of affairs has without doubt increased the atmospheric concentration of carbon dioxide, and there is a good chance that the consequence will prove negative to civilization.
Because we are so close to the problem, some do not see the big picture. The 200 years of consumption of fossil fuels is a very narrow blip in the history of civilization. Because we are immersed in this blip, we view the burning of fossil fuels as the norm. Alas, in the large scheme of things, it is not. When the blip has passed, if civilization survives climate change, the synthesis of fuels – energy carriers – will be the new norm.
Reference A. Kimbrell, The Real Price of Gasoline, Report No. 3: “An Analysis of the Hidden External Costs Consumers Pay to Fuel their Automobiles,” International Center for Technology Assessment, Washington, DC, November 1998:
About the Author
Until 1998, Arnold R. Miller was a research professor at research universities, including the University of Illinois. In 1998, he founded Vehicle Projects Inc, which develops large prototype fuelcell vehicles such as the locomotive that is presently the largest fuelcell land vehicle. A sister organization, the nonprofit Supersonic Institute, educates the public on the benefits and challenges of supersonic transport and of hydrogen as a transportation fuel. Dr. Miller holds a PhD degree in chemistry and MS degree in applied mathematics, both from the University of Illinois, Urbana-Champaign.