by Jessi Hafer

The element
We know of hydrogen as a component of water and as one of the first elements we encounter in school. Hydrogen is the most simple atom, #1 on the periodic table of elements. One electron orbits one proton. Cosmologists speculate that the first twenty minutes of the universe was an existence of densely gathered hydrogen ions, with hydrogen atoms forming with helium atoms for the first 300,000 years. Hydrogen fusion powers the sun; today, hydrogen is about ¾ of the mass of the sun and about 90% of the volume of the sun.

The electricity
Electricity is the flow of electrons. To turn hydrogen into electricity, hydrogen gas' protons are separated from the electrons, the electrons becoming electric current and the protons passing through a proton exchange membrane to join with oxygen to release an exhaust of water and heat.

The mantra
The official enthusiasm for hydrogen of the U.S. Government seems to have provoked our own anticipation for the miracle of hydrogen energy. President George W. Bush proclaimed the importance of energy from hydrogen in his State of the Union addresses in 2003, 2005, and 2006.

2003: “A single chemical reaction between hydrogen and oxygen generates energy, which can be used to power a car—producing only water, not exhaust fumes. With a new national commitment, our scientists and engineers will overcome obstacles to taking these cars from laboratory to showroom, so that the first car driven by a child born today could be powered by hydrogen, and pollution-free.”

2005: “And my budget provides strong funding for leading-edge technology—from hydrogen-fueled cars, to clean coal, to renewable sources such as ethanol.”

2006: “We will increase our research in better batteries for hybrid and electric cars, and in pollution-free cars that run on hydrogen. “

There was no mention of hydrogen in the 2007 or 2008 State of the Union addresses.

According to the U.S. Department of Energy website, “Hydrogen is a clean energy carrier (like electricity) made from diverse domestic resources such as renewable energy (e.g. solar, wind, geothermal), nuclear energy, and fossil energy (combined with carbon capture/sequestration). Hydrogen in the long-term will simultaneously reduce dependence on foreign oil and emissions of greenhouse gases and criteria pollutants [health-harming pollutants such as ozone and particulate matter].”

The obstacles
Stepping away from the optimistic politics reveals significant scientific and technological obstacles. Energy is needed to produce and deliver hydrogen, and energy is lost when hydrogen is converted back into electricity (Bossel). Ulf Bossel estimated that only 20-25% of the total energy that must be invested into producing hydrogen can be recovered for end use in fuel cells.

Currently, over 90% of the U.S.'s hydrogen comes from natural gas, through steam methane reformation, a process that releases green house gases (Wise). Using a limited resource (with fluctuating prices) to produce “clean energy” through a polluting process doesn't make sense, though industry is working on ways to trap the resulting greenhouse gases underground. Similarly, Generation IV nuclear power plants (which won't be available for several years) may be able to reach the temperatures necessary to produce hydrogen, but with the side problems of nuclear waste and the ironic necessity of powering the power plant. A third way to produce hydrogen is electrolysis, where electricity splits water into protons, electrons, and oxygen. Oxygen is released as a gas, and electrons reunite with the protons to form hydrogen.

Hydrogen’s low density at room temperature and pressure presents a storage challenge. Hydrogen is squeezed into a denser form in three ways. Hydrogen can be liquefied near absolute zero, though the liquid contains ¼ the energy of an equivalent volume of gasoline and the chilling process uses about a third of the energy the hydrogen can deliver – this method is bulky and expensive (Wise). Through a solid-state approach, metal hydrides can trap hydrogen molecules and then release them as needed, but these materials are very heavy (with a 700 pound tank holding a few hours’ worth of fuel). Compression has been fairly successful. Though compressed hydrogen fuel cells do take up more room than gasoline tanks (for equivalent amounts of energy), fuel cell cars need fewer mechanical parts, leaving more room for the fuel cell (Wise).

A third challenge is distribution. Hydrogen pipelines can be very expensive, since the pipes have to withstand embrittlement and high pressures. Trucking and rail is inefficient and burns fuel in the process—a diesel truck would have to make 80 trips to transport enough hydrogen to fuel the cars that could be powered with one diesel truck transporting gasoline (Wise). Many hydrogen fueling stations actually make the hydrogen through electrolysis where the fuel is actually used. Some of these even use on-site wind or solar power to produce the hydrogen.

Even in those cases where hydrogen can be effectively produced, stored, and distributed, it still has very limited use and has to compete with more efficient and economical alternatives.

The successes
Hydrogen fueling stations that make hydrogen through electrolysis are one of the most efficient manifestations of hydrogen fuel, and municipal fleets are one of the most promising ways to ensure that there will be a sufficient amount of cars to make the existence of said fueling stations worthwhile. The City of Las Vegas took theory to reality when, in 2002 (note: this was before Bush's hydrogen-happy state of the union statements), the world's first hydrogen energy station was built on the City of Las Vegas' property. In 2004, the city began testing two hydrogen fuel cell vehicles from Honda, and in 2007, the city began leasing two hydrogen-fueled buses. Now, about 90% of the City of Las Vegas' fleet (over 1,000 vehicles) operate on a wide array of alternative fuels: compressed natural gas, biodiesel, reformulated gasoline, hydrogen, hydrogen enriched compressed natural gas, and hybrids.

I had the opportunity to see Las Vegas' fueling stations. One was powered by solar panels. The City Fleet Manager said that the challenges extend even beyond technology—zoning and permitting the fueling stations was a politically sensitive issue, with some worried about explosions. Even though their stations are already outdated (“You wouldn't build a station like this today,” the fleet manager explained), they have been visited by government, business, and industry leaders from all over the world.

Perhaps the best lesson that can be learned from Las Vegas, though, is not that hydrogen fuel can work. Perhaps the greatest lessons are those of diversified fuel sources, willingness to try out new approaches, and the value of good examples.

The “alternatives”
Why waste time on hydrogen when we could be mining the moon for helium? While I am somewhat kidding, there are those who do not joke about this. They say that fusion reactors using helium-3 from the moon could generate huge amounts of energy. I saw a former astronaut give a talk about this in 2002, and I thought he was kidding at first. Don't get me started on the amount of energy it would take to get a bunch of mining equipment to the moon...

Hydrogen energy does make more sense than mining the moon for helium, at least.
*****
References:
•Bossel, Ulf (October 2006). “Does a Hydrogen Economy Make Sense?” Institute of Electrical and Electronics Engineers
Proceedings.
•Wise, Jeff (November 2006). “The Truth About Hydrogen.” Popular Mechanics.