May 2005 –

On Hydrogen and Its Net Energy Value,
Even the Short Answer is a Long Story

On a recent morning business program on CNBC, they were lamenting the high price of petroleum. An investment guru declared, "Hydrogen is ultimately the answer. It's cheap, and it's available!" (More on this in a moment.)

"So we'll all be driving around in mini-Hindenburgs?" asked the program's host. (More on this now: The doomed dirigible is widely believed to have burned because of a flammable coating on it interior walls, not because of the hydrogen gas inside.)

"And doesn't it take as much energy," the host continued, "to make hydrogen as you get out of it?"

The second question is the interesting one, and is key to some big decisions we will face about transportation and energy in this country. The short answer is yes. Not only does it take as much energy to produce hydrogen as the fuel will contain. It takes more. Using today's most efficient methods and feedstock, the production process consumes about 1.4 times as much energy as what we get from the fuel. Put another way, the return on energy invested is about 70 percent.

Is that an indictment in itself? Absolutely not. Think of it this way: Suppose you could transform a cheap, abundant, and less useful energy source (say, chicken droppings) into a clean, valuable, and more useful form of energy (like hydrogen, assuming we all drive hydrogen fuel cell cars).  Do that, and you've done a good thing. No one would squawk about your NEV (that's net energy value--the output energy as a proportion of the input) being below 100 percent. No one would say the chicken droppings were wasted.

And that, folks, is the short answer. It's not about total energy. It's about useful energy.  Now for the whole story, which is far more complicated, ambiguous, and interesting, read on.
 

Stiff Competition

Again, 70 percent efficiency comes from the most today's best methods and materials. Sadly, chicken droppings aren't part of the process, which involves subjecting natural gas to high pressure and steam, and then separating and segregating the hydrogen. Natural gas is a prized energy resource itself, of course. And making the steam requires a substantial input of fossil fuel energy to heat water as high as 1,000 degrees Centigrade.

How does a 70 percent return stack up against other fuels? Gasoline and diesel are the big dogs in this contest. In extensive searching, unfortunately, I haven't found a satisfying across-the-board NEV figure for gasoline. (If someone can help, please do.) My difficulty, I think, reflects the fact that NEV calculations aren't exactly standardized. Certainly we must account for the direct expenditures of energy in drilling 6,000-foot holes in the ground, pumping crude and shipping it across the ocean, and operating refineries. Do we also account for energy expended in making the steel that goes into drill bits and tanker ships?

How to precisely calculate NEV becomes a somewhat political matter, and for some fuels (see ethanol, below) it is has been subject to political manipulation. Still, petroleum fuels clearly are king. Their NEV is rarely cited perhaps because their economics are beyond question. Petroleum's big advantage is its high energy density, roughly three times that of hydrogen per liquid gallon.

Ethanol has been kicked around a lot in this arena. A March 2005 study, Ted Patzek, an engineering professor at the University of California, Berkeley, said using ethanol as motor fuel results in a 65 percent net loss of energy.  Similar studies by David Pimantel (some with Patzek) reached similar conclusions. What make ethanol production economic, say the critics, are misguided government subsidies for growing corn and producing ethanol as fuel.

The other side says such studies are bunk, based on outdated assumptions about the efficiency of production machinery and other bad data. They say feedstocks can include less costly forms of biomass, such as wild grasses. They point to a study in 2002 by USDA, which put the net energy value of corn ethanol at a positive 134 percent. Significantly, that study also said liquid fuels such as gasoline and diesel (generally the most valuable energy sources) make up only a small part of the energy input in ethanol production. Much of the rest is coal, making electricity to run ethanol production plants. Ethanol enthusiasts (supported by corn growers) say the fuel's net energy value is better than 175 percent under certain conditions.

Having heard such widely divergent claims for years, I am unable to draw clear conclusions about the net energy value of ethanol. What is clear is that good alternative fuels are exceedingly hard to find, and all will have a tough time competing with petroleum. To me it seems the NEV issue is sufficiently complicated to justify giving ethanol the benefit of the doubt. It is a relatively clean-burning, domestically produced liquid fuel which, in a gasoline vehicle with only minor modifications, can replace up to 85 percent of the fuel in the tank. Ethanol production in the U.S. has expanded steadily for two decades to 3.41 billion gallons annually. The advantages are too significant to dismiss, I say. Continue the subsidies and support ongoing research of new feedstocks.


Does Hydrogen Add Up?

Clearly, we are using up valuable forms of energy to produce hydrogen (which is technically an energy carrier, not a first-level energy source, but for this discussion, no matter). We get less energy out it than what we're putting in. But we are not losing any sleep over it. Why? Obviously, because hydrogen is not the lifeblood of our transportation system. It is a marginally important product used in making fertilizer and refining petroleum.

The grand vision of many is a world built on a "hydrogen economy." Most forms of energy production and consumption would change dramatically. Affected would be not only the fueling of cars, but the heating of homes, the production of electricity, and the way business and industry operate.

A part of this vision is to use water, not natural gas, as a feedstock from which to produce fuel.  Water contains hydrogen, molecularly bound up with oxygen.  Hydrogen is also the most abundant element in the universe, for what that's worth.  But when the CNBC guru said hydrogen is "available" and "cheap," he was really doing what gurus do best--looking forward.  He might as well have said hydrogen is "everywhere" and "free."

Critics say using water unfortunately would increase, not reduce, our use of fossil fuels. Why? Because getting hydrogen out of water is much tougher than getting it from natural gas. The process entails running an electric current through water to separate its hydrogen from its oxygen. Assuming the electricity comes from conventional sources (power plants fired by gas or coal), this process is only 20 percent efficient overall. You get one part energy out for every five parts you put in. The savings in natural gas as a feedstock is more than erased by greater consumption of gas or coal or something else valuable used to generate electricity.

Forget conventional sources, the visionaries reply. Tomorrow's electricity can come from renewable sources such as wind and solar. This is a nice idea. Harvest clean energy from the sun and the wind and use it to create a clean transportation fuel. The system is sustainable in a virtuous loop, with benefits that go beyond the conservation of fossil fuels. With less burning of gas and coal, the air will be cleaner and people will be healthier. In the evenings, we will drive our emission-free cars out to the wind farms to watch the sunset.

Here again, reality rears its unwelcome head. No form of renewable production is cost-competitive with conventional sources (gas and coal) as a means to generate electricity. Wind is getting closer. Photovoltaic solar energy still costs around 20 cents per kilowatt-hour, compared to about 8 cents (national average) for conventional electric power. That may all change. Technological progress may accelerate. Pigs may fly. But the question will not be, "How much hydrogen can we create with renewable energy?" The question will be, "What is the best use of all the precious energy that we generate, including the small portion that comes from renewable sources?"

Renewable energy will not be "free" as some advocates may envision it. For a long time, maybe forever, it is likely to be the most costly component of all the energy going into the grid. It is amusing to see hydrogen now winning friends among the forces behind a revival of nuclear energy. Typically that crowd doesn't sit in the same pews as the tree huggers. But new nuclear reactors could be very well equipped for hydrogen production.


Wattage For Your Cottage

As if the issues weren't entangled enough, along comes the idea of cars as rolling utilities. If automobiles can generate their own electricity, why have so many stationary power plants? The 26 million registered vehicles in California, if fitted with electric generators connected to the grid, could produce enough power to replace more than 500 average size power plants. This vehicle to grid (V2G) concept has much appeal. Cars could supply power during daytime peak hours, when many them are standing still at office buildings. When necessary, they could even draw power from the grid, notably at off-peak hours.

A related idea is to interconnect your car and your home.  When you've got your own mobile power plant, why buy electricity from the grid?  Make your own.  This idea and the V2G concept are relevant to all kinds of electrically driven cars including gas-electric hybrids. They represent one more good reason, in the eyes hydrogen fans, to move toward a transportation system emphasizing cars driven by electricity.

Other wrinkles should be acknowledged: Fuel cell cars, say their proponents, would be twice as efficient as today's gasoline cars, in terms of energy-in, energy out. Factor that in, when you're considering whether hydrogen is a fuel for which we'd pay up. But also think of the purchase price of the vehicles, using a technology that is still many miles away from commercial reality. That alone is a potential deal breaker, as is the cost of building a nationwide hydrogen fueling infrastructure, which has been estimated at $500 billion.

By comparison, the war in Iraq almost looks cheap. And that comparison is apt. Accounting for the cost of a "hydrogen economy" may require 13 figures (as in $1 trillion). But what is the cost of doing nothing? Support of the petroleum economy arguably engenders inevitable war, lost lives, anti-Americanism around the world. Of the wildly favorable NEV and energy density figures that define gasoline, what is the price? More days like September 11? More years in Iraq?

Back to the original question: Does it make sense for us to stake our future on a fuel (like hydrogen) that is likely to consume more energy that it yields per unit volume? Well, certainly not to the exclusion of other transportation alternatives such as petroleum-electric hybrids, plug-in hybrids, natural gas vehicles, residential refueling with natural gas, biodiesel, ethanol, and flexible fuel vehicles that can run on ethanol or gasoline. That's the easy part of the answer--diversify the portfolio.

I say hydrogen is in no way disqualified as a future energy source by its low net energy value. In part that's because it can be created with water, which is abundant, and electricity. Granted, the process efficiency is poor at present, and today's electricity comes from fossil fuels. But hydrogen can create opportunities to exploit energy sources that otherwise might not stand well on their own. It can help integrate and unite seemingly disconnected sources such as wind, solar, coal, oil, gas, and nuclear. Hydrogen is a potentially significant stretcher of supply, with a legitimate role in the high-risk, high-reward section of our energy portfolio.
 

For three years, I was the editor of Alternative Fuel News, published by the U.S. Department of Energy.  Write to me at  tom@larocque.biz