Researchers admit it would be decades before hydrogen power and its infrastructure are as commonplace as refineries and gas stations

What makes hydrogen an energy tool?

The most common element in the universe, hydrogen has the highest energy content per unit weight of any known fuel. Yet it never occurs by itself in nature - it always combines with other elements such as oxygen (for water) and carbon (for fossil fuels).

Once separated, hydrogen is the ultimate clean energy carrier. It can be non-polluting, is as safe as gasoline and can be produced anywhere.

NASA's space shuttles use hydrogen-powered fuel cells to operate electrical systems and the key emission, water, is consumed by the crew.

How is hydrogen produced?

It can be extracted from any substance with hydrogen: water, fossil fuels and even some organic matter.

Almost all of the 40 million tons of hydrogen used worldwide today comes from natural gas though a process called reforming. Natural gas is made to react with steam, producing hydrogen and carbon dioxide. The hydrogen is then used to make ammonia for fertilizer, in refineries to make reformulated gasoline, and in the chemical, food and metals industries. 

This is the cheapest way to make hydrogen today and is likely the way we will make hydrogen for fuel cell vehicles in the near future. Hydrogen also can be made from coal in a similar process where the coal is reacted with steam. Either way, though, the process releases carbon dioxide, a gas tied to global warming.

Carbon-free methods involve splitting water into its component parts of hydrogen (H2) and oxygen (O). 

Electrolysis uses an electric current to separate water into hydrogen and oxygen. The electric current has to itself be produced, and the easiest but least efficient way is via some fossil fuel. The holy grail of hydrogen is to use a renewable source like solar, wind, hydro, geothermal or biomass power to create the current, making the process pollution free and sustainable.

Heat or electricity from a nuclear power plant could also be used to split water, but that path still faces nuclear waste and security issues. Future possibilities include using the power of ocean waves to generate electricity and microorganisms that could be adapted to produce hydrogen.

How much water would we need if we got hydrogen that way?

Actually, not that much compared to what we already use. If we converted the current U.S. light-duty fleet (some 230 million vehicles) to fuel cell vehicles we would need about 310 billion gallons of water per year. Domestic water use is about 4.8 trillion gallons per year, and 70 trillion gallons a year are used for thermoelectric power generation. Interestingly enough, the refinery industry uses about 300 billion gallons of water a year to produce gasoline.

How do fuel cells fit in the hydrogen picture?

Fuel cells are often compared to batteries. Both convert the energy produced by a chemical reaction into usable electric power. However, the fuel cell will produce electricity as long as fuel (hydrogen) is supplied, never losing its charge.

And while hydrogen could be used to run an internal combustion engine, fuel cells are inherently 2-3 times more efficient – in the case of a car; that means they can get 2-3 times the mileage.

Like batteries, fuel cells’ performance declines over time and they have to be replaced. The goals for fuel cells are 5,000 hours of operation for transportation (representing about 150,000 miles) and 40,000 hours (about 5 years) for stationary applications. Some fuel cell technologies can match the stationary needs for 40,000 hours, but we are only about a third of the way there for vehicles, a much more demanding application.

What's holding up widescale production?

Cost is the biggest impediment. Electricity is required by many hydrogen production methods, which so far makes hydrogen more expensive than the fuels it would replace. With cars, gasoline is still easier to store than hydrogen, which needs to be compressed or kept at very cold temperatures.

In addition, an infrastructure would have to be built, and paid for, in order to produce, transport and store large quantities of hydrogen.

Wouldn't we run out of oxygen and see excess water vapor?

No. Producing hydrogen produces and consumes oxygen in the same ratio.

As for water vapor, burning gasoline already does that, though fuel cell vehicles produce about twice as much per mile. This is still a relatively small amount compared to what is already in the atmosphere naturally, and a tiny amount compared to what is being added by global warming.

How much does hydrogen cost?

Most of the hydrogen produced today is consumed on site, such as at an oil refinery, where it costs 32 cents a pound. 

When hydrogen is sold on the market, the cost of liquefying and transporting it to the user increases the price to $1-1.40 a pound.

A pound of hydrogen has a bit less energy than a half gallon of gasoline.

Is hydrogen safe and didn't it cause the Hindenburg disaster?

In general, hydrogen is neither more nor less inherently hazardous than gasoline, propane, or methane.

As for the Hindenburg, a recent study found the paint used on the blimp's skin was to blame since it contained the same component as rocket fuel. An electrical discharge ignited the skin. While the hydrogen gas used to float the blimp did ignite, it burned upward and away from the people on board and actually provided a slow, safe descent for those who stayed on board.

Don’t you lose a lot of energy when you make hydrogen?

Indeed, all energy systems lose energy (an average coal plant loses 70 percent of the energy in the coal), so we need to think very carefully about where we are going to get this energy. The sun could be the answer. Think about it for a minute and you’ll realize that we are all solar powered - the food we eat for our energy ultimatellyy comes from plants converting solar energy to carbohydrates with an efficiency of about 1 percent. Of course, by the time the food hits the table the efficiency is much lower, probably around 0.1 percent. Current commercial solar cells can convert solar energy with an efficiency of more than 15 percent.

If we take that energy and make hydrogen and then use that hydrogen in a fuel cell vehicle, the overall efficiency of sunlight to vehicle power is about 4 percent. So using hydrogen from sunlight, we can drive ourselves around with an efficiency of at least 40 times greater than we can walk.

How much is hydrogen from renewables going to cost?

With today’s technologies using electricity from wind, hydrogen would cost between 3 and 5 times that of gasoline. In Europe, where gasoline is already 3 to 5 times higher than the U.S. prices, hydrogen represents a cost-competitive fuel and with the higher efficiency of fuel cell vehicles, a strong possibility as an alternative fuel.

Can’t I put water in my tank – it’s got hydrogen in it?

Water is not an energy carrier like hydrogen and gasoline. You have to take the water and add energy to split it into hydrogen and oxygen. The hydrogen then becomes a fuel, because it now carries that energy that you added. When that hydrogen reacts with the oxygen in the air it releases that stored energy and you can use that to move the car. So if you wanted to use water as a “fuel” you would have to have two power plants in your car, one to make the hydrogen and one to run your vehicle. Better to make the hydrogen separately and just fill your car with energy.

How about putting solar cells on the roof of my car?

Our cars take a lot of energy and while there is a lot of energy in sunlight, the rooftop of your car does not have enough area. For an average car you’d need something like the size of a football field – not very practical.

*From U.S. Department of Energy Website.