What are the advantages and disadvantages of hydrogen energy?

It’s not an exaggeration to say that we are facing a global energy crisis. Our dependence on finite energy sources like oil, coal, and natural gas is coming to an end. With oil reserves expected to deplete in just a few decades, the rush is on to find sustainable alternatives that will power our cars, homes, and businesses without harming the environment [source: The Independent].

One promising solution for our energy needs is hydrogen — an endlessly renewable and relatively clean fuel that is seen by both scientists and policymakers as a viable substitute for fossil fuels. The potential of hydrogen power is so compelling that the Bush administration committed $1.2 billion for research and development in 2003 [source: U.S. Department of Energy].

Does hydrogen fuel cell technology live up to its promise of providing a clean and efficient energy source? It all depends on how hydrogen is produced. While hydrogen is abundant in natural sources like water and natural gas, and it’s much kinder to the environment than fossil fuels, it's essentially pollution-free. A hydrogen fuel cell in a vehicle produces no emissions; it only emits water vapor and heat. As long as renewable energy sources like solar or water are used in the production process, hydrogen fuel cells don’t pollute. Additionally, hydrogen fuel is roughly three times more efficient than gasoline [source: US News].

However, hydrogen isn't always produced cleanly. Extracting hydrogen from water is costly. Although non-renewable sources like oil and natural gas are cheaper, using them continues to deplete our fossil fuel reserves. The carbon dioxide released when hydrogen is extracted from fossil fuels offsets any environmental gains. Experts warn that hydrogen leakage during production could further damage the ozone layer and accelerate global warming [source: PBS]. There are other challenges: Scientists are still working on how to store hydrogen. Since hydrogen has low energy density, it must be stored and transported under high pressure, making it cumbersome and impractical. The pressure issue is compounded by hydrogen’s high flammability—though unlike gasoline, hydrogen lacks a distinct odor. Detecting leaks before combustion requires special sensors. Another issue is the need for a network of refueling stations to accommodate hydrogen-powered vehicles across the nation. Will fuel producers build a hydrogen station on every corner?

Still unclear about hydrogen and hydrogen fuel cell technology? The next page covers all the essentials.

Hydrogen Energy Facts

Hydrogen is the simplest and most abundant element on Earth. Represented as "H" on the periodic table, it is a gas that combines with oxygen to create water (H₂O) and with carbon to form substances like methane and coal.

Hydrogen is an incredibly clean energy source, offering the highest energy content of any fuel currently in use. Although hydrogen isn't found naturally on Earth, it can be produced. Utilizing hydrogen energy has minimal environmental impact since it only releases water and heat as byproducts. However, the production process for hydrogen can have some environmental drawbacks.

Hydrogen production requires separating it from substances like water, biomass (such as plant and animal waste), coal, or natural gas. Today, approximately 95% of hydrogen is made through steam reforming, a method that separates hydrogen atoms from carbon atoms in methane. Unfortunately, this method emits greenhouse gases that contribute to global warming.

The alternative method, electrolysis, involves extracting hydrogen from water. Powered by renewable energy sources such as wind, solar, and hydropower, electrolysis produces no emissions. However, the process is costly, and scientists need to find a way to produce hydrogen more affordably from clean, renewable sources to unlock its full potential as an energy source.

In the U.S., approximately 9 million metric tons (9 billion kilograms) of hydrogen are produced annually, enough to fuel 30 million cars. Much of this hydrogen is used in refining, metal treatment, and food processing. Additionally, NASA utilizes hydrogen as fuel in its space missions.

The crucial element for using hydrogen as a power source is the hydrogen fuel cell. This device converts hydrogen energy into electricity. Fuel cells can power vehicles and even provide electricity to remote areas without power lines. In cars, the electricity produced from hydrogen powers the battery, functioning similarly to today's hybrid electric vehicles.

Flip to the next page for a wealth of information on renewable energy sources.