Hydrogen: Adieu to the Carbon Age

The fact that a hydrogen economy is inevitably on its way can seem implausible today. We live at the peak of the oil age. Exxon, Mobil, BP, Shell, Texaco and other oil and gas multinationals regularly appear near the top of the Fortune’s Global 500. As captains of a successful industry, former oil industry executives also hold prominent political positions around the world.

Oil revenues are so steep because world oil use is at a record high — with some 3.5 billion tons consumed in 1999. The rise and fall of oil prices, OPEC decisions and debates over oil exploration in ecologically sensitive regions often grab headlines.

Yet, the reality of an eventual transition to hydrogen becomes more evident — if and when one looks at history. Since the mid-19th century, the world has seen a slow shift in its energy sources — from solids to liquids to gases.

Until the middle of the 19th century, reliance on wood for energy was common in most parts of the world. But in Great Britain, where population density and energy use were growing rapidly, coal began to supplant wood.

As it turns out, coal was as abundant as wood — but more concentrated. It had the added benefit of being less bulky or awkward to transport.

Coal remained king of the energy world well into the 20th century. But by 1900, the advantages of an energy system based on fluids, rather than solids, began to emerge.

As transportation shifted away from railroads and toward automobiles, it created problems for coal — and generated opportunities for oil. The liquid fuel possessed a higher energy density, and it also flowed easily through pipelines and into tanks. By the middle of the 20th century, oil had become the world’s leading energy source.

But dominant as oil has become, it now faces an up-and-coming challenger in natural gas. Not only is natural gas cleaner and lighter than oil, but it burns more efficiently. It also can be distributed through a less conspicuous, more efficient and more extensive network.

Natural gas is now the fastest-growing fossil fuel, and the fuel of choice for electricity. It has also become the second-leading global energy source — finally overtaking coal in 1999.

This highly visible economic shift from solid to liquid to gas as fuel highlights a less visible scientific process — “decarbonization.” As one moves from wood to coal to oil to natural gas, the ratio of hydrogen (H) to carbon (C) in the molecule of each successive fuel source increases.

Jesse Ausubel of Rockefeller University argues that “the most important, surprising and happy fact to emerge from energy studies is that for the last 200 years, the world has progressively favored hydrogen atoms over carbon. The trend toward ‘decarbonization’ is at the heart of understanding the evolution of the energy system.”

The next logical fuel in this progression is hydrogen. It is the lightest and most abundant element in the universe — and the power source of our own sun. It is found on Earth in water, life forms, and hydrocarbon fuels.

Its uses for fuel are also abundant — and growing. Hydrogen is already established in space programs and industrial applications, thanks to ongoing improvements in fuel cell technology.

At first, it seems likely that hydrogen distribution will initially build on the existing natural gas network. Hydrogen will derive at first from natural gas — and be used to run high-efficiency fuel cells.

Eventually, hydrogen will likely create its own full-fledged network, with supplies generated by splitting water into hydrogen and oxygen. This will be accomplished via electricity obtained from solar, wind and other forms of renewable energy.

The result will be cleaner energy, of course. But the production of hydrogen from virtually limitless stores of renewable sources also will free the energy system from its present inefficient slavery to carbon.