Questions about a hydrogen economy.

Abstract

The article focuses on the outlook for a hydrogen economy. Much hope surrounds the advances in fuel cells and the possibility of a cleaner hydrogen economy. But hydrogen is not free, in either dollars or environmental damage. The hydrogen fuel cell costs nearly 100 times as much per unit of power produced as an internal-combustion engine. Hydrogen is also about five times as expensive, per unit of usable energy, as gasoline. Simple dollars are only one speed bump on the road to the hydrogen economy. Another is that supplying the energy required to make pure hydrogen may itself cause pollution. Even if that energy is from a renewable source, it may have more environmentally sound uses than the production of hydrogen. Hydrogen fuel cells have two obvious attractions. First, they produce no pollution at point of use Second, hydrogen can come from myriad sources. Pure hydrogen does not exist naturally on earth and is so highly processed that it is really more of a carrier or medium for storing and transporting energy from some original source to a machine that makes electricity. Each source, however, has an ugly side. In any case, if hydrogen were to increase suddenly in supply, fuel cells might not even be the best use for the gas. In a recent paper, Reuel Shinnar, professor of chemical engineering at the City College of New York, reviewed the alternatives for power and fuel production. Rather than the use of hydrogen as fuel, he suggested something far simpler: increased use of hydrocracking and hydrotreating. The U.S. could save three million barrels of oil a day that way, Shinnar calculated. Hydrocracking and hydrotreating both start with molecules in crude oil that are unsuitable for gasoline because they are too big and have a carbon-to-hydrogen ratio that is too heavy with carbon. The processes are expensive but still profitable, because they allow the refineries to take ingredients that are good for only low-value products and turn them into gasoline.