Can the U.S. count on trendy renewable sources of energy like wind and solar power for its energy and especially its transportation needs? Some voices in politics and media seem to think so, but the reality isn’t so clear cut.
New York Governor George Pataki recently joined a growing chorus calling for a renewable future. “Within the next 10 years,” Pataki said in his recent State of the State Address, “at least 25 percent of the electricity bought in New York will come from renewable energy resources like solar power, wind power, or fuel cells.”
And in a special “State of the Union” feature in the Atlantic Monthly magazine, Ricardo Bayon of the New America Foundation, a respected public policy institute, makes an impassioned case for moving to a hydrogen economy, claiming the need to “wean the U.S. economy—and the world economy, too—off oil. And the way to do that is to encourage the commercial development of a technology called the hydrogen fuel cell.”
Despite these assertions and predictions, the science of renewable energy tells us there are significant obstacles to realizing the dreams of these supporters.
‘We Wish This Had Turned Out Differently’
Producing electricity from solar and wind resources emits no carbon dioxide, a greenhouse gas, directly to the air. And those niche renewable sources of energy can make sense with small-scale demand in areas wealthy in wind or sunshine, and far from the conventional electrical grid, or where fossil-fuel fired power generators would deliver local pollutants.
However, in large-scale applications, such as those required to power fuel cells or to provide electricity to an entire community, solar and wind power are not only expensive, but also potentially destructive to the ecosystem.
Wind and sunshine are free, but harnessing them and generating electricity with them have significant costs. Both wind and sunlight are dilute and intermittent, making the delivery of quality electricity – available on demand – more difficult than for coal, hydro or nuclear power facilities. Solar and wind are also dilute energy sources, so they require vast swaths of real estate or surface area for collection. Given their intermittent nature, they need to be supplemented by conventional sources waiting in reserve for times when the wind doesn’t blow or the sun doesn’t shine.
The costly environmental impact and unreliability of solar and wind power have been known since the boondoggle days of solar power fever in the 1970s. But supporters pointed to the possibility that new technology would make these sources cheaper and diminish their environmental impact.
Unfortunately, new technology hasn’t helped much. Researchers at Cornell University have just restated the fact that despite engineering advances that make renewables more attractive than they were several decades ago – with higher collection efficiency of solar photovoltaic panels, or larger, more aerodynamically-efficient wind turbine blades, for example – solar and wind resources remain feeble sources of electricity.
“We wish this had turned out differently – we really do – but it’s hard to argue with the facts,” says the study’s lead author, Prof. D. Pimentel of Cornell.
California, Goodbye
Such hard engineering facts put the promise of renewable sources of energy in its proper perspective. As an example, consider whether wind could power fuel cells for transportation. The transport sector relies almost exclusively on petroleum products. Wouldn’t hydrogen fuel cells, which emit only water vapor in operation, be a good way to reduce imports of foreign oil and cut carbon dioxide emission?
Hydrogen fuel cells run off the commonest element in the universe. The sun, for instance, is 90% hydrogen in composition. The disappointment is that there are no hydrogen wells on earth – hydrogen is so light that it escapes the earth’s gravitational pull.
However, there are two hydrogen atoms in every molecule of water, and the earth’s oceans contain plenty of water.
The plan would be to use energy from wind turbines to split apart, or dissociate, the hydrogen atoms from the oxygen atoms. The hydrogen would be delivered to and placed in fuel cells that power vehicles. The output from an operating fuel cell is energy – plus water.
The first thing to note is that water moving into and out of the system means that there is a net expenditure of energy to make it work. There are other energy costs – manufacture, delivery, etc. But for the moment, let’s assume enough wind turbines can be built to make up for the energy costs of the ocean-to-wheels system.
Because no such fuel system exists in large enough scale to get a firm estimate, let’s guess roughly at the size of the smallest area that would be occupied by the wind turbines in such a situation. We’ll assume generous system efficiencies (some fuel cells can convert hydrogen into direct current at an efficiency of about 40% – that is, they are fairly efficient), and the high costs of fuel cell vehicles (estimated currently to be about $100,000) and wind power will be ignored.
Next, assume optimal wind locations are available, rich in wind resources. For now, ignore the hydrogen delivery and cell-charging losses (but remember that these losses will increase the need for still greater renewable resources).
If we assume wind turbines charging hydrogen fuel cells were able to replace the energy from about one-third of the petroleum used in transportation, that translates to approximately 10% of the total energy demand of the U.S.
To generate that amount of energy, the wind turbines would have to occupy approximately 210,000 square miles of area. That’s 25% more than the size of California (assuming all of California were suitable for wind resource siting, which it is not).
True, the turbines would be spaced apart so that the wind freely meets the blades, leaving room beyond the footprint of each wind turbine for some limited use. So in a sense, California would not be entirely turbine-towered. But it would not be wilderness, either, owing to power lines, service buildings and roads threading the landscape. Moreover, there would be blade throws, tower topplings, destroyed viewsheds and significant kills of endangered birds such as raptors.
Technology has in the past and will continue to go a long way toward solving the problems faced by society. But such enthusiasm for technology needs to be grounded in scientific reality. And wishing that wind power will soon support thriving modern economies won’t make it so.
