Several readers have pointed out that my recent column about the relative safety of nuclear power did not consider either solar or wind power.
Solar and wind energy are indeed safer than energy generated from fossil fuels, nuclear reactors or hydroelectric dams. But neither solar nor wind systems appear to be capable of generating the massive amounts of electricity that are needed to power cities and factories.
For that kind of base-load power you need fossil-fueled, nuclear or hydroelectric systems.
Yes, solar and wind energy are virtually free and nonpolluting. The problem with them is that they are too thinly spread out, too low-level to be useful for concentrated, base-load power generation.
And they are not all that reliable, either. The winds blow fitfully. Sunshine is interrupted by clouds and nightfall.
Still, it might be possible to use wind and solar energy to move away from centralized systems, in which electricity is generated by utility companies’ power plants and distributed through wires to users.
A growing number of houses are going “off the grid.” Instead of buying electricity from the region’s utility companies, these homes generate their own electricity, using sunshine and windmills.
How far could this trend go? Could most of the homes in the U.S. coat their roofs with solar cells and erect windmills? Could condo buildings, airports, factories go “off the grid” and generate their own electricity?
That could happen, if and when the cost of photovoltaic cells comes down a bit more and the complaints about the noise and hazards (to birds, mainly) of windmills are overridden.
However, as physicist Axel Kleidon of the Max Plank Institute for Biogeochemistry, in Germany, points out, there are limits to how much energy we can extract from wind and solar power.
Humankind currently uses roughly 74 terawatts (trillions of watts). Of this, about 17 TW comes from burning fossil fuels. Kleidon says that if we build enough wind farms to significantly decrease our use of fossil fuels, we might use so much of the planet’s wind energy that we could seriously change today’s climate patterns.
According to his calculations, the more wind energy we use to generate electricity, the more we will change patterns of precipitation, atmospheric turbulence and even the amount of sunlight reaching the Earth’s surface — because we will be altering the amount of global cloud cover.
Even solar cells present a problem, because they convert only a small fraction of the sunlight they receive into electricity. The rest becomes waste heat, which contributes to climate-changing global warming.
In other words, if we convert to solar and wind energy on the massive scale necessary to put a major dent in our use of fossil fuels, we might be creating environmental problems that are just as bad as the pollution and warming effects of the fossils fuels.
As the old saying goes, there ain’t no such thing as a free lunch. Every energy option we choose has its drawbacks.
However, there is a way to utilize solar energy that can provide massive amounts of electrical power without significant environmental effects: Put the solar cells in space.
The concept of solar power satellites was invented by Peter Glaser in 1968. The basic idea is simple: build huge satellites in high orbits, where they are always in sunlight.
The satellites are covered with photovoltaic cells that convert sunlight into electricity. The electricity is beamed to Earth as microwaves and converted back into gigawatts of electricity.
A half-dozen such powersats could produce as much electricity as all the power plants in the United States. While they would be expensive to build, their operating costs would be close to zero and their environmental effects would be negligible.
We know how to make solar cells and microwave transmitters. We know how to build structures in orbit. There are no major technological problems to be overcome.
The problems facing solar-power satellites are political and financial. Raising the billions of dollars needed to build the first one depends mainly on raising the confidence in the minds of potential investors.
If you want a truly safe way to generate enormous amounts of electrical energy, solar-power satellites are the way to go.
Bova’s technothriller, “Powersat,” tells how the first solar-power satellite could be built. Bova’s website address is www.benbova.com.