by Karl Johanson
Conjecture: If Exxon owned the sun, we'd have cheap, efficient solar energy.
Conjecture 2: If the government figured out a way to tax solar energy, we'd have cheap efficient solar energy.
I have no idea of the origins of the above conjectures, but they seem to represent a widely held belief. I thought examining the plausibility that a conspiracy is taking place here might be an interesting way of looking at solar energy.
The Earth is continuously bathed in roughly 100,000,000,000,000,000 watts of solar energy. As much as say 100,000,000 thousand megawatt power plants. Surely there's plenty there for solar energy to completely usurp fossil fuels, nuclear power plants and hydro dams. The first problem with that is that much of that solar energy is already doing interesting things like growing food and forests and plankton or evaporating water to make rain and fill our lakes and hydro dams. Never the less, it seems to make sense that there should be plenty of light left over for running civilization.
The uses of solar energy (other than growing things and keeping the planet warm) can be divided into three rough categories; passive heating, active heating and solar voltaic. Passive heating is the easiest and possibly the safest of the three. Boiled down to it's essence, passive solar heating is letting the sunlight through the window to warm the place up. Active solar heating involves collecting solar heat (usually with panels and some working fluid) and either storing it or delivering it to where it's needed. Solar voltaics are devices which produce electricity when exposed to light.
The unfortunate thing about solar energy is that, while there's a great deal of it, it's diffuse and intermittent. At noon the solar flux at ground level is close enough to 1000 watts per square meter. The rest of the day the solar flux is less and at night it's close enough to zero. Solar voltaic cells have efficiencies of less than 30% and sometimes require more energy to produce then they can ever generate. Large scale solar power plants using solar reflectors to heat a working fluid to drive turbines can be more efficient then solar voltaic systems. However, a continuous capacity solar power plant (assuming 50 % spacing of heliostatic mirrors) would require fifty square miles of land. A similar power level nuclear reactor requires roughly 20 acres. Exxon doesn't need to conspire to make solar energy look inefficient, it is on its own.
I don't see that "the government" is conspiring to keep solar power down, either. When I look around at solar energy systems, most of them seem to be owned by governments. Government run space programs are continuous users of solar voltaics for satellites and space probes. Local public swimming pools have solar assisted water heating. Some new government buildings in this area have passive solar design features and some old ones now have active solar heaters. Signs away from power lines on public highways are now often illuminated by solar / battery powered lights. Contrary to the conspiracy hypothesis, governments seem to be the greatest purchaser of solar energy. Governments creating markets for solar products is part of what has brought down the costs of solar energy equipment.
Additional government support to solar energy comes in the form of some supportive laws. In California, power companies with existing power distribution lines are required to purchase power from solar (and wind) power plants at the power company's distribution cost. This means some solar (and wind) power plants can deliver power to customers at the same cost as hydro, fossil fuel or nuclear electricity because the government has saved them the substantial cost of distribution.
The safety issue rarely seems to arise during solar energy discussions. Rather than being inherently safe, as many believe, solar energy has environmental and safety concerns. The primary environmental issue of solar energy is land use as stated above. People envision the use of roof tops for most solar energy but a substantial portion of solar power systems use land where there was once nothing but plants and wildlife. Installing and maintaining roof top solar power units represents a great risk per watt. The dangers of cleaning something on a roof are not that great but the total energy per power system would be very small. The danger per roof top solar power unit times the number needed to produce say 1000 megawatts would be quite substantial. Even large scale ground based solar energy plants such as the 40 megawatt Luz plant in California have problems. This power plant heats a working fluid with mirrors to drive a heat engine. Recently the working fluid, a flammable oil known as therminol, exploded resulting in an evacuation from the area, a great deal of pollution and cause $10,000,000 damage. Another issue is that some solar voltaics are cleaned with CFCs or trichlorethane, both of which are thought to deplete the ozone layer and both of which are known to be greenhouse gasses.
As substantial portion of research into solar energy has been subsidised by governments throughout the world. This, and government tax credits for research, show governments to in general be supportive of rather than antagonistic to solar energy. Solar energy is getting cheaper and more efficient every year. Its use will continue to expand but it will not soon usurp all other forms of power generation.
Originally published by Under the Ozone Hole Number Six – November, 1993