The power of the sun has been harnessed for centuries, dating back to the legend of how the famous Greek mathematician Archimedes focused the suns rays on polished shields to drive off the encroaching Roman fleet.
In everyday life, we’re familiar with the power of the sun. The most common solar-powered device found in almost every household is the solar powered calculator – a device that seems to last forever with just a little light to help it out.
Solar power is literally the process of harvesting the sun’s rays and transforming them into energy called photovoltaics. However, this process has been fairly expensive in the past and has been the primary barrier for why this process is not used more frequently in total worldwide energy production.
An Untapped Reserve of Renewable Energy
Solar power is one of the most abundant renewable resources in the world, but we’ve only just begun to tap the surface of this powerful energy source. Last year, less than .02% of the world’s energy came from solar power and only 2% of the world’s energy came from renewable resources at all 1!
But the trend is catching on, as the energy crisis and pollution issues continue to escalate. Just last year, two of the largest solar power plants were built – the 40 MW Waldpolenz Solar Park in Germany and the 46 MW Moura photovoltaic power station in Portugal.
Unfortunately, the United States has been slow to catch on to this trend, although significant research has determined that the southwestern deserts of the US could produce enough energy to power the entire country with absolutely no pollution!
Currently, the United States primarily consumes petroleum, natural gas, and coal – fuels that have extremely negative effects on the environment including greenhouse gasses and pollutants that cause acid rain.
The United States is responsible for more than 21% of the emission of energy-related carbon dioxide, which is the main cause of the greenhouse effect.
How Solar Energy Is Harvested
Harvesting solar energy has seen years of experimental systems. The most popular type of system is the parabolic trough, which uses trough shaped mirrors to concentrate the sun’s rays on a receiver that heats thermal fluids to produce a type of super steam, which in turn produces energy. The first large-scale parabolic trough was built in the mid 1980s in the California Mojave Desert. See an example below.
Another type of solar thermal collector is the parabolic dish, which is used to focus sunlight on a receiver located near the center of the dish. That beam of energy is used to heat a fluid, which in turn generates electricity.
The solar updraft tower works like a large greenhouse where, when the air is heated, it expands and pushes the air into a central converter where it is turned into electricity.
The Solution for an Intermittent Energy Source
While these three technologies have been proven extremely successful, there is one obvious issue with harvesting solar power – the sun goes down at night.
Another issue with solar energy is that it is more abundant in hotter climates as well as during the hotter times of the year. For an example, take a look at the chart to the right, which displays solar energy production throughout the year at AT&T Park in San Francisco, California. As you can see, energy production was at its peak in the months of April, May, and June, while the lowest months were in December and January.
Because of the nature of solar energy as an intermittent energy source, something had to be done to supplement the times when it was not available.
A pilot project of the University of Kassel in Germany called the Combined Power Plant, combined solar energy use with other renewable resources and proved that solar energy can be used in combination with these other renewable resources to provide a reliable source of energy.
The Combined Power Plant links and controls 36 wind, solar, biomass, and hydropower installations throughout Germany. It was proven just as reliable as modern power plants and used 100 percent renewable resource with zero pollution!
Solar energy can also be stored.Three methods of solar storage are used today. The first and most efficient is made possible by molten salts, which is a liquid at atmosphere pressure, and can store energy at high temperatures. The second method is pumped-storage hydroelectricity, which stores the energy in the form of pumped water when there is surplus electricity available. As far as smaller residential systems go, if the system is off-grid, the energy is stored in rechargeable batteries. If the system is connected to the grid, excess power is fed into the grid and the owner benefits from earning credits from the power they supply to the grid, and, at the end of the year, the power company will pay for whatever excess power was used during that time.
The Economics of Solar Power
It’s true that, in the past, solar technology was extremely expensive and primitive at best, but recent technology has made significant improvements in harnessing this valuable resource. According to a recent article in Science Daily, the cost of installing these systems has decreased significantly over the last several years, especially in the residential market 7, causing an increase in the number of solar power systems installed today.
This increase in solar energy systems in the residential market is also due to government incentives, which provide tax rebates for anyone who installs a solar energy system on their home and from the availability of green financing.
The number of solar energy systems installed in 2007 increased more than 46% and the number is steadily climbing. Take a drive through your local neighborhood and there’s a good chance you’ll find solar panels on at least one of the houses. While solar power units can be a hefty investment for the average homeowner, new technology is driving the costs down and giving clean energy a chance.
There’s even a recent move toward companies leasing solar panels to homeowners for a fraction of the cost! An average solar power system can cost upwards of $30,000 but these new companies are offering to install and maintain a solar power system for less then $1,000!
By taking advantage of this powerful renewable resource, we can create an unlimited source of energy that once solar plants have been established, can be a cost-effective and pollution-free way to harvest energy and limit our use of fossil fuels such as coal and petroleum.