One of the greatest challenges facing humanity is meeting the ever-growing global energy demand in an environmentally sustainable and responsible manner. Sunlight, also known as solar energy, is a clean, abundant, safe, and free resource that provides approximately 1,000 watts per square meter of power to the Earth’s surface on sunny days. The amount of solar energy that hits Earth within two hours is enough to supply the entire world’s energy needs for one year.
How do we capture, store and convert this incredible natural resource most efficiently? First, sunlight is made up of many wavelengths. The lower energy infrared radiation, which we can’t see but feel as heat, makes up about half of the sunlight. The remainder is visible light and ultraviolet light, which are higher-energy. While some technologies that harness solar energy use the whole spectrum of wavelengths, others only use a fraction.
Photovoltaics are also known as solar cells. They convert sunlight into electricity. Photo: (c) Elena Elisseeva/DepositPhotosOne of the first technologies that come to mind when discussing solar energy is the growing use of solar cells, also known as photovoltaics, which converts sunlight directly into electricity. The silent, long-lasting and non-polluting solar cells convert between 10 and 15 percent of the energy received into usable energy.
These aren’t the only ways to generate electricity from solar energy. You can also focus sunlight on a very small area using a series of lenses or mirrors to heat water and make steam. To generate electricity, high-pressure steam can be driven by a turbine.
We can store electricity produced by steam-driven turbines or solar cells by using batteries. This allows us to release electricity when it is dark or cloudy.
There are two ways to store solar power for later use. The first is to store the thermal energy from concentrated sunlight in the heat capacity of molten salt. This is the liquid form of anionic compounds like sodium chloride at high temperatures. To generate electricity, later on, heat is transferred from the salt to water using a heat exchanger.
Another way to harness and store solar energy is to use sunlight to make fuel. Photoelectrochemical cells, for example, use solar energy to convert water into hydrogen and oxygen gases, which can then be stored as fuels. The gases are then recombined in order to produce electricity, a device called a fuel cell. This approach has the attractive characteristic of generating electricity from water as a byproduct.
It is important to remember that sunlight can also heat water outside of your home. This can be used to wash or shower, which is quite common in the developing world.
Although many of these technologies are currently in use on a limited scale, we need to continue to innovate ways to store solar energy and encourage sustainable energy policies that will benefit future generations.
This post was written by Daniel Massaad, owner and expert solar technician at Energy Solutions Direct! ESD is the top choice for Tampa Bay Solar! Our licensed and certified contractors are masters of their craft; with years of experience servicing the great Tampa Bay area and beyond, the choice is simple. ESD excels at offering you the best in solar value!