By Ivan Anic
About 4.57 billion years ago a molecular hydrogen cloud collapsed leading to a formation of a new star, our star, the Sun. This celestial body is responsible for the emergence of life on our planet, giving it energy through nuclear fusion. The sun is the reason that we have not only life on this planet, but it's also the reason the planet exists at all. It is not surprising that the Sun's energy potential is boundless. Our technology is only now trying to understand how we can collect its energy to our maximum benefit, which plants have so spontaneously done for billions of years. Though throughout man's history, Solar power has been used since the inception, we have only now began to explore how we can use it to generate electricity, a tool that our modern civilization can not do without.
Two general ways of harnessing solar energy can be classified as active and passive, depending on the ways the energy is captured, converted and stored. Passive harnessing mainly refers to the design of a structure and the materials used to build it, in such cases as a building. For example, in such a building the airflow could be used as a type of air conditioning system; the position of the Sun in contrast to the building can be used to block sunrays or create shade; insulating materials, which are materials that can store heat can help control the buildings temperature etc. In the video segment Lauri Walker explains that insulation in an average home can do miracles for the electric bill.
However, if we want to take Sun's energy and convert it into electrical current we need to use so called active methods collecting the Sun's energy. It is what we see in the solar panels, and solar-thermal power plants, which are electricity generators. There are two relatively easy and affordable methods of doing exactly that:
1) Thermal: This type of energy is a relatively simple to utilize, and has been employed for thousands of years. New inventions, such as the electric generator allowed us to be more efficient in harnessing thermal energy to create electricity. We accomplished this by using concave mirrors to point Sun rays to a specific point. In doing this we concentrated the heat in a particular area and temperature raised significantly. We then used this concentrated, or extreme temperature to heat up a medium such as gas or liquid. The medium, in the form of a vapor, is then used to run the turbines of the electrical generator. In the process the medium is cooled and then recycled. It is a simple approach to creating electricity, however it has limitations – Thermal energy is dependent on the weather and time of day.
2) Photovoltaic: This type of energy uses light to create electricity. This method uses photons, elementary particles of light, to knock electrons into higher state of energy. This creates an electric current. Production of electricity for photovoltaic cells has been doubling every 2 years, making it the world’s fastest growing technology. In 2008 the photovoltaic production increased by 110%. Although this method has been rapidly growing, it does have its limitations. Similarly to Solar-thermal generation, the production is tied to the time of day, and is unproductive at nightfall. However, there is research on the way to not only make the PV cells more efficient, but also to generate energy at night.
One way to address the lack of energy production when the Sun is not available is the use of a system called the smart grid. This is a computer operated electric grid that automatically delivers needed energy to meet the needs of a building or an area. It can work in conjunction with an energy source such as a solar panel by generating energy with the Solar panel when energy production is low. The smart grid uses energy from other sources to deliver it to the location, i.e. wind turbine farm, or any other energy source connected to the grid. The challenge of this system is that it requires building a new infrastructure, which could gradually be introduced into the already existing system.
Adoption of the solar systems in the existing grid is already happening in Southern California. Walter Ellard from SouthCoast Energy mentions Southern California Edison, an energy company that records kilowatt hours produced by the home into an "energy bank." During the night the energy would be pulled from the grid and the kWh collected during the day would be used as credits. So what would happen to kWh of energy unused by a household? In California Gov. Arnold Schwartzenegger passed an act AB 920 or the California Solar Surplus Act of 2009. This act allows solar energy producers, such as homes to be paid at competitive rates for their electricity by the regional energy provider.
When asked which building he would convert into solar powered Walter Ellard, President of SCE and an electrician, proposed a curios idea, installing solar panels on all federal buildings since "they are the biggest users of energy." Walter is confident that budget deficit would start shrinking, which we need urgently in California. Who knows maybe Arnold reads this.
Solar energy production as it currently exists is not perfect. Along with technological limitations, we also encounter the issues of an available and trained workforce. There are many organizations that convert our energy grid into Solar, and I highly recommend researching these exciting approaches further.