Solar Power -- The Endless Energy Source
For decades solar technology was only available in the form of silicon wafer cells. The high production costs of these fragile wafer cells, coupled with poor cost/efficiency ratios, made solar energy impractical for most energy applications. For these reasons, solar power was considered a niche technology.
Climate change impacts and the rising costs of fossil fuels has changed the economic equation surrounding solar energy, and as the technologies involved became more efficient and reliable, solar energy began to demonstrate its full potential, blossoming into a market full of intriguing designs and applications. The technology now has diversified into products that provide heat, electricity and substitutes for batteries.
The bulky, inefficient solar wafers have been replaced by thin films of photovoltaic (PV) cells. These cells - 100 times thinner than wafers, generate energy more efficiently and are easily applied to an energy conductive substrate. The international solar company Nanosolar has developed a photovoltaic ‘ink’ that can be used to easily apply a thin layer solar cells to a substrate.
To see how Klean Industries is developing nanocarbon materials for use in various industries please click here.
The simple explanation of how PV cells work is:
- Photons (essentially light particles) hit the solar panel and are absorbed by the semiconducting materials, such as silicon.
- The reaction of the sunlight with the semi-conductor knocks electrons (which carry a net negative charge) free which flow through the material to produce electricity.
- The positive charge, offset by the removal of the electron flows in the opposite direction.
The new size and efficiency of solar technology has made possible solar applications employing micro-unit collectors ranging from water pumps to solar powered trash receptacles and remote signal stations and lighthouses. Solar powered automobiles are moving closer to reality as well.
On the micro level, solar technology is proving beneficial to millions living in villages around the world – often in sun scorched regions – that lack access to electricity.
For example, India faces enormous problems in supplying electricity to its rural areas where many of its 1.3 billion citizens live. With an average of 300 sunny days per year, India is looking to solar technology to bring power to its more remote villages. Solar cookers, which last up to 20 years, have been a staple in India since 1982. Over 75,000 units are produced in the country each year. Since 2001, many Indian states have supplied villages with solar powered lighting and water pumps and small solar hubs to generate power for school computers.
These small scale applications show the versatility of solar power in providing better access to basic necessities such as lighting, water, cooking and education.
In developed countries the use solar thermal technology for home water heating is the most common application of micro-unit collectors. For an installation cost of $5,500 on average, placing solar thermal panels on the roof of a house can save consumers between 50% to 80% on utility payments each year, paying back the cost in 4 to 8 years depending on location.
Solar thermal is becoming the water heating option of the future. Instead of providing electricity, the cells are designed to convert photons to heat. Canada, China, Australia and the United States are among the lead countries rolling-out major programs to switch traditional water heating to solar thermal heating.
Australia has initiated the Solar Cities Programme (SCP), a $75-million initiative involving the use solar power, energy conservation practices and improvements to energy pricing to reflect the true costs of energy provision. The SCP is designed to provide a sustainable energy future in urban locations throughout Australia. Its four solar cities, Adelaide, Townsville, Blacktown and Alice Springs have reduced their combined greenhouse gas emissions by 76,000 tonnes each year and have saved over 65,000 kWh of electricity.
Ontario has launched a $150-million plan to retrofit Ontario homes to be more energy efficient. The project, introduced earlier in 2007 by Ontario Premier Dalton McGuinty, will provide Ontario homeowners up to $5,000 for energy retrofits which includes the installation of solar domestic water heating.
British Columbia has launched a 100,000 Roofs program. The goal of the program is to add solar thermal panels to 100,000 homes for water heating. The B.C. project was launched by the non-profit British Columbia Sustainable Energy Association (BCSEA), an organization promoting the advancement of sustainable energy technologies in British Columbia.
GRID Connected Solar
The application of solar technology has moved far beyond micro-unit collectors, advancing to macro-unit projects that are grid connected. These large scale projects utilize both solar thermal and solar electric technology and are best suited (but not limited) to desert regions which receive large amounts of sunlight year round
Solar thermal power plants use heat to generate steam which powers an electricity generating turbine. Excess heat is stored in a material with high energy density, such as graphite, for use during overcast days or night. Solar electric technology costs more to manufacture, but its connectivity directly to the grid simplifies the conversion of sunlight to energy. Excess energy from electric collectors is stored in solar batteries.
The choice for solar thermal versus solar electric depends on the location. In areas of high daily average temperatures, solar thermal is the best option. In areas with adequate sunlight, but moderate or low daily average temperatures, solar electric is more practical.
The Mojave Desert in Southern California contains the largest solar power plant in the world. The power plant utilizes solar thermal energy and generates 350 megawatts (MW) capacity of electricity. The power plant takes up 1000 acres and each of the 400,000 solar mirrors can generate up to 400 degrees Celsius of heat.
The world’s largest solar electric plant will be built in Victoria, Australia by 2013. The $420-million plant will operate at a 154 MW capacity; will provide clean electricity to 450,000 homes; and will reduce greenhouse gas emissions by 400,000 tonnes per year. The power plant will also utilize a tracking system which allows solar arrays to follow the sun throughout the day and increasing its efficiency 30% over traditional stationary arrays.
Nations in the Middle East are planning to harness the vast amount of sunlight the region receives each year. Oil rich Abu Dhabi is building a $350 million, 100 MW powerplant which will later be increased to 500 MW capacity facility. Egypt is planning a 150 MW facility which combines solar and gas power and Jordan is looking to attract investors and technology from Europe for future solar development.
Several other countries are investing in solar power plants, such as South Korea. The country, which recently built a 2.2 MW solar energy system, has existing 2 MW and 1 MW facilities. Earlier this year, Korea commissioned the development of two more solar energy systems, a 2.5 MW plant and a 19 MW plant which will generate a combined 30 million kWh of clean electricity annually.
In Canada, Ontario has invested $100 million into Canada’s first solar power plant with two 10 MW solar power facilities in Sault Ste. Marie in Northern Ontario. The power plants, developed by Pod Generating Group, are expected to be operational by the end of 2008 and will connect to the local power grid, generating enough electricity to power 7,000 homes.
Canadian Solar Inc. (CSI), a Canadian solar module supplier, has been busy supplying its technology to major solar power plant projects in Germany and Spain.
The Canadian Solar Industries Association (CanSIA) believes that despite global growth rates exceeding 25% a year, Canada is lagging behind other developed countries. Canada ranks 14th of 20 reporting International Energy Agency (IEA) countries in the deployment of PV and 17th of 22 reporting countries for solar thermal energy applications. International growth elsewhere has been the result of progressive government policies aimed at reducing prices through economies of scale, establishing key infrastructure foundations and supporting the development of sustainable solar markets, notes CanSIA.
In Canada, the development of solar technologies is heavily dependent on support from the Canadian investment community. However the absence of any significant Canadian solar programs has resulted in a lack of awareness of this technology amongst investors, consumers, and decision makers.
CanSIA is working towards the implementation of a national renewable energy strategy in Canada, which is part of an overall National Energy Strategy. It is also seeking the integration of solar with other energy efficiency and demand side management policies, and increased government funding of solar research and development, focused funding for model solar communities and other demonstration projects.
Despite the major investments in solar energy projects around the world, solar generated power is expected to remain a small percentage of global power generation for the foreseeable future, due mainly to its lack of efficiency. Even the most efficient solar cells utilize only 20% of the energy absorbed.
Solar cells for major heat and electricity generating projects require a significant surface area. For example, the 20 MW Korean plant is expected to be 600,000 m2, or 80 football fields in size. As solar technology becomes more efficient and sun tracking technology becomes more widespread, the area required for equivalent facilities will become less.
The dependency of solar power on sunlight could be viewed as a drawback, but there are all ready solutions in place. Excess energy absorbed throughout the day can be stored in batteries for later use on overcast days. Solar power can also be a combined with wind power to improve the efficiency of both, with the wind energy working in periods of adequate wind, while solar batteries store energy for use in periods of low wind.
Regardless of its drawbacks, solar energy is clean and depends on an essentially unlimited resource, and what it lacks in efficiency, it makes up for in versatility. For now it is best used as a supplement to other energy sources, but as its efficiency grows solar could become our most important energy source.
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