Energy Sources
Solar
Facts
The sun is the ultimate renewable resource. To capture it, photovoltaic cells absorb the energy in sunlight and cause electrons on a semiconductor to flow, producing electricity. Small solar arrays have become common on homes and other buildings. Structures can also be built to use passive solar heat to be distributed through walls and floors. At the same time, solar is an intermittent energy source: it can only work when the sun is shining. In order to overcome this intermittency, solutions from both the supply side and demand side must be considered. Traditionally, expensive fossil fuel-fired power plants had to provide the back up to intermittent resources such as solar and wind. In the future demand side solutions will be available where demand is reduced to accommodate this intermittency. New storage technologies will also be available.
Source: “SEIA Fact sheets.” Solar Energy Industries Association: http://www.seia.org/cs/government_affairs_and_advocacy/fact_sheets
The total energy from the sun that reaches the earth every year is 454 times annual global energy consumption.
Source: US Department of Energy; available: www.solardecathlon.org/pdfs/media_kit_2009.pdf
Government support for renewables grew to $37 billion in 2009, a year-on-year increase of nearly 43%. The volume of electricity produced from PV, biomass, geothermal and wind combined grew by 13% year on year. The main factors explaining the increase in renewables generation include changes in policies, larger purchasing obligations through programs such as renewable portfolio standards, and greater generation output owing to improved technological efficiency.
Source: “World Energy Outlook 2010.” International Energy Agency
Overview
The Demand for Solar Energy in the U.S. has grown 25% per year for the past 15 years.
Source: US Department of Energy; available: www.solardecathlon.org/pdfs/media_kit_2009.pdf
Building enough solar capacity to produce 10% of U.S. demand would require $450 billion to $560 billion between now and 2025, an average of $26 billion to $33 billion per year. In 2007, utilities spent an estimated $70 billion on new power plants and transmission and distribution systems.
Source: Clean-Tech; available: http://www.cleanedge.com/reports/reports-solarU.S.A2008.php
The world's largest photovoltaic plant, located in Canada, has a capacity of 97 MW. In just the past year, four photovoltaic plants with capacities greater than 60 MW have been built.
Source: PVresources.com; available: http://www.pvresources.com/en/top50pv.php
Around 10,000 homes in the U.S. run exclusively on solar electricity. In total, solar panels on homes produced 156 MW in 2009, double the total produced in 2008.
Source: Home Power Magazine
Source: “Home solar panels doubled electric output last year.” U.S.A Today, April 2010: http://content.usatoday.com/communities/greenhouse/post/2010/04/homes-solar-panels-doubled-electric-output-last-year/1
Designers can install solar arrays that are larger than needed so that excess generation can be “sold back” to the grid.
Source: Consumer Energy Council of America
Solar power could meet today's total U.S. electricity demand with photovoltaic systems covering only 0.4% of the nation in a high-sunlight area such as the Southwest — an area of about 10,000 square miles.
Source: US Department of Energy; available: www.solardecathlon.org/pdfs/media_kit_2009.pdf
The manufacture of silicon-based photovoltaics currently requires substantial energy; if that energy is produced from fossil fuels, it will result in emissions being released into the atmosphere. However, over their lifecycle, photovoltaic cells produce less harmful emissions. If all current electricity generation was replaced with photovoltaics, it would eliminate 89% of air emissions associated with electricity generation.
Source: “Emissions from Photovoltaic Life-Cycles”; Environmental Science and Technology; available: http://pubs.acs.org/doi/abs/10.1021/es071763q
The quality of its solar resources and its large uninhabited areas make the Middle East and North Africa region ideal for large-scale development of concentrating solar power. Solar power could be exported with relatively low transmission costs to Europe and to countries in sub-Saharan Africa.
Source: “World Energy Outlook 2010.” International Energy Agency
According to the IEA, large-scale solar PV generation costs will decline by 44% between this decade and the period between 2020 and 2035. Moreover, solar PV building costs are expected to fall by 47% in the same period.
Source: “World Energy Outlook 2010.” International Energy Agency
In October 2010 Germany—the largest PV market in the world—cut its feed-in tariff (which encourage the use of solar and other renewable energies) by around 13%. In July 2010, Italy and Spain also passed legislation to cut overall government support for solar power, although the cuts were lower than originally planned. Meanwhile, Belgium, France and Greece are also cutting feed-in tariff programs.
Source: “World Energy Outlook 2010.” International Energy Agency
Scientists are developing solar cells that are more than twice as efficient currently available solar cells. The U.S. Department of Energy predicts that the price of solar electricity will be cost-competitive with traditionally generated electricity in areas with high electricity prices.
Source: PV tech.org; available: http://www.pv-tech.org/product_briefings/_a/new_product_mitsubishi_electric_boosts_multicrystalline_cell_efficiency_to_/
Source: Source: “Ultra Efficient Photovoltaics”; M.I.T Technology Review; available: http://www.technologyreview.com/energy/18910/page1/
Source: Energy Information Administration; available: http://www.eia.doe.gov/oiaf/ieo/solar.html
Although solar power is projected to cost more than traditionally generated electricity in 2030, it could be more attractive if environmental effects are also considered.
Source: EIA; available: http://www.eia.doe.gov/oiaf/ieo/solar.html
Solar electric generating capacity is expected to grow by an annual average of 3.3% a year in the U.S. through 2030. If the equivalent increase in capacity were instead to be generated by fossil-fuel plants, a significant amount of greenhouse gas emissions would be released into the atmosphere.
Source: ”Annual Energy Outlook 2010”; Energy Information Administration
Excluding the manufacturing of solar cells, solar power produces no greenhouse gases, so it does not contribute to global warming. It also generates none of the atmospheric pollutants generated by combustion of fuels.
Source: U.S. Department of Energy
Solar: Opportunities
New technologies drive down costs.
New solar power technologies have the potential to dramatically reduce the cost of solar power production.
Scientific advances improve solar prospects.
Today, the most advanced commercially viable photovoltaic cells convert about 18% of the light that they receive into electricity. However, scientists have developed experimental photovoltaic cells that convert over 40% of the light that they receive into usable power. As this technology is developed it will dramatically reduce the cost of solar power.
Source: PV tech.org; available: http://www.pv-tech.org/product_briefings/_a/new_product_mitsubishi_electric_boosts_multicrystalline_cell_efficiency_to_/
Source: “Ultra Efficient Photovoltaics”; M.I.T Technology Review; available: http://www.technologyreview.com/energy/18910/page1/
Solar: Challenges
Solar power is still costly.
Solar power is the most expensive way to generate electricity. Its capital costs per kilowatt are about twice as much as wind and about four times as much as natural gas. The U.S. Department of Energy predicts that the cost of solar electricity will be competitive in areas with high electricity prices by 2030.
Solar power is supplemental.
Since solar photovoltaic systems operate only in the daytime, it is more common to think of them as supplemental resources that temporarily displace other sources of electricity that produce CO2. High usage could potentially increase challenges of intermittency.
Source: Consumer Energy Council of America; US Department of Energy
Source: “Will Solar Power’s Cost Make it a Tough Sell?”; Austin Business Journal; available: http://austin.bizjournals.com/austin/stories/2009/03/16/story1.html