TexasIsHot – Energy Efficiency

Solar

Solar Energy

Basics

There are two ways to harvest solar energy for electricity.

Photovoltaic (PV devices) or “solar cells” change sunlight directly into electricity. When photons from sunlight strike a photovoltaic cell, they are absorbed, providing energy to generate electricity. Individual PV cells are made of semiconductors, such as crystalline silicon or various thin-film materials. PV cells are grouped into panels and arrays of panels. Thousands of houses and buildings around the world have PV systems on their roofs.

Solar Thermal/Electric Power Plants generate electricity by concentrating solar energy to heat a fluid and produce steam that is used to power a generator. Concentrating solar power technologies use mirrors to reflect and concentrate sunlight onto receivers that collect the solar energy and convert it to heat. This thermal energy can then be used to produce electricity via a steam turbine or heat engine driving a generator.

The four main types of solar thermal power systems are:

  1. Parabolic trough – Uses a long parabolic-shaped reflector to focuses the sun’s rays on a receiver pipe located at the focus of the parabola.
  2. Solar Field – Uses many parallel rows of solar parabolic trough collectors aligned on a north-south horizontal axis. At a central location, the fluid circulates through pipes so it can transfer its heat to water to generate high-pressure, superheated steam.  The steam is then fed to a conventional steam turbine and generator to produce electricity.
  3. Solar Dish – Uses concentrating solar collectors that track the sun, so they always point straight at the sun and concentrate the solar energy at the focal point of the dish. Mechanical power is created by compressing the working fluid when it is cold, heating the compressed working fluid, and then expanding the fluid through a turbine or with a piston to produce energy.
  4. Solar power tower – Uses hundreds to thousands of flat sun-tracking mirrors called heliostats to reflect and concentrate the sun’s energy onto a central receiver tower.  The energy can be concentrated as much as 1,500 times that of the energy coming in from the sun.

Opportunities

  • Solar energy systems do not produce air pollutants or carbon dioxide.
  • When located on buildings, they have minimal impact on the environment.
  • Conversion from sunlight to electricity is direct, so that bulky mechanical generator systems are unnecessary.
  • PV arrays can be installed quickly and in any size.
  • The environmental impact is minimal, requiring no water for system cooling and generating no by-products.

Challenges

  • The performance of a photovoltaic array is dependent upon sunlight.
  • The efficiency of most commercially available photovoltaic modules in converting sunlight to electricity ranges from 5% to 15%.
  • The amount of sunlight that arrives at the Earth’s surface is not constant. It varies depending on location, time of day, time of year, and weather conditions. Climate conditions (such as clouds or fog) have a significant effect on the amount of solar energy received.
  • Because the sun doesn’t deliver that much energy to any one place at any one time, a large surface area is required to collect the energy at a useful rate.
  • Some toxic materials and chemicals, and various solvents and alcohols are used in the manufacturing process of photovoltaic cells. Small amounts of these waste materials are produced.
  • Although sunlight is free, solar cells and the equipment needed to convert their direct-current output to alternating current for use in a house is expensive.

Future Trends

Covering 4% of the world’s desert area with photovoltaic devices could supply the equivalent of all of the world’s electricity. The Gobi Desert alone could supply almost all of the world’s total electricity demand.

Despite sunlight’s significant potential for supplying energy, solar power provides less than 1% of U.S. energy needs. This percentage is expected to increase with the development of new and more efficient solar technologies. Researchers around the world are trying to achieve efficiencies up to 30%.

Testimonials
  • "“As the Texas population continues to grow, so will our energy consumption needs. We must have tools that empower the consumer to choose their products and monitor their usage wisely. TexasIsHot.org is a great resource, which is exactly what Texans need in today’s deregulated market.”" - State Rep. Burt Solomons (R-Carrollton), Chairman of House State Affairs Committee
  • "In order to meet our goals, we need programs like the TexasIsHot campaign to help change the way people think about energy." - State Sen. Troy Fraser (R-Horseshoe Bay), Chairman of Senate Natural Resources Committee
  • "Texas leads the nation in wind power because it makes money, not because it makes us feel better. Texans are a practical, penny-wise people who I think will be happy to learn how to save a few bucks on their power bills with the common-sense advice at TexasIsHot.org."-Jerry Patterson, Commissioner of the Texas General Land Office
  • "If every Texas household adopted just a few of the dozens of energy efficiency strategies referenced on TexasIsHot.org, our air would be cleaner, our limited supply of natural resources would be better protected, and our wallets would be heavier..." Kip Averitt (R-Waco), Former State Senator and Chairman of Senate Committee on Natural Resources
  • ”The TexasIsHot campaign targets an important piece of the clean energy effort -- educating Texans on the way we use electricity and quantifying the financial and environmental costs associated with our use. By just reducing the amount of electricity we use and waste, TexasIsHot.org can show people how to save money..." State Sen. Kirk Watson (D-Austin)
  • "Fluctuating energy costs are really hurting Texas families and businesses, but by just making a few easy changes, Texans can cut down on energy waste. TexasIsHot.org is a tremendous resource which arms consumers with the information they need to save themselves money by becoming more energy efficient, and help our environment." State Sen. Rodney Ellis (D-Houston)
  • "Texas is the third fastest growing state in the nation with a net growth of 1,000 people each and every day. This brings many challenges including providing clean and affordable electricity. That is why I'm excited about TexasIsHot.org. This website is an instructional resource that will help Texans save on their energy bills at home and in the workplace..." State Rep. Phil King (R-Weatherford)
  • "Now, more than ever, Texans need to work together to conserve energy and to make more efficient use of the energy we consume. The TexasIsHot.org website is an extraordinary resource for people who want to save money and help conserve our precious natural resources..." State Rep. Rafael Anchía (D-Dallas)
  • "By partnering with the TexasIsHot Coalition we can extend our effort’s reach, leverage our resources, and ensure that Austin’s energy grid continues to be a test-bed for technologies, products, and services that will transform our state’s energy system." Brewster McCracken, Executive Director, Pecan Street Project
  • "The City of Houston is working harder than ever to make Houston green and energy efficient, but we need the help of every citizen. I would encourage everyone to take a moment to explore the TexasIsHot website to learn what we can all do to make Houston, and the rest of Texas, the green and energy efficient example for the rest of the nation." Mayor Annise Parker, Houston
  • "Energy efficiency is one of our top priorities. Partnering with the TexasIsHot Coalition will help us educate citizens and local businesses about energy-efficient practices in order to meet our goal of reducing residential and commercial electric use." Gavin Dillingham, Chief of Sustainable Growth – General Services Department, for the City of Houston
  • "We are excited about the new partnership that the City of Corpus Christi has entered into with the TexasIsHot Coalition. TexasIsHot.org provides a platform to educate policy makers, city employees and citizens on how to save money and help the environment by conserving energy..." Mayor Joe Adame, Corpus Christi
  • "I am excited that the City of Corpus Christi has joined the TexasIsHot Coalition and look forward to working with them to help Texans become smarter energy users. Energy efficiency is by far the best way for people to reduce their bills and help the environment, but we need education and outreach to make this happen." State Rep. Solomon Ortiz, Jr (D-Corpus Christi)
  • "Because of its fast growth and hot summers, Texas has to get smarter about energy conservation. I applaud the efforts of Corpus Christi and TexasIsHot to help businesses and residents reap the benefits of increased efficiency." Senator Juan “Chuy” Hinojosa (D-McAllen)
  • "Energy efficiency is the cleanest, quickest and cheapest way to get smart about energy use, saving both money and the environment. I applaud the TexasIsHot Coalition in their effort to educate Texans about the benefits of energy efficiency..." Luke Metzger, Director, Environment Texas
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