Thursday, May 7, 2009
The use of renewable energy sources to replace coal, oil and natural gas is one of the primary methods for achieving a more sustainable future. Renewable energy sources include biofuels, solar energy, wind energy, and geothermal energy. Below is a discussion of each of these sources as community or regional energy sources. The use of these renewable energy sources on individual buildings is later in this blog under the section dealing with sustainable building design.
Monday, May 4, 2009
Biofuels refers to renewable plant matter that is used as a replacement for coal, oil or natural gas to produce energy. This can either be through direct combustion or through the conversion of the plant matter to synthetic fuels such as biodiesel. Biofuels become even more efficient when the plant is harvested for food and only the waste materials from the plant is converted to energy.
Geothermal energy production is a renewable energy source that extracts the heat from the earth's interior. The cost of geothermal energy production is greatly dependent upon how close to the earth's surface are located geothermal vents. In locations such as Iceland and Hawaii where there exists active volcanic activity, geothermal energy is an attractive source of renewable energy. Pictured above is a geothermal power plant built in Iceland.
Solar power, or energy from the sun, is by the earth's most abundant renewable energy source. Unfortunately, while having great potential, last year solar energy production accounted for only 0.02 percent of the world's energy consumption. With concern about global warming, however, governments are providing financial incentives for solar energy production, which helps to create demand and bring down the cost of solar energy technologies. Also, new approaches for solar energy production are being developed, such as that illustrated above where solar rays are concentrated in a single collecting mirror that allows for the building of large solar energy power plants. Examples of such solar energy power plants include the 46 MW Moura solar power plant in Portugal, the 40 MW Waldpolenz solar power plant in Germany, and the 11 MW PS10 solar power plant (illustrated above) in Seville, Spain.
Wind energy is another form of renewable energy. Modern wind turbines have become very efficient at transferring the energy of the wind to electricity. To demonstrate the potential of wind energy, electrical generation from wind turbines grew by 28.8 percent world-wide last year. Two innovative new uses of wind energy are: (1) specially designed new wind turbines that can be mounted on the roofs of urban buildings; and (2) the idea of creating a smart grid where wind energy can be exported from areas of high winds to urban areas needing the energy. Another innovative proposal is to build a grid of wind turbines in the upper midwest of the U.S. to provide cheap energy to extract natural gas from lands containing oil shale.
The heating, cooling and lighting of our buildings accounts for 48 percent of all U.S. energy consumption. As such, building energy usage is the greatest contributor to green house gases and global warming. This will only increase as the world becomes more urbanized and the built environment represents a greater and greater portion of our environment. Stormwater runoff from buildings is also one of the greatest non-point sources of water pollution, while the manufacturer of synthetic materials used in the construction of buildings leads to hazardous waste and an increasing number of "sick" buildings. Following is a discussion of methods of constructing "green" buildings so as to promote a more sustainable environment.
Green roofs are one of the most visible ways to build more sustainable, "green" buildings. A study conducted for Toronto, Canada estimated that the installation of green roofs on buildings could: reduce the heat island effect of urban areas by 1 to 2 degrees C, reduce smog alerts in cities by 5 to 10 percent, absorb CO2 emissions from automobiles and thus reduce green house gases, reduce the energy needs of buildings for heating and air conditioning, filter storm run-off and thus reduce water pollution, and expand recreational and open space in urban areas by creating roof-top gardens.