Monday, March 9, 2009
The term “technology” refers to the application of knowledge for practical purposes.
The field of “green technology” encompasses a continuously evolving group of methods and materials, from techniques for generating energy to non-toxic cleaning products.
The present expectation is that this field will bring innovation and changes in daily life of similar magnitude to the “information technology” explosion over the last two decades. In these early stages, it is impossible to predict what “green technology” may eventually encompass.
The goals that inform developments in this rapidly growing field include:
Sustainability - meeting the needs of society in ways that can continue indefinitely into the future without damaging or depleting natural resources. In short, meeting present needs without compromising the ability of future generations to meet their own needs.
“Cradle to cradle” design - ending the “cradle to grave” cycle of manufactured products, by creating products that can be fully reclaimed or re-used.
Source reduction - reducing waste and pollution by changing patterns of production and consumption.
Innovation - developing alternatives to technologies - whether fossil fuel or chemical intensive agriculture - that have been demonstrated to damage health and the environment.
Viability - creating a center of economic activity around technologies and products that benefit the environment, speeding their implementation and creating new careers that truly protect the planet.
Examples of green technology subject areas
Perhaps the most urgent issue for green technology, this includes the development of alternative fuels, new means of generating energy and energy efficiency.
Green building encompasses everything from the choice of building materials to where a building is located.
Environmentally preferred purchasing
This government innovation involves the search for products whose contents and methods of production have the smallest possible impact on the environment, and mandates that these be the preferred products for government purchasing.
The invention, design and application of chemical products and processes to reduce or to eliminate the use and generation of hazardous substances.
Nanotechnology involves the manipulation of materials at the scale of the nanometer, one billionth of a meter. Some scientists believe that mastery of this subject is forthcoming that will transform the way that everything in the world is manufactured. “Green nanotechnology” is the application of green chemistry and green engineering principles to this field.
Solar: Solar Thermal: Making Electricity From The Sun's Heat
Solar thermal electric power plant generates heat by using lenses and reflectors to concentrate the sun's energy. Because the heat can be stored, these plants are unique because they can generate power when it is needed, day or night, rain or shine.
Solar thermal electric systems operating in the US today [Solar Parabolic Troughs] meet the needs of over 350,000 people (equal to the population of the city of Fresno, CA or Miami, FL) and displace the equivalent of 2.3 million barrels of oil annually.
Solar thermal power plants create two and one-half times as many skilled, high paying jobs as do conventional power plants that use fossil fuels.
A CEC (California Energy Commission) study shows that even with existing tax credits, a solar thermal electric plant pays about 1.7 times more in federal, state, and local taxes than an equivalent natural gas combined cycle plant. If the plants paid the same level of taxes, their cost of electricity would be roughly the same.
Solar Two, a "power tower" electricity generating plant in California, is a 10-megawatt prototype for large-scale commercial power plants. It stores the sun's energy in molten salt at 1050 degrees F, which allows the plant to generate power day and night, rain or shine. Construction was completed in March 1996, and it is now in its three year operating and testing phase. (source: Southern California Edison)
Over 700 megawatts of solar thermal electric systems should be deployed by the year 2003 in the U.S. and internationally. The market for these systems should exceed 5,000 megawatts by 2010, enough to serve the residential needs of 7 million people (larger than the state of Georgia) which will save the energy equivalent of 46 million barrels of oil per year.
Utilizing only 1% of the earth's deserts to produce clean solar electric energy would provide more electricity than is currently being produced on the entire planet by fossil fuels.
The sun's heat can be collected in a variety of different ways: Solar Parabolic Troughs consist of curved mirrors which form troughs that focus the sun's energy on a pipe. A fluid, typically oil, is circulated through the pipes which is used to drive a conventional generator to create electricity. Solar Parabolic Dish systems consist of a parabolic-shaped concentrator (similar in shape to a satellite dish) that reflects solar radiation onto a receiver mounted at the focal point at the center. The collected heat is utilized directly by a heat engine mounted on the receiver which generates electricity. Solar Central Receivers or "Power Towers" consist of a tower surrounded by a large array of heliostats. Heliostats are mirrors that track the sun and reflect its rays onto the receiver, which absorbs the heat energy that is then utilized in driving a turbine electric generator.
- The myth about baseload power is always used to attack solar electricity, which of course is only available during daylight hours. This myth is based on misconceptions.
Firstly, not all forms of electricity generation are required to supply baseload and there is a very valuable place for technologies that can supply power during the day when the demand for electricity is greater than overnight.
Secondly, the rapid advancement in solar thermal electricity generation, producing steam to drive a turbine and generator, can be easily combined with geothermal energy (hot rocks) which can produce steam day and night.
Australia, USA, Spain, South Africa, Israel and other countries are very well placed to deploy these technologies because they have many locations where power grids run through very sunny inland where geothermal energy exists. Australia is a particularly good example of this.
Thirdly, should it be considered necessary for solar energy to be available overnight, there are now very good prospects for the commercialisation of several different energy storage technologies that will make this possible.
These include vanadium redox and inc-bromine batteries, both of which are being developed in Australia and elsewhere. And sometimes as is the case with Australia there is government financial support for demonstration installations.
In summary, an electricity system that uses a mix of different renewable technologies such as geothermal, wind and wave power along with some energy storage and a good geographical dispersion of solar thermal energy generation, will have just as much ability to supply reliable baseload power as the current coal based generation system.
One should just remember, in less than an hour every day the sun produces more energy than we all need globally in a year. We just need to capture some of it. 1% will more than suffice to meet our current and future world needs.
Stirling Energy Systems, Inc. (SES)/Boeing, 25 kW Dish Stirling system at sunset.
Source: National Renewable Energy Laboratory, Photographic Information Exchange.
Solar thermal devices use direct heat from the sun, concentrating it in some manner to produce heat at useful temperatures. The modern solar industry began with the oil embargo of 1973-1974 and was strengthened with the second embargo in 1979. The growth of the solar industry during this period of fuel shortages and high prices (1974-1984) soared from 45 solar collector manufacturing firms to 225 firms.The solar market was helped during this period by government assistance, both Federal and State. Currently, solar thermal devices do everything from heating swimming pools to creating steam for electricity generation.