PRINT THIS PAGE Something new under the sun
24/01/2007. Source:IVCJ. Dr. Daniel Kaftori, Co-Founder, Distributed Solar Power
Solar power can become a major source of energy at a competitive price, and the technology exists now, says Dr Daniel Kaftori in this IVCJ article. Background
Worldwide demand for renewable energy sources and technologies, including solar energy, has been growing rapidly in recent years. Driven by rising oil prices, environmental concerns and energy independence considerations, and fueled by government and local subsidies and incentives, the global solar energy market has been expanding at an explosive rate 25-50 percent annually over the last few years. The vast majority of new solar energy installations has been in grid-connected markets where welldeveloped electricity grid and energy infrastructure exist.
Although the current boom is powered by subsidies, the need for solar energy is real on both the national and private user levels. On the national scale, utilizing solar power reduces the dependence on foreign sources, addresses issues of limited global resources, helps reduce emissions and comply with international standards (the Kyoto Protocol), and is a "natural" built-in solution for peak shaving. In addition, solar energy is a perfect tool for distributed generation, allowing power generation in many small plants located at customer sites, rather than in a few centralized plants, thus increasing the stability, robustness, and security of the energy infrastructure.
At the user level, solar power can reduce energy expenses by saving the retail cost of energy. This includes generation, transmission, distribution and utility profits as well as taxes and tariffs. The savings are at their maximum since daylight hours when solar energy is available are typically when electricity costs are highest where differential tariffs are in effect. Additionally, private users can earn green credits that can be traded for emissions in the open market and enjoy a variety of incentives as well as positive public relations exposure.
The problem: collection costs and efficiency
In spite of the urgent need, solar power has not been able to become more than a minute and esoteric player in the global energy market, reflecting solar powers high price relative to conventional power sources. There are three principal reasons for this situation:
Contrary to common belief, the intensity of solar radiation that reaches the ground is not particularly high. To illustrate, consider a family car. In order to power it with solar energy at a level comparable to a standard gasoline engine, one would need to cover it with solar panels the size of two basketball courts! Of course, this car would only operate during the daytime in sunny weather. Capturing substantial amounts of solar energy requires very large collection areas thus pushing up the price.
Most commercially available solar energy technologies convert radiation to useful power at low efficiency about 15 percent on average. Thus, most energy reaching us is wasted.
Most commercial technologies make use of only one form of solar power either electricity, through the use of photovoltaic (PV) cells, or heat. Few make efficient use of both. Therefore, again, much of the energy is lost.
Concentrated collection offers a solution
Emerging technologies are beginning to address these issues and are showing great potential for reducing the price of solar power to levels that will allow it to compete directly with
conventional power even without government incentives. One such technology, developed by Di.S.P. Distributed Solar Power Ltd. of Migdal HaEmek, Israel, enables more efficient collection of incoming radiation.
The system shown above concentrates the radiation from a large area onto a small point using a curved mirror. The process is similar to what we did as children using a magnifying glass in the sun to burn paper and etch our names onto wood. This way, rather than cover a large collection area with expensive PV cells, an inexpensive mirror can be used to focus the light onto a much smaller area of PV cells. Since this technology requires only a few PV cells, much more advanced cells with a conversion efficiency of 35 percent and higher can be used.
These cells are more expensive, but their higher output well justifies their price and leads to a lower overall system price and reduced energy costs. Finally, with the concentrated radiation, high heat is produced. The heat can easily be collected and delivered to the customer for heating, solar cooling (where solar heat is converted directly into air conditioning and refrigeration), steam generation and process heat.
These techniques enable a number of goals: reduction of the cost of collecting radiation from a large area, employment of high efficiency PV cells, and utilization of both electricity and heat. The overall result is an extremely efficient system that can convert over 75 percent of the solar radiation to useful energy. An added benefit is that the system tracks the motion of the sun, thus collecting the maximum amount of available energy at all times. This allows the system to generate 30-40 percent more energy than stationary systems that do not track the sun and therefore miss out on much of the incoming radiation.
When all these benefits are combined, the end result is a system that can generate more energy than competing solar power systems at a much lower price. Moreover, in good solar conditions, the energy generated by the system can be less expensive than energy from conventional sources even without solar incentives, thus paving the way for solar energy to enter the mainstream of energy sources.
This article appeared in the Israel Venture Capital & Private Equity Journal (IVCJ). IVC Research Center publishes the Israel Venture Capital & Private Equity Journal, a quarterly review of trends and developments in the Israeli-related venture capital industry. IVCJ, distributed worldwide, is dedicated to provide wide-range coverage of Israel's venture capital industry. For more information please visit www.ivc-online.com
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