Solar energy

Sunday we heard a presentation on the “Deployment of Solar Power” by Daniel Minsky, an environmental engineer and owner of the company Dan Solar Engineering, Ltd. located in Jerusalem. Israel is so blessed by plentiful sunshine, that it seems obvious that there should be a stong component of solar power in our energy portfolio. But, still by far the largest component is fossil fuels, namely coal, oil and natural gas. The co-called alternative or renewable fuels have mostly only recently been developed. They include wind power, using large turbines that generate electricity directly, hydroelectric power, wave power and nuclear energy, each of these having their own advantages and disadvantages. Solar power can be used in three main ways: 1. as direct heating, for example in the “dud shemesh” that are a feature of Israeli rooftops, that heat water but do not produce electricity ; 2. arrays of mirrors that focus the sun’s rays on a heating tower, where water (or air) is used to generate electricity and 3. solar panels that have photovoltaic cells that generate electricity directly from the sun’s rays.

Although wind power would seem to be a relatively advantageous renewable resource, there are problems in that these usually cannot be adapted for individual use. Large “wind farms” of turbines can be found in the US, UK and around the world, but very few are used for individual houses. They also make a significant noise and are not located near inhabited areas. Arrays of mirrors, that turn with the sun’s direction, have been set up in southern Israel, in the US, Spain and elsewhere, and are likely to grow in number. One advantage of panels of photovoltaic cells is that they can be placed on almost any rooftop and can generate electricity that can be used in individual houses and buidlings to heat water and run a/c, lights and so on. One great advantage of this is that it is economically viable since although the initial cost of set-up is high, excess electricity can be sold to the national grid at competitive rates, and so the system pays for itself in 5-7 years. Also, no tax is paid (in Israel) on the income from the sale of electricity. Note that the cost of photovoltaic cells is being reduced, for example by recent developments in China. The chief drawback of solar power is of course that the sun does not shine at night, and so an alternative energy source is also required. Since it is very expensive currently to store the electricity in batteries, mostly the energy required at night (much less than during the day) is usually taken from the national grid.

Although these approaches seem attractive, they currently constitute only 1% of Israel’s total electricity needs, and comparable amounts in other countries. Nevertheless, Israel, like other countries, has committed itself in an agreement with the OECD to produce 5% of its total national needs by alternative means by 2014 and 10% by 2020. This means that there are subsidies and economic inducements for the development of “green” energy sources. However, the huge discoveries of oil and natural gas in the Mediterranean sea ca. 125 miles off Haifa, means that the Israeli Government might want to re-think its decision to provide subsidies for alternative sources of energy. Nevertheless, the utilization of these finds do not come cheap, and includes laying pipelines, building huge storage facilities (such as liquefied natural gas containers), changing the source of energy in power stations (e.g. from coal to natural gas), and providing security for all of this. Estimates for this are up to 40 billion shekels (or ca. b$10), and that’s before any of the fuels are used. So the need for cheaper, renewable and non-polluting energy sources is still very much a desirable alternative.

About the Author
Jack Cohen was born in London and has a PhD in Chemistry from Cambridge University. He moved to the US and worked at the National Cancer Inst. and then Georgetown Medical School. In 1996, he Moved to Israel and became Chief Scientist of the Sheba Medical Center. He retired in 2001 and worked as a Visiting Professor at Hebrew University Medical School for 5 years.