Tabor, Harry Zvi

Harry Zvi Tabor is an Israeli physicist who propelled his nation’s solar industry to international prominence. While working at the National Physical Laboratory in Israel in the 1950s and 1960s, he introduced and promoted the concepts of selective coatings, the solar pond and participated in the development of the Organic Rankine Cycle turbine. He also promoted the utilization of Israel’s abundant solar resource. In that capacity, he is credited with the significant penetration of solar technologies into some segments of society, such as domestic hot water heating.

Shortly after the establishment of the state of Israel in 1948, one of the first acts of the Prime Minister, David Ben Gurion, was to set up the Research Council of Israel (RCI) to promote R&D that could harness science to help a new country having virtually no natural resources. Less than a year later, a new immigrant from the UK arrived in Israel - Harry Tabor, an applied physicist with industrial experience. He was given the ‘physics and engineering’ desk of the RCI, which included the task of setting up a national physical laboratory (NPLI) – on the British model – to put some order into the measurement units (British, metric and Ottoman) in use in the country. It was in this capacity that Tabor got involved in solar energy.

Harry Tabor exhibiting his solar collector at the  World Symposium on Solar Energy in Arizona in 1955.Harry Tabor exhibiting his solar collector at the World Symposium on Solar Energy in Arizona in 1955.Tabor established the Solar Energy laboratory within the National Physics Laboratory.  In 1955 Tabor published an interesting insight into selective absorption of solar energy. The foundation for this idea was the realization that "the spectrum of solar radiation and the spectrum of heat radiation for bodies heated to a few hundred degrees centigrade do not overlap by any appreciable amount". This basic idea led to the development of practical spectrally selective surfaces, highly absorbent in the solar spectrum, but highly reflective in the infrared, resulting in a surface where total absorptance for solar radiation is high while total emittance is low. Such surfaces have been developed which combine absorptivities of over 90% for solar radiation with emissivities of about 10% of that of a black body for heat radiation.  Tabor and his colleagues came up with two types of practical selective surfaces: Black Nickel and Black Chrome. Use of these surfaces in solar collectors reduced heat loss due to radiation by as much as an order of magnitude. Similar selective surfaces are commonly used today in commercial collectors.  The first Israeli prototype collector based on this approach was demonstrated by Prof. Tabor at the first World Symposium on Solar Energy, which took place in Arizona in 1955.

Tabor also contributed to the development of the Organic Rankine Cycle (ORC) turbine, a direct derivative of the early development of relatively low temperature flat plate collectors. This turbine was capable of operating even at the relatively low temperatures (below 100°C) provided by a solar flat plate collector array.  This invention was privatized in 1965 and an Israeli company Ormat was founded in Yavneh, Israel to convert the laboratory model into a commercial product. Cheap fossil fuel prices prevented its widepsread adoption.

Two experimental Solar Ponds were built under the supervision of Tabor. Ormat Corporation, the Israeli company who pioneered in building the ORC turbines, developed the large solar ponds and the matching turbines. A 5 MW ORC turbine was built for the Beit Ha'aravah pond, with support provided by the Israeli Ministry of Energy. 

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