Harry Zvi Tabor (1917–2015): The Father of Israeli Solar Energy
Harry Zvi Tabor was a visionary physicist and engineer whose work transformed solar energy from a marginal curiosity into a viable global industry. Often referred to as the "father of Israeli solar energy," Tabor’s innovations in the mid-20th century provided the theoretical and practical foundations for modern solar thermal collectors and low-temperature power generation.
1. Biography: From London to the Negev
Harry Zvi Tabor was born on March 17, 1917, in London, England. He displayed an early aptitude for the physical sciences, earning a B.Sc. in Physics from the University of London. Following his graduation, he worked in industrial research, specializing in instrumentation and measurement.
The trajectory of Tabor’s life changed in 1949, shortly after the establishment of the State of Israel. Prime Minister David Ben-Gurion, recognizing that the young nation lacked natural fossil fuel resources but possessed an abundance of sunshine, sought a scientist to spearhead energy research. Tabor immigrated to Israel and was tasked with creating the National Physical Laboratory of Israel (NPLI), which he directed for over two decades.
Living and working in Jerusalem, Tabor spent his career at the intersection of government policy and academic research. He earned his PhD from the Hebrew University of Jerusalem in 1959, focusing on the thermodynamics of solar energy. He remained an active researcher and advisor until his death in Jerusalem on December 15, 2015, at the age of 98.
2. Major Contributions
Tabor’s work was characterized by a rare combination of high-level physics and pragmatic engineering. His three most significant contributions are:
Selective Black Surfaces (The "Tabor Surface")
Before Tabor, solar collectors were inefficient because they lost almost as much heat as they absorbed. In 1955, Tabor developed the theory of selective surfaces. He created a coating—a "selective black" surface—that highly absorbed short-wave solar radiation but had very low emissivity for long-wave thermal radiation (heat). This allowed solar collectors to reach much higher temperatures (up to 100°C and beyond) than previously possible, making solar water heaters commercially viable.
The Solar Pond
Tabor pioneered the concept of the Solar Pond, a large-scale solar collector that uses a salinity gradient to prevent convection. In a normal pond, hot water rises to the top and loses heat to the atmosphere. In a Tabor solar pond, the bottom layer is extremely salty and dense; even when it heats up, it remains at the bottom, acting as a massive thermal storage bank. These ponds could generate electricity 24 hours a day, bypassing the "intermittency" problem of solar energy.
The Organic Rankine Cycle (ORC) Turbine
In collaboration with Lucien Bronicki, Tabor developed a low-temperature turbine capable of using heat from solar ponds or geothermal sources. Unlike traditional steam turbines that require high-temperature steam, the ORC turbine uses organic fluids with lower boiling points. This technology became the foundation for Ormat Technologies, now one of the world’s leading geothermal energy companies.
3. Notable Publications
Tabor was a prolific writer, contributing over 100 scientific papers and several books. His most influential works include:
- "Selective Radiation. I. Wavelength Discrimination" (1955): Published in the Bulletin of the Research Council of Israel, this paper laid the theoretical groundwork for selective surfaces and is considered a foundational text in solar engineering.
- "Solar Ponds" (1963): Published in Electronics & Power, this work detailed the mechanics of non-convecting salt-gradient ponds.
- "The Solar Pond as a Potential Energy Resource" (1980): An influential review that analyzed the economic and technical feasibility of solar ponds for large-scale power.
- "Solar Energy Research" (1959): His doctoral thesis, which synthesized his early findings on thermal conversion.
4. Awards & Recognition
Tabor’s contributions were recognized globally by both the scientific community and the State of Israel:
- The Israel Prize (1968): Israel’s highest honor, awarded to him for his contributions to engineering and technology.
- The Harvey Prize (1992): Awarded by the Technion – Israel Institute of Technology for his breakthroughs in solar energy.
- The Energy Globe Award (2014): A lifetime achievement award recognizing his role as a pioneer of sustainable energy.
- The Royal Society of Arts (UK): Elected as a Fellow.
- International Solar Energy Society (ISES): He served as President (1981–1983) and received the Farrington Daniels Award for intellectual leadership.
5. Impact & Legacy
The most visible legacy of Harry Zvi Tabor is found on the rooftops of Israel. Because of his research into selective surfaces, Israel became the first country to mandate solar water heaters in all new residential buildings. Today, over 90% of Israeli homes use "dudim shemesh" (solar boilers), saving the country approximately 4% of its total energy consumption annually.
Beyond Israel, Tabor’s work on the Organic Rankine Cycle paved the way for the modern geothermal industry. The company he helped inspire, Ormat, uses his turbine designs to provide clean energy to dozens of countries. His research into selective coatings is now standard in the manufacture of flat-plate collectors worldwide.
6. Collaborations
- David Ben-Gurion: While a politician rather than a scientist, Ben-Gurion was Tabor's primary patron, providing the political will and funding to establish solar research in the Negev desert.
- Lucien Bronicki: An engineer who worked under Tabor at the NPLI. Together, they developed the ORC turbine. Bronicki later founded Ormat to commercialize the technology they had researched together.
- The International Solar Energy Society (ISES): Tabor was a central figure in the internationalization of solar research, collaborating with American and European physicists during the 1950s and 60s to standardize how solar efficiency was measured.
7. Lesser-Known Facts
- The "Solar Refrigerator": In the 1950s, Tabor attempted to build a solar-powered refrigerator for use in developing nations that lacked electricity grids. While technically functional, it proved too expensive for mass production at the time.
- Musical Talent: Tabor was an accomplished cellist. He often remarked that the discipline required for music was similar to the precision required for physics.
- Religious Life: Tabor was a deeply religious Orthodox Jew. He famously balanced his scientific rigor with his faith, seeing the study of natural laws (like thermodynamics) as a way to understand the underlying order of creation.
- Anti-Pollution Visionary: Long before "climate change" was a household term, Tabor spoke about the "black smoke" of fossil fuels. His motivation was not just energy independence for Israel, but a cleaner, healthier environment for the world.