A fruitful interdisciplinary collaboration between Prof. Haim Rabinowitch of the Hebrew University’s Robert H. Smith Faculty of Agriculture, Food and Environment, and Prof. Lioz Etgar of from the Institute of Chemistry at the Hebrew University yielded a prototype for a new solar cell whose efficiency has been technologically proven and whose performance stands to dramatically change the rules of the game regarding solar energy and agricultural production. This innovative solar cell is designed to fully cover agricultural areas (including greenhouses, orchards, and fields) and water bodies while simultaneously generating green electricity and agricultural  production, without interruption of natural habitats under the PV panels, without using up natural resources, and without harming the environment.

The new solar cells are based on perovskite crystals and are produced in a relatively straightforward process using cheap and available materials. A chemical substitution makes the solar cells transparent to the most efficient area of the light spectrum that drives photosynthesis, while a great part of the rest of the light energy is transformed into electricity. Prof. Lioz Etgar explains: “For years, it has been obvious that most light energy in agricultural greenhouses is wasted, as plants use only a fraction of the sunlight energy, while the rest is radiated back into the atmosphere. In greenhouses, it becomes heat energy, that growers need to get rid of during most months of the year.” He continues: “Our solution maximizes the production of solar electricity on agricultural land by up to 300%.” The new cells are expected to have much lower production costs than silicon-based photovoltaic cells, and will also significantly improve cultivation conditions in greenhouses by reducing heat, lowering greenhouse gas emissions and evapotranspiration, saving water, and protecting crops from weather damage, as well as offering partial protection from pests and disease.

All existing technologies for the generation of green power on agricultural lands deploy silicon-based photovoltaic cells, which are either fully opaque or only partially transparent to most of the light spectrum or laid in alternative arrays, thus resulting in lower efficiency of power generation and concomitantly reduced agricultural production. Prof. Haim Rabinowitch: “This new development, which can be installed over any agricultural lands and any bodies of water, will make it possible to fully replace the roofs of most agricultural greenhouses, reduce heat levels and evapotranspiration in orchards and fields, and impairment of many fresh-water and coastal marine ecosystems on which rafts or islands of solar cells are installed.”

Calculations based on current data indicate that the use of these new cells will reduce the price of energy per kWh in Israel by 75%, which will lower agricultural costs and increase agricultural income and profitability. This is nothing less than a revolution. Israel has a total of around 90,000 dunams (9,000 hectares) of greenhouses. Covering the greenhouses roofs of half of these with the new solar cells will provide a quantity of green electricity that enable Israel to exceed its 2050 national targets for green electricity production and carbon emission reduction. To give a greater idea of the economic potential of this development, the Mediterranean basin alone holds around 2 million dunams (200,000 hectares) of greenhouses.

A study published in 2018 in Global Food Security showed that the value of vegetable cultivation constitutes around 30% of the overall value of all crops combined, measured at around $1.85 billion. The process of photosynthesis with which all crops are grown uses about 10% of the total available light energy from the sun. Thus, it was only a matter of time before groundbreaking creative research would come up with a far more efficient solution for the combined production of electricity and agricultural produce, utilizing the remaining 90% of solar energy that is not used in photosynthesis.

The idea developed by Prof. Rabinowitch and Prof. Etgar, and their research program, were assessed by the Israel Innovation Authority, which provided a generous research grant. The proven results of this research were promoted by the Hebrew University’s technology-transfer Yissum and formed the basis for partnership with the Red Solar Flower initiative, led by Dr. Shai Danziger and Ilan Sharon. The successful research project to develop the solar cells, along with the Yissum-Red Solar Flower partnership, were recently recognized with the award of first place in the Energy Tech Challenge, led by the Digital SolarEdge company, as part of the Climate Solutions Prize organized by Start-Up Nation Central.

Excavating ancient DNA from teeth, an international group of scientists peered into the lives of a once thriving medieval Ashkenazi Jewish community in Erfurt, Germany. The findings, shared today in the Journal Cell, show that the Erfurt Jewish community was more genetically diverse than modern day Ashkenazi Jews.

About half of Jews today are identified as Ashkenazi, meaning that they originate from Jews living in Central or Eastern Europe. The term was initially used to define a distinct cultural group of Jews who settled in the 10^th century in Germany's Rhineland. Despite much speculation, many gaps exist in our understanding of their origins and demographic upheavals during the second millennium.

“Today, if you compare Ashkenazi Jews from the United States and Israel, they’re very similar genetically, almost like the same population regardless of where they live,” shared geneticist and co-author Professor Shai Carmi of the Hebrew University of Jerusalem (HU). But unlike today’s genetic uniformity, it turns out that the community was more diverse 600 years ago.

Digging into the ancient DNA of 33 Ashkenazi Jews from medieval Erfurt, the team discovered that the community can be categorized into what seems like two groups. One relates more to individuals from Middle Eastern populations and the other to European populations, possibly including migrants to Erfurt from the East. The findings suggest that there were at least two genetically distinct groups in medieval Erfurt. However, that genetic variability no longer exists in modern Ashkenazi Jews.

The Erfurt medieval Jewish community existed between the 11^th and 15^th centuries, with a short gap following a 1349 massacre. At times, it was a thriving community and one of the largest in Germany. Following the expulsion of all Jews in 1454, the city built a granary on top of the Jewish cemetery. In 2013, when the granary stood empty, the city permitted its conversion into a parking lot. This required additional construction and an archaeological rescue excavation.

“Our goal was to fill the gaps in our understanding of Ashkenazi Jewish early history through ancient DNA data,” explained Carmi. While ancient DNA data is a powerful tool to infer historical demographics, ancient Jewish DNA data is hard to come by, as Jewish law prohibits the disturbance of the dead in most circumstances. With the approval of the local Jewish community in Germany, the research team collected detached teeth from remains found in a 14th-century Jewish cemetery in Erfurt that underwent a rescue excavation.

The researchers also discovered that the founder event, which makes all Ashkenazi Jews today descendants of a small population, happened before the 14^th century. For example, teasing through mitochondrial DNA, genetic materials we inherit from our mothers, they discovered that a third of the sampled Erfurt individuals share one specific sequence. The findings indicate that the early Ashkenazi Jewish population was so small that a third of Erfurt individuals descended from a single woman through their maternal lines.

At least eight of the Erfurt individuals also carried disease-causing genetic mutations common in modern-day Ashkenazi Jews but rare in other populations—a hallmark of the Ashkenazi Jewish founder event.

“Jews in Europe were a religious minority that was socially segregated, and they experienced periodic persecution,” described co-author Harvard University. Although antisemitic violence virtually wiped-out Erfurt’s Jewish community in 1349, Jews returned five years later and flourished into one of the largest in Germany. “Our work gives us direct insight into the structure of this community.”

The team believes the current study helps to establish an ethical basis for studies of ancient Jewish DNA. Many questions remain unanswered, such as how medieval Ashkenazi Jewish communities became genetically differentiated, how early Ashkenazi Jews related to Sephardi Jews, and how modern Jews relate to ones from ancient Judea.

While this is the largest ancient Jewish DNA study so far, it is limited to one cemetery and one period of time. Nevertheless, it was able to detect previously unknown genetic subgroups in medieval Ashkenazi Jews. The researchers hope that their study will pave the way for future analyses of samples from other sites, including those from antiquity, to continue unraveling the complexities of Jewish history.

“This work also provides a template for how a co-analysis of modern and ancient DNA data can shed light on the past,” concluded Reich. “Studies like this hold great promise not only for understanding Jewish history, but also that of any population.”

The research team, of over 30 scientists, included HU’s Shamam Waldman, a doctoral student in Carmi's group, who performed most of the data analysis.