By Karin Kloosterman
Solar energy is an exciting option to greenhouse gas producing power sources, because the sun offers unlimited power, and zero carbon emissions. But to make it a real-world energy alternative, kinks in the system need to be addressed.
One of the biggest drawbacks to using solar energy is its unreliability: the sun's rays are not constant, and the power cannot be stored. The Israeli company EDIG, working in traditional markets of electro-mechanics since 1971, believes it has the solution, in the form of a low-cost hybrid generator.
Through subsidiary EDIG Solar, the company plans to make solar energy a viable power alternative. The company's power plant is hybrid, meaning that like electric cars, the system's turbines can adapt to more than one energy source.
During a rainy day, the solar turbines can switch over and run on traditional or alternative fuel.
"It's modular, meaning it can easily be increased in size, and it is flexible in terms of fuel use. It can be powered by bio-diesel, bio-gas or fossil fuels," explains the company's CTO Pinhas Doron, an engineer.
When it comes to alternative energy options, one technology does not fit all, he says. "Every application has to be examined on its own merit, and the best solution applied to it. Our solution works well for grid connected electricity, where there is ample sun."
Based on the research of Prof. Jacob Karni, director of the Center for Energy Research at the Weizmann Institute in Israel, EDIG's technology attracts the sun and concentrates it by way of tiny mirrors on the ground.
The thermal energy generated by the sun drives turbines in a tower, the same turbines that can be powered by traditional fuel, the moment a cloud passes overhead, or at night when the sun sets.
And in doing this, "our hybrid solution addresses the issue of intermittency of solar radiation," says Doron.
Admittedly, he will not try to sell this solution to the northern states in America, or to Canadians, but it would be perfect for places where there is direct radiation, such as in the southwest USA, southern Spain, or in India, he says.
EDIG recently built a 100 kW pilot plant study in Nanjing, China. It included a power conversion unit (a solarized gas turbine and a solar receiver), which was installed on a tower, and a field of heliostats (sun-tracking mirrors).
The unit was fully operational and supplied power to the local electric grid, says Doron. "We proved our concept - we connected to the grid and operated seamlessly," he reports. The next step is building a plant in Israel's Arava Desert, which should be ready by next year.
While the company is not reinventing the "solar" wheel, its IP rests in at least two areas, says Doron. It's solar "receiver" is based on patented Weizmann technology, and the modifications on the turbine, which allows it to switch energy sources and at high temperatures, without the user noticing it, was difficult to overcome.
Of course, when the solution is being operated in hybrid mode, there are "no zero emissions," says Doron. "But during optimal conditions of sunshine, it could be. Fuel use would be minimal," he stresses.
Will this be a solar solution we can all live with? Avraham Israeli, a private consultant and previously a trade exec at Israel's Export Institute for clean technologies, recommends EDIG as the most promising solar energy company in Israel, if not the world.
"The company is implementing a technology of solar thermal electricity generation. It seems to be the most cost-effective technology in the market," he told ISRAEL21c.
And if the new hybrid plant from Israel doesn't live up to the promise and hype, there is always the sun.