World's Tallest Solar Tower Take Shape in Israel

Most of us think of solar energy as consisting of photovoltaic solar panels, which make up 95 percent of the solar energy market. Solar towers, however, are proving to be a promising technology for commercial-scale installations as well.

Construction is now underway on the Ashalim Thermal Solar Power Station, where a vacant stretch of the Negev desert in Israel will be home to a 787-foot solar tower.

This is a big step in achieving Israel's goal to source 10 percent of its energy from renewables by 2020. The solar tower will produce enough electricity to power 121,000 Israeli homes, or meet 1 percent of Israel's total electricity needs. Although the project is privately funded, the Israeli government has agreed to buy the power at above-market prices. Construction is expected to conclude late next year.

Israel-based Megalim Solar Power is constructing the $773 million project, as a company formed by Alstom, BrightSource Energy and NOY Infrastructure & Energy Investment Fund. The 121-megawatt project uses BrightSource Energy's concentrating solar power (CSP) tower technology.

Unlike solar photovoltaic (PV) technology, which uses solar cells to generate a current of electricity, the tower uses solar thermal technology to generate heat. The project will use 50,000 computer-controlled mirrors with a dedicated Wi-Fi network to track the sunlight and focus it at a receiver at the top of the tower. The concentrated light creates temperatures up to 1,000 degrees Fahrenheit to convert a fluid to steam, which turns a turbine generator to produce energy.

Brightsource Energy technology was also used in 2013 in a three-tower project in Ivanpah, California. There was public outcry at that time over concerns about CSP technology incinerating birds, potentially killing tens of thousands of birds each year at the new project site. Subsequent investigations by biologists, however, have demonstrated that the impact on birds is less than some feared. Brightsource Energy has made progress in preventing this issue through several approaches. For more widespread use, CSP will need to become more cost effective.

The cost of solar PV technology has dropped dramatically in recent years, making it difficult for CSP to compete. CSP technology, however, does look promising for energy storage capabilities, thus producing power at night when solar PV technology cannot. But the Ashalim Thermal Solar Power Station will not have energy storage capabilities.

CSP projects require a lot of land and are only cost-effective on a large scale. Deployment is still relatively limited, with examples in the United States and Europe. Crescent Dunes, a recently completed project in Nevada, powers 75,000 homes throughout the day and night with a molten salt technology.

By agreeing to purchase the power for above-market prices, the project is essentially subsidized by the Israeli government. The ultimate goal for CSP is to cut costs and boost efficiencies, making such arrangements unnecessary.

"We're making strides in efficiency; we're making strides in compressing the time of construction," said Megalim's Chief Executive Eran Gartner. "We're going down a learning curve that will help us to offer solar energy at the most competitive rates."

Image credits: BrightSource Energy