Solar Energy Flower Power Tower

on March 05, 2012 at 11:00 AM

Like your typical garden flower, this tulip captures heat from the sun for energy. But unlike most flowers, this one is 115 feet tall and uses a combination of gas and mirrored heliostats to spin a gas turbine that creates electricity.

AORA‘s concentrated solar power (CSP) systems – designed in southern Israel where sunlight is abundant and water is scarce – uses pressurized air, rather than water, to spin a conventional gas turbine. If the air momentarily cools, from cloud cover for example, the tower automatically reroutes the air through a combustion chamber that can use anything from biogas and methane to natural gas and diesel to heat the air and spin the turbine.

With a 100 kW system up and running in Israel since 2009, and another launched in Spain, AORA is an infant in the solar scene and has yet to prove it can build utility scale power systems. But the promise of water-free and stable CSP has caught the eye of Michael Horner, CEO of Phoenix-based Sisener Engineering, who hopes to build a test facility in downtown Phoenix, Arizona that will act as both a research facility and demonstration site.

Besides producing stable base load power, the AORA system can function fully independent from the grid, something AORA CEO Zev Rosensweig said makes the technology a game changer in terms of power production in rural areas. And because it can use gas instead of solar power on rainy days, Rosensweig told Breaking Energy he thinks the technology is more reliable than molten salt storage systems that eventually cool during a long cloudy or rainy period.

Sisener Engineering is hoping to use the AORA tulip tower to build independent energy generation systems for industrial sites.

“They are looking at our technology as a gas generation that works on solar during the day, whereas we see it as the opposite,” Rosensweig said. “We see this as being far superior to storage systems, which besides being inefficient, the problem is what if you have two cloudy days in a row?”

For more coverage on the solar sector on Breaking Energy, click here.

Financing The Flower

But Solar CSP, which costs around $5 million/MW, is hard to finance, because it takes much longer to build than PV systems, and can leave investors waiting as long as five years before they begin to see any return on investment, said Rosensweig. He said he hopes investors will finance smaller cheaper pilots that can be proven and then with time can slowly be expanded as they attract more investment.

“That gives us flexibility that other plants don’t have. We can build 100 kW at a time. We have 1,000 building blocks,” Rosensweig said.

He hopes that utilities and investors will treat the AORA tulip system like a stable gas plant and not like an intermittent PV system that could trip offline at any moment.

But financing for the American pilot program is still under negotiation and may prove to be the biggest hurdle for the tulip tower.

Back To Nature

When AORA decided to commercialize the pressurized-air CSP technology, originally developed in Israel’s Weizmann Institute of Science in the 1980’s, Rosensweig said the company wanted to make it look as “green” as possible.

The company commissioned Israeli architect Haim Dotan to design something that would both mimic nature and be aesthetically acceptable if it were to be built close to rural homes or villages.

Renewable energy designs inspired by natural elements have become more common as companies seek to emphasize the “green” factor of their technology. In early February, Spanish architect Xabier Pérez de Arenaza released the uTree, a metal tree with approximately 77 solar cells on each leaf, complete with a rotation engine that allows the leaves to track the sun throughout the day. The vision is that cities can place the uTree in parks or on sidewalks for both an energetic and aesthetic experience.

AORA was hoping for a similar effect. The result of Dotan’s efforts was, “the desert flower,” which looks like a giant flower and when deployed en masse, could resemble a giant field of tulips, Dotan told Breaking Energy.

“The concept is that the sun turns the desert into a blooming field, a garden of flowers and we chose the flower as an element that really symbolizes the sun, solar energy,” Dotan said.

As countries around the world move aggressively towards renewable energy goals and greenhouse gas emission caps, the idea was to create an energy system that looks like nature just as much as it aims to protect natural resources by capturing sunlight.

Dotan emphasized that the AORA tower was inspired by nature, but does not dare imitate it: “I wish we could copy nature but we are not God,” he said.