When officials from AORA cut the blue ribbon to launch the Tulip CSP system in desert country north of Almeria, Spain, I was able to sit with Pinchas Doron, PhD, the AORA Solar chief technology officer, to learn more of this innovative hybrid system. What follows is a condensed version of that interview.
Q. Tell me about the history of this hybrid CSP system.
A. The core technology, the enabling technology – it started at Weizmann Institute of Science. Weizmann has a solar tower facility – built in 1989. In 1992 I joined that group initially on a part-time basis before finishing my PhD. It was there that we developed the ideas of what we call the DIAPR (directly irradiated annually pressurized receiver). This later evolved into that solar receiver that we have now, which basically is the device that heats compressed air to the temperature that is required to run an air turbine.
Q. What happened then?
A. We created the first unit that heated air at a much higher temperature than what we need here because we later tailed it to You don’t need to heat to the 1300 degrees, you heat only to the 1000 degrees that you need.
Q. The micro turbine is powered by hot air from the sun that is being reflected in the mirrors, not gas, like many think.
A. That solar receiver that we have now, which basically is the device that heats compressed air to the temperature that is required to run an air turbine – common name is gas turbine. People think it is a turbine that runs on natural gas, but it is not. It is a turbine that runs on air. People often misunderstand – so how do you run a gas turbine with sun?
Q. Your first ‘proof of concept’ for the system took place in Nanjing, China five years ago, followed by a system in Israel.
A. In 2009 we started our first prototype in the southern part of Israel. We ran that system under various operating conditions and came to a lot of obstacles along the way. And following those lessons we upgraded the design of many of the system components and came to build this plant that is now here. In parallel, we are now operating the system in Israel that is almost the same as this one. So we’ll basically have twin units.
Temperatures in the Tulip system’s air turbine measure 1000 degrees Farenheit”]AORA hybrid CSP Tulip system in SpainQ. In Israel you supply power to the grid?
A. We were the first ones in Israel to go through that process of getting the authorities approval to build such a thing and connect to the grid and have the Israel Electric Utility – which is a state-run utility – to approve our connection to the grid. And understand I never knew there were so many divisions of Israel Electric until each one of them wanted to visit. But they were satisfied; they were satisfied with what they saw. So they shaved on our on beard – that’s a Hebrew expression: shave on somebody else’s beard so you don’t get the cuts yourself. So actually now everybody was satisfied. Our beards were shaved – and we didn’t get cuts, by the way.
Q. The technology is such a complete solution for renewable energy using solar. Why has there not been a larger following of your achievements?
A. I think that we’ve probably been under the radar even though we had this first launch in 2009. But most people considered us as being under the radar. Most people – the premise is to go to large plants, large units. We can do a large plant but our units will stay as those modular units. We’re quite unique.
Q. Talk about your business plan.
A. The business plan would be to do clusters of units – maybe tens of units, maybe hundreds – which would start initially from a small number of units that will help gain the confidence of this new technology. By building a cluster, you could much easier finance. You build groups, then you start generating income and then you build the next so you have a phased financing, basically, and a phased matching income at the other end. We would go initially to grid-connected installations. We will look for places where we can benefit from the discriminator of providing heat as well – of being flexible in operation and flexible in terrain, which is also extremely important. The key is flexibility. As we move along we also get into the off-grid market – a lot of places where the grid is either absent or not reliable. And there are a lot of places like this. Over there such a solution would be very good, actually. Again, I like to look at it as electricity – it’s not just electricity, it’s an energy solution.
Q. How is the turbine powered in this hybrid system?
A. The turbine can run on solar only, can run on solar, augmented by fuel, and we can run fuel-only. Now the fuel that we can use can be bad fuel, but it can also be nice fuel – it can be biogas, synthetic gas – whatever you could look at that would be green maybe.
Q. Do you consider adding sustainable fuel or biogas to your hybrid technology?
A. You could also use things that you need to take care of like the date plantations in the southern part of Israel. They have all this biomass that has fallen and you need to do something with it. You cannot really leave it in place. Or cow manure – you need to do something with it. Take that thing – not all processes, some processes are available that would use heat from the excess of the turbine – take that cow manure, or other stuff and generate renewable fuel that would in turn feed the turbine when there’s no sun.
Q. Like methane?
A. Yeah. So there you have sustainability – both in how you run your turbine and in taking care of that yucky matter that you need to do away with. So that is why we think that our system – even though we deal with the intermittency of the sun by burning fuel (natural gas) is still a sustainable system. It’s not a fossil power plant. You could use fossil fuels if you don’t have anything else and you need the power at night, okay? You do until you have another option, and when you have another option, modify the system to use another fuel is extremely simple, and fast, and probably not expensive….So that’s sustainability, as far as I can see it.
After the interview, Mr. Doron sent this message:
“I cannot recall if I really emphasized it, but one major discriminator of our system is minimal use of water (this being an air turbine), which is extremely important as many of the potential location for our systems do not have water to spare.”
Very important, indeed