Published on November 19th, 2013 | by Tina Casey8
Tulips And Hot Oil: Solar Power Mashup In Israel
November 19th, 2013 by Tina Casey
For those of you who thought concentrating solar power was losing the fight for hearts, minds, and profits, take a look at a couple of CSP plants in Israel’s Arava region. One features a bright yellow tulip-shaped tower and another is based on parabolic troughs and heated oil. Along with other nearby solar farms in the works, they are part of an ambitious plan to make the entire region energy independent within a few years.
As for profitability, according to a 2012 report by IRENA (the International Renewable Energy Agency), the levelized cost of energy for concentrating solar power is currently high, primarily because the cost of building a CSP plant is high.
However, IRENA also concludes energy storage enhancements will bring costs down, and the outlook is good for technological improvements that increase efficiency while reducing the cost of installation and operation.
With that in mind, let’s dig into those two aforementioned plants. They are both demonstration scale facilities and test beds for ramping CSP up to the next level.
The Mighty CSP Tulip
AORA is the company behind the tulip-themed CSP facility in Israel, which really is called Tulip™. It is located at Kibbutz Samar about 34 kilometers north of the tourist city of Eilat, and CleanTechnica had the opportunity to visit it last week during a tour sponsored by the Israeli organization Kinetis.
Even without poking too far around into the technology, you can see where some of the cost efficiencies are headed. For one thing, the 100-kW “micro-plant” is a modular design built around a single tower, so it can be expanded with a minimum of added design costs. At utility scale, you’ll see a vast field of Tulips, each surrounded by its own heliostats (special mirrors that focus sunlight on the top of the tower).
Tulip is also designed as a hybrid plant that uses biogas from a nearby livestock operation (see here, here, and here for the growing significance of biogas in the US). When the plant’s turbine is not run by solar power, it runs on biogas.
Waste heat from the turbine can be reclaimed to keep the biogas digesters running at an optimal temperature. The arrangement also benefits the farm, which gets an environmentally and financially sound way to dispose of its manure.
The farm could also benefit by reclaiming waste heat from the Tulip for operations such as pasteurization.
That resolves a chunk of the energy storage issue right then and there without the need for expensive new battery technology. The microturbine is a true hybrid that can run on any locally available fuel. For local communities where biogas from manure, wastewater, food waste (including waste oil), or landfills are sufficient and reliable sources, that means 24/7 renewable energy.
As for the technology, the Tulip uses a quartz dome to focus solar energy from the heliostats, which are continuously adjusted to track optimal sunlight. The resulting blast of hot air goes to the turbine.
We were not permitted to get an up-close look at (or photos of) the really hot stuff ‘cuz those are trade secrets, but we can tell you that some tweaks for the Tulip include a new heliostat manufacturing process, a robotic system for keeping the heliostats clean on a commercial scale (the modular unit at Samar is cleaned by hand), and fine-tuning of the tracking system.
Hot Oil For Solar Power
The other Arava region CSP plant that we got to see first hand was built by the firm of Shikun & Binui near Kibbutz Yotvata. It features rows of mirrored parabolic troughs that focus solar energy, but instead of focusing on a single point in a tower the energy goes to a narrow pipe of oil running along the length of each trough.
As with the Samar facility, the mirrors closely track the sun for optimal efficiency.
Once heated, the oil (synthetic oil, by the way) in the pipes is used to generate steam for a steam turbine, and then it is recycled back to the troughs for reheating.
The heated oil can also be stored in order to provide for night-time electricity generation, as a low tech alternative to some of the high-tech energy storage solutions coming into use for photovoltaic and wind power plants. Molten salt is another option with good potential.
Also as with the Samar facility, the plant’s turbine could run on any other locally available fuel including biogas, which to our way of thinking puts the whole energy storage issue to rest at least on a local level.
In other words, if you look at the Tulip together with the parabolic trough facility, it’s clear that optimal CSP solutions can already be achieved in some regions, by taking nearby resources into account and forming partnerships that benefit both the owner of the CSP plant and local businesses that provide feedstock for biogas.
Looking about three years down the road, last week we also toured a demonstration photovoltaic project at nearby Kibbutz Ketura, where they are zeroing in on another technology (that’s a secret, too) for a planned utility scale plant, which will apparently put the energy storage question to rest once and for all.
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