Inside the world’s largest single-unit solar power plant

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Shams 1 is the largest single-unit solar power plant in the world — with 768 parabolic trough collectors tracking the sun.

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I’m in Abu Dhabi this week for the 1st ever Abu Dhabi Sustainability Week, including the 6th annual World Future Energy Summit. Alongside of that, Masdar Corporation provided me (and a few others) with a tour of Shams 1, and it will also provide use with a tour of Masdar City. This post is part of a series on these events and on Masdar Corporation itself that Marika and I will be writing throughout this week and probably next.

This first post goes into more depth than our November piece on Shams 1, but that initial piece is also worth reading for some added context and info, so check it out: Largest Solar Power Plant In World Nears Completion In Abu Dhabi.

Most notably, as indicated in the title, Shams 1 is the largest single-unit solar power plant in the world — in total, it has 100 MW of capacity. It is a concentrated solar power (CSP) plant, but it is a bit unique. Very simply, here’s how the power plant works: 768 parabolic trough collectors track the sun from sunrise to sunset and use parabolic mirrors to focus the energy of the sun on a central tube containing oil. The concentrated heat is then passed through the system until it is used to boil water and produce steam, which drives a conventional turbine that generates electricity. Additionally, a middle step is the use of natural gas to “superheat” the water. Project managers informed us that this accounts for about 20% of the heat.

Theoretically, natural gas could be used to produce all of the electricity if desired or if power was needed while the sun wasn’t shining. However, barring unforeseen needs, that is not how the power plant is intended to run. The total natural gas power capacity of the plant, if it were to run in this way, is 50 MW.

Electricity from the power plant is competitively sold at market price to the grid. It is projected to reduce CO2 emissions 175,000 tons/year, which would be equal to planting 1.5 million trees or taking 15,000 Abu Dhabi cars off the street, according to Yousif Al Ali, the General Manager of Shams Power Company.

The power plant includes 258,048 parabolic trough mirrors on 628,000 square meters, or about the same area as 285 football fields. Another interesting side note is that the water used for the system is reused (i.e. it is a closed loop system).

Why CSP?

There are a few key reasons why Masdar Clean Energy went with CSP for this project. For one, the system is much more similar to conventional power plants than solar PV. As Yousif Al Ali (who worked in conventional energy industries for years) stated, it’s “based on an established system, that everyone trusts.” Everyone, in that sentence, means people within the utility and electricity generation industry. In Abu Dhabi, as everywhere, such people are more interested in keeping their professional paradigm the same, keeping things essentially the way they are, so a system quite similar to a conventional power plant was easier to “sell” to other relevant players. This is not the first time I’ve run across such statements, and it is one clear reason why many utilities are more opposed to decentralized solar power on rooftops than large CSP power plants like Shams 1.

Another key reason why this power plant was CSP rather than PV was cost. A couple of years ago, CSP was more cost competitive than PV (“slightly cheaper,” as Shams Power Company Process Engineer Abdulaziz Al Obaidli told me in an interview). That was before the price of solar dropped a tremendous amount. Since then, the solar market has turned 180 degrees. Now, Yousif Al Ali and Abulaziz Obaidli, forced (by me) to provide their best guess as to what Abu Dhabi’s renewable energy split will be in 2020 (when it is supposed to have 7% of its energy coming from renewable sources) both projected that most of Abu Dhabi’s renewable energy will be from solar PV. However, answering my questions in separate interviews, they also both indicated that they thought CSP would provide a good portion of the renewable energy mix. And Abulaziz Obaidli, working on his Phd at the moment, is actually focusing on some ways to improve the efficiency and cost-effectiveness of CSP power plants like Shams 1.

Why the Location?

Shams 1 is located about two hours from the city of Abu Dhabi*, quite far. It is “almost in the middle of the desert,” as Yousif Al Ali or Masdar Clean Energy Director Bader Saeed Al Lamki** noted. So, many of us on the trip were wondering, “why this location?”

The location of Shams 1 was picked due to several factors. For one, there was less of a problem with dust and aerosols accumulating on the mirrors than closer to the city (which is located on the coast). Humidity, wind, and, of course, automobile traffic play into that.

Additionally, there was already a gas line nearby — making the cost of bringing in the natural gas much lower — and the location was close to the grid. Solar irradiance is also very good there, naturally.

Energy Subsisides & Distortion

One last issue, which I intend to delve into in more detail in a future post, is subsidies. Every energy source is subsidized. A huge variety of factors change “true market prices,” and to create such a price (one without any distortion) is practically impossible… and hardly ever attempted. In other words, our general way of discussing price per kWh is a very simplified way of discussing price that always makes assumptions about which subsidies or distortions we include and which we don’t. And this is not just coming from me, a cleantech enthusiast trying to help protect humanity from itself — this was discussed a bit by Yousif Al Ali, a former oil industry employee who didn’t seem to hold any grudge against the industry. The point of all this? What competes best on the market will win, but we choose if we want to distort the market for technologies that ruin our water, air, and climate; or if we want to do so for cleaner technologies.

This article was originally posted on Cleantechnica. Re-posted with permission.

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