Generator will help Masdar solar plant

Natural gas backup will assure a steady power output regardless of performance variations.

Haze, dust and humidity will reduce power production at the Shams 1 solar thermal plant in Madinat Zayed.

Masdar, the Abu Dhabi renewable energy firm, expects its signature solar power plant in Al Gharbia to operate at a minimum of 60 per cent capacity, in part with the help of a natural gas generator, the firm's chief executive says. The Shams 1 solar thermal plant at Madinat Zayed, soon to be the world's largest, will have the capacity to produce 100 megawatts of electricity from the heat of the sun, and is planned as a key link in Abu Dhabi's ambition to produce 7 per cent of its energy from renewables by 2020.

Like all power stations, however, Shams 1 will rarely reach its potential capacity: haze, dust and humidity will all obscure the sun's rays and reduce power production, said Dr Sultan al Jaber, the chief executive of Masdar. "The plant is 100mw and, depending on the efficiency of the technology, based on the humidity and the dust and the other outside factors, the objective was to produce not less than 60 per cent output," Dr al Jaber said.

Conservative forecasts by the Abu Dhabi Water and Electricity Authority (ADWEA) show the plant will guarantee at least 50mw to the grid. The reduced capacity factor reflected a problem that faced all energy planners, especially with plants that relied on sunlight or wind, said Robert Bryniak, the chief executive of Golden Sands Consulting, a UAE power consultancy. "The challenge with renewables has always been to get a steady output from the process," he said. "That's a pretty reasonable figure."

At a project of such unprecedented scale, it made sense to include a natural gas backup, he said. "We're talking about something that doesn't have a 20 to 30-year operating history," he said. "You do need something to help stabilise your power output: if you have several sources going into the grid system, it's not a big deal because they iron each other out." Dr al Jaber said the plant would be equipped with what he called a "small, insignificant" gas generator that would allow it to maintain the same output throughout the day, regardless of clouds, dust or other uncontrollable factors. The plant would not include a thermal storage facility to allow it to produce power after the sun set, he said.

Unlike photovoltaic solar panels, which produce electricity directly from the sun's rays, a solar thermal plant concentrates the heat of the sun and uses it to produce steam, which in turn runs a conventional electric generator. The design is easily paired with fossil fuels in hybrid designs that are already operating in Europe and the US, and are planned for Egypt and Algeria. Masdar would award a contract to build, own and operate the plant in the third quarter of this year, Dr al Jaber said. "We are still going ahead as per the plan."

In May, a senior project manager at the company, Olaf Goebal, told Reuters the plant would cost between US$520 million (Dh1.9 billion) and $550m, a saving of $105m since last autumn. In late April, Masdar awarded a contract to MAN Turbo, a German engineering firm, to supply a 125mw steam turbine for the project. The Shams 1 project will be followed by a series of solar thermal plants of similar size, which government planners hope will become the most important contributor to Abu Dhabi's generation of green energy.