Translated as ‘mirror’ in Arabic, Miraah is a proposed 1,021MW solar thermal facility to be located in South Oman, and expected to be one of the world’s biggest solar plants. Construction of the plant commenced in October 2015, while operations are scheduled to begin in August 2017.
The thermal energy produced by the facility will produce steam that will be used for thermal enhanced oil recovery (EOR) to extract heavy and viscous oil at the Amal oilfield. Thermal EOR, which is touted to enhance well productivity by up to 300%, uses high-pressure steam, which is injected into the oilfield reservoirs to make the oil easier to be pumped to the surface.
GlassPoint Solar has been contracted to construct the new solar thermal plant by Petroleum Development Oman (PDO), a joint venture (JV) between the Government of Oman, Shell, Total and Partex.
The project builds from the success of the existing 7MW pilot plant at Amal that was commissioned in February 2013 and has an output of 50t of steam a day. The pilot plant will complement the Miraah facility, when the latter comes online.
The project will use GlassPoint Solar’s enclosed trough technology, a concentrating solar power (CSP) technology that uses large, curved mirrors to focus sunlight on a boiler tube containing water. The harnessed energy boils the water in the once-through steam generators (OTSG) to produce steam that is fed to multiple steam injector wells within the oilfield.
The mirrors will be enclosed with a glasshouse, protecting them from wind, sand and dust storms. The glasshouse will further be equipped with automatic washing facilities, which are capable of recycling the majority of the water used.
The innovative glasshouse further enables the use of thin and lightweight components, significantly reducing the material usage when compared to exposed solar thermal systems.
The mirrors will be suspended from the glasshouse ceiling and controlled by small, inexpensive positioning systems and motors. The OTSG will have a fully-automated control system that enables remote operations from a computer and uses the same boiler tubes, sensors, pumps and controls used by gas-fired steam generators.
The project site will cover an area of approximately 3km² (741 acres), of which the solar plant will occupy less than 2km².
It will be equipped with 36 glasshouse modules, which will be constructed and commissioned successively in groups of four. Each glasshouse will be capable of generating 85MmBTU/h (28MWt) of steam at peak capacity.
The glasshouse roof is approximately 6m above ground level, reducing the soiling rate by 50% compared to the use of typical exposed solar designs where the mirrors are placed around 1m above ground.
The facility will generate approximately 6,000t of solar steam a day. The use of solar energy will save approximately 5.6 trillion British thermal units (BTUs) of natural gas a year, which is sufficient to provide residential electricity to approximately 209,000 people in Oman. It will enable the country to redirect the gas saved from the project to meet the growing industrial demand and enable the country to offset 300,000t of carbon dioxide emissions a year.
The project will also demonstrate the use of solar for the oil industry on a commercial-scale.
The natural gas used for oil production in Oman currently accounts for more than 20% of the nation’s total gas consumption, more gas is used to aid oil production than for electricity generation.
Use of solar EOR technology could reduce gas consumed at the oilfield by up to 80%, redirecting the gas to the export market or for higher value uses, such as industrial development.