UK firm hails solar steam breakthrough

UK renewables specialist Lark Energy has been granted a UK patent for a solar thermal system that it claims could have a host of applications for power generation and desalination.

Dubbed ‘solar steam’, the technology works by focusing the sun’s rays through a Fresnel lens array onto a tube that contains water. The water is heated to create steam which can be used in industrial heating and cooling applications.

The angle of the lens array can be adjusted through a vertical axis to track the sun and is seated on a circular track that allows the array also to follow the sun’s progress horizontally across the sky.

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Larkfleet’s Simone Perini with the Solar Steam array

By tracking in both planes, the system maintains maximum levels of solar radiation concentrated on the tubes.

Lark Energy’s parent company, housing developer Larkfleet Group, has been testing a small-scale version of the device at at its offices in Lincolnshire since August 2015. 

Commenting on the development Simone Perini, renewable energy development engineer at Lark Energy, said: “Solar steam builds on existing ideas about using solar radiation to generate heat and takes them a step further.

“The initial development of the project is complete. We are now seeking to take this technology to a wider market where we believe it will have a positive impact on the generation of sustainable and renewable heat.”

Potential for renewable power generation using a solar steam array is greatest in sunny regions such as southern Europe and Asia. India alone has an estimated potential of between 700 and 2,100GW of capacity using a solar steam system.

The solar steam array can be used in desalination, the process of removing salt from water to make it potable. This is of particular value in coastal countries with water shortages like India.

The two main methods of desalination are reverse osmosis – forcing water through a membrane to collect contaminants – and multistage flash.

The multistage flash method uses heat to convert salt water into fresh water. ‘Flash’ refers to rapidly bringing the water to a boil multiple times or in stages. As the salt water enters each stage of the conversion unit it is subjected to externally supplied steam heat and pressure. During each stage, fresh water vapour forms and is collected.

“Solar steam used in the desalination process will have a lower environmental impact because it is renewable and sustainable way of delivering the steam needed in the Flash method,” said Perini.

Lark Energy is now seeking to deploy the technology internationally on a commercial basis. The company has filed an application for a patent in the European Union and in India.