A company which has developed a unique anaerobic digestion system is poised for growth after securing sales of �18m.

A company which has developed a unique anaerobic digestion system is poised for growth after securing sales of �18m.

Add Energy, based at the Hethel Engineering Centre to the south of Norwich, has designed an anaerobic digestion (AD) system specifically for farms, turning cattle slurry or plant matter into valuable electricity.

Unlike its main competitors, Add Energy's systems are built underground and sealed, helping avoid planning obstacles.

The process is also thermophilic - carried out at higher temperatures of up to 55C - making it far faster than other AD systems, taking 10 to 14 days compared to 45 days in some rival systems.

Boosted by the government's feed-in tariffs - which guarantee low carbon energy producers a rate of payment per unit - the company has secured 10 contracts in the South West, worth �18m.

And the firm is currently recruiting a salesman and project manager to market the system to farmers in East Anglia, particularly producers of sugar beet which can be used as a fuel.

The systems, which produce between 100 kilowatts and one megawatt of electricity which can be used on the farm or exported to the national grid, can pay with themselves within three or four years and offer farmers a six-figure annual income.

The company, which has been in operation for about a year, employs five, which is expected to rise to eight or nine within six months.

The first of the 10 systems being installed in the South West is due to be completed within the coming two months, with the rest at various stages of progress.

AD systems use microorganisms to digest waste material and produce gas which can be used to generate electricity.