In essence, vast quantities of ****** waste are mixed with lots of grass in a cylindrical tower - "basically a 3,000 tonne cow's stomach," says Mr Hart.
Bacteria then breaks down the mixture, producing methane, which is siphoned off, cleaned and filtered.
Mr Hart has bet heavily on the success of his new biogas plant
This gas is then used to power what is effectively a £200,000 Mercedes truck engine, which in turn powers a generator, electricity from which is fed into the National Grid.
A by-product of the process is large quantities of fertiliser that remain in the tower once the bacteria have worked their magic.
The heat generated by the process is also captured and used for central heating at the **** house. It is, then, in renewable-energy speak, an efficient 'closed-loop' system.
And the benefits to the **** are both numerous and substantial.
But it's not just Mr Hart's business that benefits from the plant.
Methane is about 20 times worse than carbon dioxide in trapping heat in the atmosphere and so is widely recognised as one of the more potent greenhouse gases.
By capturing the methane produced by the waste generated by his 4,000 pigs, 100 cows and 100,000 chickens, Mr Hart expects to reduce his equivalent carbon footprint by about 10,000 tonnes a year. That's the equivalent of almost 9,000 return flights from London to New York.
He is also using far less fertiliser, which can be fairly carbon intensive to manufacture.
