Methane could mean money for dairy units

Dairy farmers in the north west are being urged to consider the viability of methane collection as an additional source of income.

Cumbria-based feed consultant Jerry Trowbridge had his eyes opened to the idea while on a tour of dairy units in the USA.

On a trip to a 2400-cow herd in Minnesota he discovered that the slurry was earning almost as much as the milk after the farmer started extracting methane gas from the fermented muck.

Mr Trowbridge, who is considering taking a party of UK dairy farmers to the USA to show them the project, says experts have told him that any dairy farm milking 500 cows or more should be big enough to make a similar scheme viable.

Although there has been intermittent UK research into methane captured from pig slurry, Mr Trowbridge said the US venture based on cow slurry was actually “up and running” and selling methane as bottled gas.

“The slurry is pumped into a sealed tank where it’s heated using a heat capture system from the parlour.

The methane given off is collected, cleaned and bottled.

“There are now 11 other farmers near the Minnesota unit who are installing similar systems, which justifies the construction of a pipeline to pump the gas direct to the customer,” said Mr Trowbridge.

Each cow is producing 110cu ft of methane per head per day – but that is only part of the story.

The process, which involves two stages, kills both the aerobic (requiring oxygen to survive) and the anaerobic (not requiring oxygen) bugs.

The slurry is then dried at a low cost to produce an inert and hygienic bedding material.

“It’s actually a very springy and soft material that’s ideal for cow bedding, and they’ve even found a use for the waste water from the slurry.

This is piped away and used for irrigation of organic crops.”

Mr Trowbridge says the system could appeal to dairy farmers in the UK if they have enough cows.

“The whole process ticks every environmental box.

It’s producing a food source, an energy source, a bedding material and a supply of water for irrigation.”

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