Online shop

Green Gas Certification

Green Gas Certification

Apsley Farms is a trading name of a group of companies, one of these is Yelspa Ltd, which owns and runs a 6.5 MWHe equivalent biodigester plant set in the heart of southern England.

Our biodigester is made up of 1.1 MWH of electricity production made from biogas. We also have 5.5 MWH electrical equivalent of biomethane injection into the grid.

Our anaerobic digesters are fed on purely arable crops, whole crop maize, rye, grass, oats, and some grain. This makes our feedstock process very simple to manage as we are constantly buying ahead and not having to worry about waste contracts and whether the waste will turn up on the day.

The Biogas Plant

Our biogas plant has a long retention time of 150 days, making it one of the more efficient in the UK helping us to extract as much of the energy out of our feedstock as possible, releasing a reduced amount of CO2 into the atmosphere once it has been separated into its liquid and solid form (digestate).

Once the biogas has been separated into its two component gases (CH4 and CO2) by using a membrane plant, the two streams of gases are at 97% of quality each.

The final processing of our CO2 into a food and beverage grade liquid takes place using specialist equipment. That enables to retun all unwanted gases, including any contaminant methane (CH4), to the digesters.

We produce around 9,000 tons of high quality food-grade CO2 a year, which we transport to customers all over the UK using our own fleet of tankers. Read more about our bulk CO2 supplies below.

Our current methane slippage is less than 0.2 percent.

Buy CO2 in bulk


We have been selling green gas certificates from our biomethane production for the last 8 years to end users and to traders across Europe, enabling a certified renewable CH4 market to grow.

We hope that these certificate of origin will enable a no subsidy biogas sector to thrive in years to come as confidence grows in this industry.

For the past 3 years we have achieved DENA accreditation.

find out more about our processes

Gigawatt Hours

We currently produce 104 GWH per annum of green gas certificates and the table, right, shows what is available in GWH per quarter.