Upgrading biogas derived from agricultural waste
Customer: Keithick Biogas Ltd - a joint venture between Iona Capital/SGN and Keithick Farms Ltd - with site development and management by Biogas Power Ltd.
Location: Coupar Angus, Perthshire, Scotland.
Purpose: biogas-to- biomethane upgrading for pipeline injection (gas-to- grid)
Order date: February 2014
Plant commissioned: January 2015
The project was the first in Scotland to inject upgraded biogas into the local gas natural gas network. As such it benefits both from the gate price at the point of entry to the grid, plus the available UK government incentive, in the form of the Renewable Heat Incentive (RHI).
The purpose-built facility is in a rural location, partly screened by forestry, within a large country estate devoted to mixed farming. The project benefitted from its location within 250 metres of the existing grid infrastructure.
The plant upgrades raw biogas produced in 3 digesters from over 36,000 tonnes per annum of whole crop rye, maize, sugar beet off-cuts, raw silage and chicken litter from local businesses. Biogas Power Ltd specialise in on- farm energy from waste and were instrumental in developing the specification in conjunction with Greenlane.
Greenlane supplied a complete biogas-to-biomethane upgrading system. The ‘Matai’ model selected for the project sits in the middle of the 6-model range of Greenlane upgraders. It uses proven water-wash technology and can process between 400 and 1200 cubic metres of biogas per hour. Like all such units supplied by Greenlane, it uses neither heat nor chemicals in the process, just water.
The wide operating range enables a customer to be producing biomethane efficiently from the earliest stages of production. Once at full capacity, plant availability exceeds 98%.
In addition, Greenlane supplied ancillary equipment including a propane enrichment system and a H2S filtration system.
The plant has been operating successfully and has the potential to produce up to 3 million cubic metres of biomethane annually for injection into the gas grid - equivalent to 31,500 MWh of renewable energy.
The contract includes a 5-year enhanced aftercare package that is providing comprehensive 24/7 cover for the upgrading system. This includes remote monitoring and management of the plant’s performance, further strengthened by having regularly scheduled site visits by a member of Greenlane’s own full- time UK-based service team.
The project specification and the biogas upgrading technology used in this project confirmed the importance of selecting the right size of upgrader for the amount of available feedstock. This enables the plant to operate at peak efficiency and supply the maximum commercial returns within the context of the regional grid demands.
The payback period for the investment required was shown to make a strong commercial case to proceed. A by-product of the process is the use of the residual contents of the digester (digestate) as a fertiliser - thus creating an excellent example of the closed-loop economy.
This type of technology is a recognised solution to the UK Government’s stated objectives in complying with both EU landfill targets and de-carbonising the UK gas market.