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What is Biogas and why is it important?

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What is Biogas and why is it important?


What is biogas?


Biogas is an environmentally-friendly, renewable energy source. It’s produced when organic matter, such as food or animal waste, is broken down by microorganisms in the absence of oxygen, in a process called anaerobic digestion. For this to take place, the waste material needs to be enclosed in an environment where there is no oxygen. It can occur naturally or as part of an industrial process to intentionally create biogas as a fuel. Organic matter fed into this process range from livestock waste, crop leftovers, waste water and food waste. The brilliance of Biogas is that it is generated from waste materials, which would have otherwise been discarded of, and the by-products of the process also have value. As the digester feed stock breaks down, raw biogas is created with a typical composition of Methane (50-75%), Carbon Dioxide (25-50%), Nitrogen (0-10%), Hydrogen (0-1%), Hydrogen Sulfide (0.1-0.5%).

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Why is Biogas important?

The energy demand of our planet is ever increasing and consumption has never been higher, whilst are still at the infancy stages of a global movement towards a more sustainable society – Biogas has its role to play in supporting this transition as we look towards the future with less reliance on fossil fuels, scaling up use of renewable energy sources and decarbonising our planet.

How is the Biogas and digestion products used?

This raw biogas produced in this digestion process is first treated to turn it into "clean biogas". This involves removal of any sulphur & siloxanes – The resultant clean biogas has a multitude of uses:

  • Biogas CHP (Combined Heat & Power) Engines – These engines provide both heating and electricity, the dual output reduces reliance on the national energy grid for the end user, reducing power bills.

  • Biomethane Fuel – Raw Biogas is refined further by removing the Carbon Dioxide, which has a number of exciting applications with huge potential for mass adoption:
    - Liquefied Biomethane can be distributed for use as fuel in vehicles
    - Biomethane Gas can be directly injected into the national grid, supplementing the current natural gas supply

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What about the waste product leftover from digestion?

One of the reasons why Biogas has a great future is due to the full circle zero waste in the process.

The two main waste products leftover are:

  • Digested feedstock – As the animal waste/food crops etc. break down and generate biogas, the solid is left behind. This nutrient rich digestate can be used directly as an organic fertiliser for farming as the breakdown process will neutralise any pathogens contained in the feedstock

  • Co2 – When Biogas is upgraded to Biomethane the Co2 is removed from the gas mixture, this can be used either for valorisation in the food & drinks industry, or to maximise photosynthesis in greenhouse plant growing

Both of these uses ensure that we have a sustainable cycle of renewable energy. The industry has seen continual growth over the last decade and we expect this to accelerate as worldwide governments drive for cleaner energy.

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The Howden Screw Compressor

Howden have supplied multiple screw compressors to a number of key Biogas applications throughout Europe & North America, at the heart of enabling our customer’s vital biogas process.

Our screw compressors are recognised around the world for their unmatched reliability, able to handle the most demanding of biogas applications and our large range of compressors is well suited to handle increasing pressure and capacity requirements across the industry into the future.  

From our depth of experience from Industrial Refrigeration to off shore Oil & Gas, Howden has the necessary expertise provide reliable and trustworthy compressors for your vital processes.

Bitesize Biogas facts*

Biogas is a gas of many names

Biogas is most commonly also known as biomethane. It’s also sometimes called marsh gas, sewer gas, compost gas and swamp gas in the US. Biogas is a naturally occurring and renewable source of energy, resulting from the breakdown of organic matter. Biogas is not to be confused with ‘natural’ gas, which is a non-renewable source of power.

In the UK there are 118 biogas plants currently in operation, while the US has over 2,200 sites producing biogas

The first UK biogas plant was built in 2011, with the introduction of the government’s Renewable Heat Incentive scheme. Growth saw its first peak in 2016 when 33 new plants were built, according to the Anaerobic Digestion and Bioresources Association. In 2020, a Somerset dairy farm owned by Biocow was the first to plug its biogas production directly into the national transmission system.

The US has over 2,200 operational sites producing biogas in all 50 states – 250 anaerobic digesters on farms; 1,269 water resource recovery facilities using an anaerobic digester; 66 stand-alone systems that digest food waste; and, 652 landfill gas projects – according to the American Biogas Council.

Christmas food waste is enough to heat 25,000 homes with biogas

WRAP estimates that UK households, hospitality and food service, food manufacture, retail and wholesale sectors produce around 10 million tonnes of food waste per year. If this was all treated through anaerobic digestion, the industry could generate 11 TWh of biogas – enough to heat 830,000 homes – and cut emissions by 8.8 million tonnes of CO2 equivalent, or 2% of the UK’s annual emissions.

In the Christmas season alone, we waste 270,000 tonnes of food in the UK. Our leftover mince pies, roast veg and Christmas pudding would generate 300 GWh of biogas – enough to heat 25,000 homes – and cut carbon dioxide emissions by 236,000 tonnes! Now that’s food for thought*.

Today China leads the world in the use of biogas

China has the largest number of biogas plants, with an estimated 50 million households using biogas. These are mostly in rural areas and small-scale home and village plants. The torch at the 2008 Beijing Olympics was fuelled with biogas!



Article Date

Friday, 28 May 2021



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