Biogas and Biomethane production as a sustainable source of renewable energy from farms and wastewater treatment sludges is showing steady growth globally. Read on to learn more:
The global biomethane market is on a growth trajectory mainly due to the green gas characteristic of biomethane. Biomethane is produced by the natural breakdown of organic matter, which includes agricultural waste, green waste, household waste, food industry waste, wastewater treatment sludges and even industrial waste.
The process involves the disintegration of organic material in an anaerobic environment to produce biogas, which is further purified to produce biomethane.
A significant factor fuelling the growth of the biomethane market is the high potential usage of biomethane in the automotive and power generation sector.
The developed countries of the world are increasingly diversifying conventional energy production practices to include renewable sources for energy needs.
The climate change conference in Paris in 2015 has led many countries to include more renewables and cleaner fuels in their energy production strategies. In particular, the European countries have set targets to increase the share of renewable energy to 20% by 2020 and to increase it to 80% by 20250 in the energy mix.
Biogas from Livestock Operations
Biogas recovery systems at livestock operations can be used to produce renewable natural gas. Animal manure is collected and delivered to an anaerobic digester to stabilize and optimize methane production. The resulting biogas can be processed into rng and used to fuel natural gas vehicles. As of August 2017, there were about 250 anaerobic digester systems operating at commercial livestock farms in the united states. Most of these facilities use biogas for electricity generation. A few farms are using biogas to produce a transportation fuel, including Hilarides dairy in California and fair oaks dairy in Indiana. EPA’s Agstar database provides more information about the use of such systems in the united states.
Some dairy farms and livestock operations use anaerobic digesters to produce biogas from manure and used bedding material from their barns. Some livestock farmers cover their manure holding ponds (also called manure lagoons) to capture biogas that forms in the lagoons. The methane in the biogas can be burned to heat water and buildings and as fuel in diesel-engine generators to generate electricity for the farm. EIA estimates that in 2018, about 29 large dairies and livestock operations in the united states produced a total of about 266 million kWh (or 0. 3 billion kWh) of electricity from biogas.
Australian Biogas Including from Wastewater Treatment
While Australia currently does not have any upgrading plants, the production of biomethane can provide a huge boost to Australia’s nascent biogas industry. The main use of biogas in Australia is for electricity production, heat, and combined heat and power. Australia’s biogas sector has more than 240 anaerobic digestion (ad) plants, most of which are associated with landfill gas power units and municipal wastewater treatment. They also include:
- about 20 agricultural A plants, which use waste manure from piggeries
- about 18 industrial AD plants, use wastewater from red meat processing and rendering as feedstock for biogas production.
Biomethane (CH4) production from microalgal biomass is of interest because the efficiency of algal biomass production per hectare is estimated to be 5–30 times greater than that of the terrestrial crop plants (Sheehan et al. , 1998). Golueke and Oswald (1959) published one of the first feasibility studies using microalgae for ch4 production and concluded that the process was feasible (Golueke and Oswald, 1959). There are two well-established methods of ch4 production: (1) harvest of an algal polyculture from a wastewater treatment pond, or (2) axenic growth of specific algae at a bench-scale (Asinari di San Marzano et al. , 1982; yen and Brune, 2007).
The digestion process begins with bacterial hydrolysis of the algal biomass. Organic polymers, such as lipids, carbohydrates, and proteins, are first broken down into soluble derivatives, which are further fractionated into carbon dioxide, hydrogen, ammonia, and organic acids by acidogenic bacteria. Acetogenic bacteria then convert these resulting organic acids into acetic acid, along with additional ammonia, hydrogen, and carbon dioxide. Finally, methanogens convert these products to methane and carbon dioxide.
Sources of Biogas and Biomethane
Biogas is produced mainly from organic residues and it consists of 45 – 85 vol% methane and 25 – 50 vol% carbon dioxide. Like other renewable energy sources, biogas can contribute to the reduction of co2 emissions from different sectors, as it can be used as a transport fuel, to produce heat and power or as a raw material for further applications. The competitive advantage of biogas compared to other renewable sources is that it takes advantage of the existing infrastructure and can be stored, providing an alternative to intermittent generation from other sources, such as solar and wind, and ensuring the security of supply.
Renewable natural gas (RNG) is a pipeline-quality gas that is interchangeable with fossil natural gas but is produced from biogas and biomass feedstock sources. It can be used as a 100% substitute for or blended with conventional gas streams for use in vehicle engines. With an estimated resource potential of 4. 8 trillion cubic feet in the united states alone, or 20% of total us natural gas consumption, rng is a valuable complement to the diversity and security of the natural gas fuel supply.
How does biomethane compare to natural gas?
The bad news is that there’s a limited amount of biomethane from waste compared to existing energy and fuel use in California—and we shouldn’t encourage creating more waste than we already do. Meeting California’s diesel demand would require all of the potential sources of waste-based biomethane in the united states. And biomethane from waste in California could meet just 3 per cent of the state’s demand for natural gas. Increasing biomethane production will require the expansion of natural gas infrastructure and improvements in waste management.
The future of “green” mobility in our country is closely linked to the diffusion of natural gas and biomethane, which represent the “Italian way” to the decarbonisation of transport. Italy is a leader in Europe for automobiles circulating in CNG (compressed natural gas), a technology that breaks down particulates and nitrogen oxides and considerably reduces carbon dioxide emissions compared to traditional fuels such as diesel and petrol. Biomethane makes g-mobility renewable and even more green: this resource, which can be obtained from the organic fraction of municipal waste or from agricultural and agri-food wastes, emits almost zero levels of dust (as well as conventional natural gas) and it further reduces co2 compared to methane and traditional fuels. The emissions of a biomethane vehicle are comparable to those of an electric vehicle powered by wind power.
Biomethane’s emissions benefits depend on how it’s used
Capturing landfill gas or biogas for processing into biomethane suitable for vehicles has significant benefits. Reduces greenhouse gas (GHG) emissions: biomethane that is used as fuel in place of fossil fuels produces less GHG than the fuel it replaced. Unlike naturally occurring methane emissions, biomethane is converted to co2 during combustion. Renewable resource: biomethane is a renewable resource that can displace fossil fuels by 100%. Food security: biomethane does not compete with food production. Using natural gas and biomethane as low-carbon fuels addresses global warming, high oil prices and foreign oil dependence.
Biogas production by region and by feedstock type
Biogas is a mixture of methane, CO2 and small quantities of other gases produced by anaerobic digestion of organic matter in an oxygen-free environment. The precise composition of biogas depends on the type of feedstock and the production pathway; these include the following main technologies:
biodigesters: these are airtight systems (e. g. containers or tanks) in which organic material, diluted in water, is broken down by naturally occurring micro‑organisms. Contaminants and moisture are usually removed prior to the use of the biogas.
Landfill Gas Recovery Systems
The decomposition of municipal solid waste (MSW) under anaerobic conditions at landfill sites produces biogas. This can be captured using pipes and extraction wells along with compressors to induce flow to a central collection point.
There are two processes for biomethane production classified by the type of feedstock. Wet materials are suitable for anaerobic fermentation or biomethanisation, while dry materials are appropriate for the gasification process (Bordelanne et al., 2011). The biomethane production through the biogas production process is sensitive to conditions: ph, temperature, digester technologies, moisture content of feedstock and/or feedstock type including the type of bacteria.
Biogas technology is considered a mature technology for the treatment of slurries and feedstocks with less than 12% dry matter. Technologies such as dranco© and kompogas© are in operation for high dry solids feedstocks (30-‐45%). Digestion can take place at either mesophilic (35–40oC) or thermophilic (55–60oc) temperature ranges. Theoretically, thermophilic temperature ranges are more appropriate for biogas generation than mesophilic temperature ranges. But more energy must be input to raise the temperature to the higher temperature range (Murphy and Power, 2009).
UK Biogas installed power generation capacity 2010-2018
In the UK there was 617mw of installed biogas capacity in mid-2016, up 30% on the year, according to the Anaerobic Digestion and Bioresources Association (ADBA). Since then, the growth in capacity has stalled due to lower subsidies – cut partly as a result of concerns over competition between biogas and food crops on limited agricultural land (Germany has also seen cuts in subsidies, where they were particularly generous and the early biogas expansion rapid). Overall, generation from bioenergy contributed about 10% or 31twh of the UK’s total power in 2017 (out of a total renewable share of 29%), with biogas making up about a third of that. Imported biomass burnt at the giant Drax converted coal plant, made up most of the rest.
JC-Biomethane, LLC, was the first biogas plant in the pacific northwest to produce energy from the digestion of post-consumer commercial food waste. Through anaerobic digestion, the plant transforms a mix of organic waste into methane-rich biogas, which is then used to generate electricity. While most biogas facilities process a single feedstock, often municipal wastewater solids or dairy manure, JC-Biomethane co-digests post-consumer commercial food waste, as well as smaller volumes of dairy waste and fats, oils and greases from food processing plants and other sources.
The biogas fuels a 16-cylinder reciprocating engine, similar to a locomotive engine, that generates electricity. With a 1. 55 Megawatt capacity, the co-generation engine is expected to produce energy equivalent to what would be needed to power about half the homes in junction city for a year.
Biogas Consumption by End-Use 2018
Germany has a strong biogas industry with more than 10,000 biogas plants and is the EU leading country in terms of biomethane production. In 2016 there were 193 biomethane plants connected to the natural gas grid with a total estimated capacity of 1. 71 billion m3 of raw biogas processed [ 10 ]. It is an equivalent to about 940 million m3 of biomethane fed into the German gas grid. This contributes to about 12. 3% of the natural gas production or 1% of natural gas consumption in Germany.
Biomethane is a “green” gas derived from waste produced by the agri-food industry and restaurants, from farm and household waste, or from sewage sludge. This purified biogas possesses all of the properties of natural gas.
Biomethane is a source of renewable, clean alternative energy. It will help increase renewable energy sources to 23% of the total energy consumption, the goal that France has set for itself by the year 2020.
What are biogas and biomethane?
Renewable natural gas (RNG), also known as sustainable natural gas (SNG) or biomethane, is a biogas which has been upgraded to a quality similar to fossil natural gas and has a methane concentration of 90% or greater. Biogas is a gaseous form of methane obtained from biomass. By upgrading the quality to that of natural gas, it becomes possible to distribute the gas to customers via the existing gas grid within existing appliances. Renewable natural gas is a subset of synthetic natural gas or a substitute for natural gas (SNG).
Biomethane is pipeline-quality, high BTU methane derived from biogas and is an entirely renewable and readily available low-carbon alternative fuel that can be produced locally from organic waste. Chemically the same as conventional natural gas, biomethane is produced from the anaerobic digestion of organic matter such as animal manure, sewage, and municipal solid waste. After it is processed to the required standards of purity, biomethane becomes a renewable substitute for natural gas and, once compressed or liquefied, can be used to fuel natural gas vehicles.
There are multiple production pathways for biogas and biomethane
Biogas can be used in raw (without removal of co2) or in an upgraded form. The main function of upgrading biogas is the removal of co2 (to increase the energy content) and H2S (to reduce risk of corrosion). After upgrading, biogas becomes biomethane and possesses identical gas quality properties as natural gas, and can thus be used as a natural gas replacement.
The main pathways for biomethane utilization are as follows:
- production of heat and/or steam
- natural gas replacement (gas grid injection)
- compressed natural gas (CNG) and diesel replacement – ( bio-CNG for transport fuel usage).
A range of different feedstocks can be used to produce biogas and biomethane
Biomethane is often overlooked as a viable transport fuel option, yet when produced from wastes can provide a highly competitive, low-cost transport fuel alternative. Biomethane upgraded for use in vehicles can be produced for USD 0. 45–0. 55/lge from wastes, and USD 0. 65–0. 75/lge when maize silage is added. Large-scale production requires the purchase of feedstocks (e. G. Maize silage) for much of the throughput and is thus more expensive. The cost of upgrading to biomethane must be added to production costs for biogas, but this typically only accounts for 5–10% of production costs. The main constraint to the expanded use of biomethane is the need for a dedicated gas-based refuelling network and the relatively limited quantities of waste feedstocks relative to total transport demand.
These market mechanisms give producers the certainty of selling a certain amount of biogas and biomethane to a selected supplier at a previously fixed price and for a fixed term. These are the pillars of government support for the industry. These purchase tariffs are determined by the government, depending on several factors, such as the form of valorization used, the size of the unit and the nature of the feedstocks.
There are two types of fixed purchase tariffs for biomethane injected into natural gas networks.
Biogas: Most production today comes from crops and animal manure
This section is about the use of biogas in the industry for the purpose of energy creation (heat and electricity) and/or non-transport fuel that can be released back into the grid for general public use.
Biogas is produced via a process called anaerobic digestion (AD), which results in the production of numerous gases that can then be burnt to produce energy. Anaerobic digestion is the breakdown of various plant and animal materials (known as biomass) by bacteria in an oxygen-free environment. For example, the waste plant material is sealed in an airtight container, and then bacteria is added, which is encouraged to multiply and grow, releasing methane and other gases as the by-product of the process.
In addition, there are other by-products produced in the process which are rich in nutrients and can be used as fertiliser. The inputs in the process can be any number of biomass materials including any of the following: food waste, energy crops, crop residues, slurry and manure. In practice the process can take on waste from households, supermarkets and industry, therefore reducing the waste that goes to landfills.
Most of the biogas produced today goes to the power sector
Biomethane or biogas is the better fuel, not only because it is climate-friendly, this fuel is just as efficient as natural gas. By removing co², biogas is identical in its properties to natural gas and would therefore be the better alternative to any other form of fuel in the car and truck sector, but also in public transport. In addition, the existing technology can be converted quickly and the overexploitation of mineral resources for batteries would be massively reduced. Vehicles powered by biogas also reduce the emission of climate-damaging greenhouse gases by 65%. One could quickly and easily produce enough biomethane today to convert all traffic to the environmentally friendly form of fuel.
At present, most biomethane (renewable gas) generation/production is through the process of upgrading biogas (comprised of around 60% methane (ch₄) and 40% carbon dioxide (co₂)). Biogas is produced through the process of anaerobic digestion of organic materials, such as agricultural and food waste. Biomethane can be used as a direct substitute for natural gas and used as a fuel in applications such as heating, transport and electricity generation since it has the same properties as natural gas – achieving methane (ch₄) content levels greater than 96%.
Conclusion – Biogas and Biomethane Renewable Energy from Farms and Wastewater Treatment
Modern societies and economies produce increasing amounts of organic waste that can be used to produce clean sources of energy, with multiple potential benefits for sustainable development. Biogas and biomethane are different products with different applications, but they both originate from a range of organic feedstocks whose potential is underutilised today. The production and use of these gases embody the idea of a more circular economy, bringing benefits from reduced emissions, improved waste management and greater resource efficiency. Biogas and biomethane also provide a way to integrate rural communities and industries into the transformation of the energy sector.
Back in 2015, in the time in the UK when we first wrote about biomethane production, we were very optimistic that the level of activity seen that year would continue in the UK. There had been a very rapid rise in biomethane production, in the 18 months prior to October 2015. But, that year proved to be a peak year for growth in UK biomethane production facility output.
Anyone who was taking an interest in the anaerobic digestion industry and the renewable energy scene would have seen a rash of announcements of new AD plants which were from the outset equipped with biogas upgrade equipment. There were also, no doubt, some existing ad facilities where biogas upgrading equipment was added to some traditional electrical power generation plants to allow them to move over to biomethane production.
Fortunately, the surprising drop off in UK activity since 2015 has now been replaced by increased biogas and biomethane production in many countries, and the global prospects for large AD, biogas and biomethane production industry growth are now good.
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