Renewable gases, including biogas and biomethane, will be central to achieve carbon-neutrality by 2050 and help the EU become less dependent in external energy supplies.
Turning molecules into energy
Biogas is produced from the decomposition of organic materials. These residues are placed in a biogas digester in the absence of oxygen. With the help of a range of bacteria, organic matter breaks down, releasing a blend of gases: 45 – 85 vol% methane (CH4) and 25 – 50 vol% carbon dioxide (CO2). The output is a renewable gas which can be used for multiple applications.
If we upgrade biogas, we obtain biomethane. This purified form of raw biogas can be used as a natural gas substitute: CO2, H2O, H2S and other impurities are removed during biomethane production, leaving a high-caloric, pure gas.
Affordable, sustainable and secure energy for Europe
Biogas and biomethane are renewable gases which help abate emissions across the whole value chain. Their use is essential if we are to accelerate the reduction of GHG emissions in multiple sectors, including buildings, industry, transport and agriculture.
The deployment of biomethane to replace fossil fuels does not require the investment of additional resources to develop new infrastructure. The existing gas infrastructure is biomethane-ready. This is key to ramping up decarbonisation and providing affordable renewable energy for consumers.
In addition, biomethane can be easily stored and produced at a constant pace, helping balance energy supply from intermittent energy sources of renewable origin, such as solar or wind. It can also be traded and produced within Europe, ensuring the EU’s security of supply, and avoiding dependence on external providers.
Biogas and biomethane are already available and they are also cost-competitive, if we consider all positive externalities generated by the production of these renewable gases. Europe is the largest producer of biogas and biomethane in the world today, and it will be essential to scale up production of these renewable gases in order to meet renewable energy demand by 2030 and achieve climate targets in 2050.
Preventing GHG emissions
Biogas and biomethane prevent emissions across the whole value chain, with a three-fold emissions mitigation effect. Firstly, they avoid emissions that would otherwise occur naturally: organic residues are taken to the controlled environment of biogas plants, preventing the emissions produced by the decomposition of the organic matter from being released into the atmosphere. Secondly, the biogas and biomethane produced displace fossil fuels as energy sources. Thirdly, the use of the digestate obtained in the biogas production process as biofertiliser helps return organic carbon back into the soil and reduces demand for the carbon-intensive production of mineral fertilisers.
Renewable heat and power
Combined heat and power engines (CHP) are a common valorisation route for biogas in Europe. The idea behind CHP is that the co-generation of electrical and thermal energy is more efficient than generating them separately. Depending on the design of the biogas plants, part of the heat from the CHP may be used to support the plant’s fermentation process – for example, if the biogas reactors require heat to maintain the correct temperature. The electricity produced is mainly fed into the electricity grid, while any surplus heat is available for local heating applications.
Clean transport
The latest studies show that biomethane is an effective way to abate GHG emissions from transport, which represent 25% of the total emissions in the EU.[1] Biomethane is used as a biofuel in the form of a CNG or LNG substitute, called bio-CNG or bio-LNG. Biomethane in transport is a high performer in terms of the reduction of GHG emissions, if we consider the full carbon footprint of the vehicles (Well-to-Wheel). Depending on the feedstock used, biomethane can have even negative emissions, meaning that CO2 is actually removed from the atmosphere. Liquefied biomethane can be used, for example, in heavy-duty road transport and the maritime sector, both of which are difficult to electrify.
Waste recycling
Biogas and biomethane are generated from different types of organic residues, turning waste into a valuable resource, which is the core principle of an efficient circular economy. Food waste or wastewater can be recovered from our cities and used to produce renewable energy, which helps develop a local bioeconomy. In the countryside, residues from animal farming or biomass from agriculture can be optimised and converted into energy, while digestate can be used as an organic fertiliser. This creates additional business models in the farming sector, making it more cost competitive, and promotes sustainable farming.
Agroecological transition
In many rural areas, agriculture is one of the main economic activities. Agriculture is also a major contributor to the production of renewable energy, including biogas. Combining agricultural activities with renewable energy production through biogas has multiple benefits: it helps farmers to manage their waste and residues efficiently, it reduces emissions from agriculture and it improves soil quality and biodiversity in farmlands.
In these healthy ecosystems, plants absorb carbon dioxide from the atmosphere acting as carbon sinks, digestate used as organic fertilizer returns nutrients into the soil; methane emissions from livestock are taken into the controlled environment of a biogas plant, instead of being released into the atmosphere; the use of sequential crops protects the soil and increases biodiversity.
The promotion of sustainable and efficient agricultural practices is an important driver of rural development by making agriculture more sustainable and cost competitive.
Closing the carbon loop
Carbon dioxide is a by-product of the purification of biogas to biomethane. The carbon dioxide stream can be valorised in the food industry or can be used to maximize photosynthesis potential in greenhouses. This is the last step of the so called ‘short carbon cycle’, a process which starts with the use of the carbon contained in organic residues to produce biogas, which is partly composed of carbon molecules. The ‘short carbon cycle’ continues with the re-use of the carbon contained in the digestate: spreading the digestate as organic fertiliser puts the carbon back into the soil. Completing the whole carbon cycle by valorising the carbon dioxide after producing biomethane ensures the removal of the carbon from the atmosphere.
[1] European Union, Renewable energy in EU agriculture EPRS | European Parliamentary Research Service
[2] Eurostat – SHARES (Renewables)
[3] Panagos et al. have assessed the beneficial effect of cover crops in preventing soil erosion. They conclude that extending cover crops to 35% of European arable land would reduce the risk of soil erosion by 40%.
Panagos et al. (2015), Estimating the soil erosion cover-management factor at the European scale
[4] Navigant estimates that with the help of sequential crops, European biomethane production could reach 41 bcm.
Definitions
Biogas
The primary product of AD is a methane-rich renewable gas composed of 45 – 85 vol% methane and 25 – 50 vol% carbon dioxide.
Digestate
Remaining part of organic matter treated by AD, rich in nutrients and nitrogen, commonly used as an organic fertilizer in agriculture.
Syngas
The primary product of gasification is a mixture of carbon monoxide and hydrogen, with traces of methane and carbon dioxide. It may be used directly for electricity generation, or further transformed to increase its share of methane.
Biomethanation
Is the chemical process of creating methane by combining gaseous carbon oxides with hydrogen.
Biomethane
When carbon dioxide and trace gases in biogas are removed, a methane rich renewable natural gas substitute is left in the form of biomethane. Biomethane can be injected into the gas grid, used as a vehicle fuel or used for combined heat and electricity generation.
Sequential cropping
Is an agricultural practice where two different crops are grown in sequence on a same piece of land in a same farming year. Usually, a second crop is planted after a preceding main crop has been harvested, without competition of land for food and feed, enabling the available natural resources to be preserved and more efficiently utilized.