Renewable Natural Gas (RNG), also known as Sustainable Natural Gas (SNG) or biomethane, is a biogas which has been upgraded to a higher carbon content and has a methane concentration of 90% or greater. A biogas is a gaseous form of methane obtained from biomass. By upgrading the quality of natural gas, it becomes possible to distribute to customers through the existing gas grid within existing appliances. Renewable natural gas is a subset of synthetic natural gas or natural gas substitutes (SNG). Renewable natural gas can be produced economically and distributed through the existing gas grid, making it an attractive means of supplying existing facilities with renewable energy and renewable energy, while requiring no extra capital outlay of the customer. Renewable natural gas can be converted into natural gas (LNG) for direct use as fuel in transport sector. LNG would be fetch good price equivalent to gasoline or diesel as it can replace these fuels in the transport sector. The existing gas network allows the distribution of energy over vast distances and a minimal cost in energy. Existing networks would allow biogas to be sourced from remote markets that are rich in low-cost biomass (Russia or Scandinavia for example). The UK National Grid believes that at least 15% of all gas is consumed by such foods, food waste, such as food and food waste. In the US, analysis conducted in 2011 by the Gas Technology Institute in the United States of America. Btu annually, being able to meet the requirements of 50% of American homes. In combination with power-to-gas, the carbon dioxide and carbon monoxide fraction of biogas is converted to methane using electrolyzed hydrogen, the renewable gas potential of biogas is approximately doubled. Many ways of methanizing carbon dioxide / monoxide and hydrogen exist, including biomethanation, the sabatier process and a new electrochemical process in the United States currently undergoing trials. In combination with power-to-gas, the carbon dioxide and carbon monoxide fraction of biogas is converted to methane using electrolyzed hydrogen, the renewable gas potential of biogas is approximately doubled. Many ways of methanizing carbon dioxide / monoxide and hydrogen exist, including biomethanation, the sabatier process and a new electrochemical process in the United States currently undergoing trials. In combination with power-to-gas, the carbon dioxide and carbon monoxide fraction of biogas is converted to methane using electrolyzed hydrogen, the renewable gas potential of biogas is approximately doubled. Many ways of methanizing carbon dioxide / monoxide and hydrogen exist, including biomethanation, the sabatier process and a new electrochemical process in the United States currently undergoing trials.

A biomass to SNG efficiency of 70% can be achieved. Costs are minimized by maximizing production scale and by locating anaerobic digestion plant for transport links (eg a port or river) for the chosen source of biomass. The existing gas storage infrastructure would allow the plant to be used to reduce the costs of production. Renewable gas can be produced through three main processes

Gothenburg Energi opened the first demonstration for large scale production of bio-SNG through gasification of forest residues in Gothenburg, Sweden within the GoBiGas project. The plant has the capacity to produce 20 megawatts-worth of bioSNG from about 30 MW-worth of biomass, with a conversion efficiency of 65%. From December 2014 the bioSNG plant was fully operational and supplied to the Swedish natural gas grid, reaching the demand for a methane content of over 95%. The plant was permanently closed due to economic problems in April 2018. Göteborg Energi had invested 175 million euro in the plant and intensive efforts to reduce the price of the plant. It can be noted that the plant was a technical success, and performed as intended. HOWEVER, natural gas is currently at a very low price given market conditions globally. It is expected the plant is to re-emerge around 2030 when economic conditions may be more favorable, with the possibility of a higher carbon price. SNG is of particular interest in countries with extensive natural gas distribution networks. Core advantages of SNG include compatibility with existing natural gas infrastructure, higher efficiency than biofuel production systems and more. SNG production from woody biomass, based on the import of feedstocks from abroad. Renewable natural gas plants based on two categories, one being allothermal, which has the energy provided by a source outside of the gasifier. One example is the double-chambered fluidized bed gasifiers of a separate combustion and gasification chambers. Autothermal systems generate the heat within the gasifier, but require the use of pure oxygen to avoid nitrogen dilution. In the UK, the National Non-Food Crops Center found that any UK bioSNG plant built by 2020 would be highly likely to use ‘clean woody feedstocks’ and that there are several regions of this source.

In the UK, using anaerobic digestion is growing as a means of producing renewable biogas, with nearly 50 sites built across the country. Ecotricity has announced plans to supply green gas to UK consumers via the national grid. Centrica has also announced that it will soon begin gas, manufactured from sewage, into the gas grid. In Canada, FortisBC, a gas provider in British Columbia, has recently begun gas supply.

Sustainable SNG is produced by high temperature oxygen blown slagging co-gasification at 70 to 75 bar of liquid and solid contaminated wood, biomass, negative cost and non-hazardous wastes, coal and natural gas. This uses coal to SNG technology developed on the market of SVZ Schwarze Pumpe. The same technology can be used to fertilize industry, where it is currently being developed in China, to the renewable energy industry. SNG can be compared with biogas, with fewer supply chain limitations. A range of fuels with an overall biogenic carbon content of 50 to 55% is technically and financially viable. Hydrogen is added to the fuel mix during the gasification process, and carbon dioxide is removed by the gas purge ‘slip stream’ syngas clean-up and catalytic methanation stages. Large Scale Sustainable SNG will enable the UK to be substantially more carbon-intensive, while maintaining the existing operational and economic relationship between the gas and electricity grids. Carbon capture and sequestration can be added to this additional cost, thus making progressively bettering the bottom line of carbonization of the existing gas and electricity grids at low cost and operational risk. Cost benefit studies indicate that large scale 50% biogenic carbon content sustainable SNG can be injected into the high pressure gas transmission grid at a cost of around 65p / therm. At this cost, it is possible to re-process fossil natural gas, used as an energy input into the gasification process, into 5 to 10 times greater quantity of sustainable SNG. Large scale sustainable SNG, combined with continuing natural gas production from UK continental shelf and unconventional gas, will potentially enable the cost of UK to be de-coupled from international oil denominated ‘take or pay’ gas supply contracts. applications: gas supply contracts. applications: gas supply contracts. applications:

Incomplete to be renewable, biogas creates similar environmental pollutants as ordinary natural gas fuel, such as carbon monoxide, sulfur dioxide, nitrogen oxide, hydrogen sulfide and particulates. Any unburned gas that escapes contains methane, a long lived greenhouse gas. The key difference is that it is carbon neutral, the carbon dioxide is in the biomass is naturally renewed in each generation of plants, rather than being released from fossil stores and increasing atmospheric carbon dioxide.