Swindon is not the first place that springs to mind when it comes to revolutions; yet it was in the depths of north Wiltshire that a green gas revolution was unveiled at the end of last month, namely the launch of the world’s first commercially operating BioSNG (bio-substitute natural gas) plant that aims to make renewable gas from household waste, which will be injected into the gas grid.
In a partnership that includes National Grid Gas Distribution, advanced waste to energy and fuels company Advanced Plasma Power (APP), Wales & West Utilities and clean energy firm Progressive Energy, the concept – entitled, appropriately, GoGreenGas – is expected to have the capability to eventually produce affordable sustainable fuel for homes and trucks. Indeed, the project partners go so far as to claim the technology could provide fuel for all of Britain’s heavy goods vehicles or meet a third of domestic heating demand.
The significance of the venture was emphasised by Sir John Parker, chairman of APP’s advisory board, at the launch of the £25m commercial demonstration plant when he described it as being “at the very frontier of technology. This investment has been bold and involved significant risk-taking. Success here will create a new environmental fuel source that is of great importance and it should deliver something at the very frontier
of technology that will be a first in this country.”
The £25m demonstration plant is being funded by an £11m grant from the Department for Transport’s Advanced Biofuels Demonstration Competition, as well as Ofgem’s Network Innovation Competition and the project partners, along with an extra £6.3m from the National Grid announced at the launch. This is reported to complete the financing for the project and will enable construction of the commercial demonstration plant to begin at APP’s site in Swindon.
Once operational, the plant is expected to provide fuel for a fleet of 40 trucks belonging to Howard Tenens, a local logistics company, and will result in an 80% cut in greenhouse gas emissions for the vehicles. And as if this wasn’t enough, particularly in a sector where the construction of infrastructure has been known to take many years, the demonstration plant is expected to be able to supply gas to homes, businesses and community facilities by the first half of 2018 – in just over a year’s time.
The beauty of the technology behind the project is that no adaptations of domestic appliances are required to use BioSNG. This means no expensive new infrastructure, and no upheaval or inconvenience for future customers.
National Grid Gas Distribution chief executive Chris Train OBE says: “Developing green technologies such as BioSNG means our customers can keep on using our network and their existing household appliances such as boilers and cookers for affordable energy which will also be more sustainable and eco-friendly.”
European BioSNG facilities
According to Rolf Stein, CEO of APP, there are already a number of projects in Europe and the USA that produce BioSNG. “The 20MW GoBiGas facility in Sweden is producing renewable gas from wood residues. In France, Engie, the electric utility company, has committed substantial funds to a facility which is nearing completion of the construction phase, and a further plant is under development in Holland. Uniquely, our project is focused on the conversion of waste- derived biomass to BioSNG, as this represents the UK’s largest biomass resource,” explains Stein before adding: “The most difficult chasm of all is the challenge of commercialisation.”
Hence the significance of the launch of the commercial demonstration plant at APP’s site in Swindon. It is expected to take in 10,000 tonnes of waste from the local area and produce 22GWh of BioSNG – enough to heat 1,500 homes. It is also anticipated to reduce emissions of harmful greenhouse gases by 5,000 tonnes per annum.
Rob Wakely, deputy director of low carbon fuels at the Department for Transport, points out: We require an 80% reduction in greenhouse gas emissions, and low carbon liquid and gas fuels will be essential to meet targets. It is crucial for us to tackle the sectors beyond electrification, HGVs, shipping, etc, so advanced fuels are really important as they don’t impact on land use and food crops and will be compatible with existing infrastructure. They also offer strong economic benefits. We estimate the industry in advanced fuels could be worth £15bn.”
So confident is the consortium in the BioSNG project that it anticipates to see a fleet of full-scale green gas plants in operation by the next decade. The technology is also reported to have lower carbon costs than alternative approaches to decarbonising heat and transport. More green boxes to tick.
The process is carried out in several stages. Waste materials, including biomass, are supplied from the local Swindon Borough Council waste facility, and act as feedstock.
First, recyclable items are removed from the waste and the remaining materials are shredded and dried.
Next, the waste is gasified to convert it to syngas – a mixture of carbon monoxide, hydrogen and carbon dioxide – and exposed to a high temperature plasma arc to remove tars.
The tar-free syngas is then cooled and cleaned, and steam is introduced while the gas is passed over an iron catalyst ‘water gas shift reactor’, which reduces the carbon monoxide content and increases the hydrogen.
“Different feedstocks produce syngases with different CO:H2 ratios,” explains Chris Manson-Whitton, director at Progressive Energy. “The shift reaction can be ‘tuned’ to cater for different feedstocks.”
The gas then enters a succession of methanation reactors with nickel catalysts. “In these reactors, the quantity of catalyst and the gas flow rates are carefully selected to ensure a controlled reaction,” continues Manson-Whitton.
The gas exiting the reactors contains significant quantities of CO2 which are then removed using a chemical scrubbing system to produce a product with a high methane content.
Following the addition of an odorant, the product gas is then injected into Wales & West Utilities’ gas network, where it will be transported for use in homes or transport. Howard Tenens will take some of the gas from the network before compressing it to 300 bar at its nearby CNG filling station and using it to fuel HGVs.
“By operating over a significant period under true commercial conditions, the plant will help to remove the construction, operational and performance risks of the technology, giving confidence to potential developers and funders of even larger commercial-scale plants,” predicts Manson-Whitton. “We have a vision of city-based plants and the scale we are talking about will have the potential of generating 33% of the UK’s domestic heating.”
In brief: BioSNG production
Fuel preparation: waste or biomass feedstocks are shredded and dried and recyclates such as metals or dense plastics are removed.
Thermal conversion: The prepared feedstock is heated to convert it to a synthesis gas (syngas). The physical and chemical composition of waste and biomass feedstocks means that the syngas is contaminated by tars.
Tar treatment: Tars are converted to syngas using thermal, catalytic or plasma treatment or removed using water or oil- based scrubbing.
Gas cleaning and cooling: The gas is cooled. Ash and heavy metals are removed along with other contaminants such as acid or alkaline gases.
Compression: The syngas is compressed to simplify further processing.
Water gas shift: The syngas is reacted with steam over a catalyst bed to increase the ratio of hydrogen to carbon monoxide. Methanation: The syngas is passed over a catalyst bed to convert carbon monoxide and hydrogen to methane and water. Separation: Carbon dioxide is removed to produce methane-rich gas.
2010-2013: Feasibility study in process development
2014-2017: Design, build and test of pilot plant
2015-2018: Design, build and operate commercial demonstration plant
2018 onwards: Roll-out of plant delivery