Decarbonisation Technology - November 2024 Issue

could fundamentally change the waste management system by decarbonising waste before it hits incineration and landfill. KEW’s advanced gasification technology The use of ACT operating at elevated pressure gasification (8 bar rather than atmospheric) allows the higher-efficiency conversion of carbon-rich feedstocks such as waste and non- recyclable materials and biomass into valuable products such as syngas (a mixture of hydrogen and carbon dioxide, CO₂). A feedstock can essentially be anything you put into the process, such as municipal solid waste (MSW) from households, commercial and industrial waste, medical waste, and biomass, including wood, crops, agricultural and forestry waste, and sewerage sludge. Unlike incineration, which burns waste materials in the presence of excess air to produce heat and ash, gasification uses limited oxygen to partially oxidise the feedstock (see Figure 3 ). This process generates syngas and reduces the volume of residual ash, offering a cleaner and more controlled approach to waste conversion. Being able to achieve a consistent hydrogen- rich, tar-free syngas composition regardless of the feedstock type and composition is a critical pathway to high-value energy molecules. Ideally co-located on waste disposal sites, it means any feedstock can be used to produce the same consistent compressed fuel (syngas), halving the energy needed to compress captured CO2 and drastically reducing costs and greenhouse gas emissions (see Figures 4 and 5 ). This could allow waste suppliers to convert their ‘dirtiest’ waste, which costs them (and

Combustion High presence of oxygen low heat

Gasication

Pyrolysis No oxygen high heat

Correct presence and balance of oxygen and high heat

Advanced Conversion Technology (ACT), such as advanced gasification, or Advanced Thermal Treatment (ATT), such as pyrolysis. Waste management in the UK currently relies heavily on incineration and combustion, both of which produce significant fossil CO2 emissions. However, by including innovative technologies that can transform waste into valuable resources while reducing carbon emissions, some emerging technologies will be severely disadvantaged. Given the lead times for changing waste management practices, many waste suppliers are looking for viable pathways to net-zero solutions and are currently trying to decarbonise via economically and technically challenging heat offtake or carbon capture, use and storage (CCUS). The expansion of the scheme while solutions are still needed puts it at risk of becoming counterproductive. Taxing waste-to-energy, such as waste-to-syngas and similar products, without a policy support scheme in place acknowledging their lower carbon nature could undermine their potential to reduce greenhouse gas emissions by placing too great an economic burden on their innovation. These technologies Figure 3 Combustion, gasification, and pyrolysis differ in their requirement for oxygen and heat

Non-recyclable waste from household, textiles and C&I and m unicipal s olid waste

Agricultural biomass, forestry residues, virgin or waste wood biomass

Sewage sludge, digestate Industrials’ byproduct waste e.g. pulp and paper clients, glass recycling clients

Figure 4 A variety of feedstocks can be used for gasification