Comparative study of the conversion, transport and storage technologies relevant to CO2 value chains

MEng in Chemical Engineering project; Mr. Sean Jarvis (student)

A key technology in meeting emissions target is carbon capture and storage. As CCS technologies start to be adopted by energy producers and become more widespread, a large quantity of CO2 will be captured and stored underground. Instead of treating this CO2 as a waste gas and expending energy for its transport and storage, some of it can be used as a raw material to produce alternative fuels and valuable chemicals using excess renewable energy generated when the demands for energy are low. There are vast sources of renewable energy in the UK but only a small fraction is being used because of the inability of the existing energy infrastructure to deal with the intermittency of supply.

For example, syngas and short chain olefins (C2-C3), which can be produced from CO2 reactions, along with aromatics, are the most important base materials for the petrochemical industry and thus form the base of the entire value chain of that industry. There are different ways to obtain syngas from CO2: via reverse water gas shift using renewable H2, dry reforming of methane (which can also be obtained from CO2 through the Sabatier reaction), electrochemical reduction and solar thermo-chemical splitting. There are also many biomass-to-syngas routes. Syngas can be converted to alternative transport fuels in the form of higher hydrocarbons and alcohols, to C2-C3 olefins and to methanol. Methanol can also be produced from the same reactants that produce syngas, using different catalysts. Methanol is an important energy vector, so much so that many researchers refer to a “methanol economy” comparable to the “hydrogen economy”. In addition to being used directly as a transport fuel, it can be converted to dimethyl ether, which is an alternative to diesel, and can also be converted to C2-C3 olefins. Furthermore, the hydrogenation of CO2 results in formic acid, which is an alternative method for storing H2 because of its favourable volumetric density thus allowing for easy transport and storage.

This project will identify and map out all of the possible pathways and technologies for CO2 utilisation (n.b there may be more than one technology for each pathway). We will research each technology and explain the working principle, classifying them according their TRLs (Technology Readiness Level), and compare them based on their technical and economic characteristics, e.g. efficiency, capital and O&M costs, typical lifetime, environmental impacts (e.g. GHG emissions), advantages and limitations. In addition to conversion technologies, this will include technologies for storage of resources and transport infrastructures. Note that resources include all of the materials and energy streams considered in the value chain, not just the raw materials/primary energy resources and final products but also any intermediates, by-products and wastes.