Decarbonisation Technology - February 2022 Issue

range of refrigeration and cooling across industrial applications and food production.

Fuel switching and intensifying processes When devising a decarbonisation strategy, it makes sense to do the easier things first. Being more efficient with the use of any fuel falls into that category; using less fuel emits less carbon. Process intensification is the key to doing more with less. One approach is to burn a fuel using pure oxygen, or a mixture of oxygen and recirculated flue gas, instead of air. This approach intensifies the combustion process, which reduces fuel consumption and can deliver better temperature uniformity. Depending on the nature of the process, it is possible to reduce fuel consumption by between 10 and 50%, with a consequent reduction in carbon. In terms of fuel savings, the economic benefits of process intensification vary from case to case. A reduction in natural gas costs can be offset by the additional cost of using oxygen in the combustion process. However, adding carbon tax savings into the economic model makes the business case compelling for process intensification. Industries that can benefit from intensification include those dependent on high-temperature furnaces where there is a high proportion of natural gas combustion in their processes. These include industries such as glassmaking, steel, and the minerals sector, including cement production. Other applications that burn natural gas may be candidates for a ‘blending’ approach to fuel switching where hydrogen is mixed with the natural gas before combustion. Trials in the UK are under way to demonstrate that blending up to 20% volume of hydrogen with natural gas is a safe and lower carbon alternative for home cooking and heating appliances. Alternative refrigeration It is not only high temperature processes that can benefit from the use of alternative gases to help decarbonise; refrigeration and cooling can benefit too. While freezer units are typically powered using electricity, it is also possible to use liquid nitrogen to facilitate cooling. By enabling fuel flexibility, businesses have a mechanism to avoid volatile electricity prices. A stored tank of nitrogen, which has been produced using green electricity at a known cost, offers a means of fuel switching from the grid supply at times when the cost of wholesale electricity is high. The nitrogen gas effectively acts as an energy store for a wide

Carbon capture As well as being integral to the process of

producing blue hydrogen, there are other industrial processes where carbon capture, utilisation and storage (CCUS) is currently the only option available for decarbonisation. CCUS involves the capture of CO 2 from the industrial process, its transport, and subsequent use or sequestration. While the oil majors were early adopters of the technology, CCUS is gaining more traction as a decarbonisation technology for industry and power generation. For large volumes, the CO 2 will need to be sequestered, but there is also the potential to store carbon in, for example, aggregates. This approach offers the potential for additional revenue streams and reduced exposure to future carbon prices. There are several technology choices available for carbon capture, broadly categorised as pre-combustion, oxy-fuel, and post-combustion. BOC has experience of all three approaches and can best assess and determine the most cost-effective approach for a particular carbon emitting process. Mobility Transport accounts for over a quarter of the UK’s emissions, so it remains a prime target for urgent decarbonisation. The automotive industry is building momentum around delivery of a growing range of battery electric vehicles (BEV), primarily targeting private motorists. The key driver for the growth of BEVs is the UK’s 2030 ban on the sale of new petrol and diesel cars. However, there is a much less clear case for the use of battery electric powertrains with large and heavy vehicles such as buses, HGVs, and trains; heavier vehicles require large-capacity, heavy batteries, which penalise range. By contrast, hydrogen is proven as a fuel for buses, trains, and trucks without incurring a weight penalty. It has a high energy density and refuelling can be carried out from a dispensing pump in minutes to provide a range of hundreds of miles. Many UK councils and local authorities are planning to develop hydrogen refuelling stations (HRS) to provide back-to-base refuelling for bus fleets and maintenance vehicles, including gritter and refuse trucks. Extending hydrogen hub access to business fleets, such as delivery vehicles and taxis, as well