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Last summer, the UK became the first G7 country to legislate for net zero carbon 鈥� the state of overall balance between carbon dioxide (CO2) emissions produced and emissions taken out of the atmosphere. An amendment to the Climate Change Act increased the target to reduce greenhouse gas emissions from 80 per cent to 100 per cent by 2050. It is an ambitious objective, and not one that can be reached by reducing emissions alone.

鈥淩educing emissions becomes harder and harder to do once we reach a certain level: in the UK (where total emissions were around 364 million tonnes in 2018), we might get to a low emissions economy with between 80 to 150 million tons of carbon dioxide equivalent still being released to the atmosphere,鈥� says Professor Nilay Shah (MEng Chemical Engineering 1988, PhD 1991), Head of the Department of Chemical Engineering. 鈥淭o go from there to net zero means having technologies that will take in air and scrub out the greenhouse gases.鈥�

Carbon capture essentially means trapping carbon dioxide at its emission source, transporting it to a storage location 鈥� usually deep underground 鈥� and isolating it. But achieving net zero is a huge task. From the fine details of tree-planting to technical breakthroughs in underground storage, and from global financial implications to the details of translation, there are any number of problems, processes and pathways.

In short, it鈥檚 just the kind of challenge that 51吃瓜网鈥檚 experts relish. However, according to Professor Shah, the simplest solutions to carbon capture are right here now, all around us.

鈥淚t doesn鈥檛 require us to invent anything exotic. It鈥檚 more a question of practical landscape management.鈥� Take trees, for example: along with getting rid of carbon dioxide, they also provide a multitude of other benefits, including improving the climate and biodiversity of an area.

"A well-managed forest with trees grown in rotation will produce wood that can be used in construction, and that鈥檚 yet another way of capturing carbon. The carbon that was in the atmosphere goes into the wood. Then the wood goes into a building, and that carbon is locked away for a long time,鈥� says Professor Shah. 鈥淭he only downside is that trees aren鈥檛 going to be enough on their own. We鈥檇 need an awful lot of trees!鈥�

Then there鈥檚 biochar, a charcoal-like material produced when agricultural materials are partially combusted. It鈥檚 carbon-negative: when biochar is used in soil, it traps carbon there while also improving the soil鈥檚 quality. Restoring coastal wetlands and peatlands will also improve the landscape鈥檚 ability to take up carbon dioxide, as will reducing ploughing in order to disturb the soil less.

鈥淚n the last two years, I鈥檝e seen a big change in the attitude of large companies,鈥� says Professor Shah. He cites , a large biomass and coal-fired power station in North Yorkshire that aims to get to net zero in 2030 by burning wood pellets from sustainable forests and utilising carbon storage technology. 鈥淲e鈥檙e also working with a very big company I can鈥檛 name yet that has made a huge commitment in this area. For many aspects of science and technology, this will be a golden age. Carbon capture is a big and complex thing but it is also really exciting, enthusing and engaging.鈥�

Core carbon capture and storage technologies are nothing new, says Dr Niall Mac Dowell, Reader in Energy Systems. Most of them were first deployed between 1900 and 1930, and are used all over the world today. 鈥淏ut there鈥檚 more to this kind of system transformation than just engineering technology,鈥� Dr Mac Dowell points out.

鈥淣obody is doing this for charity. The service being provided will be for removing CO2 from the atmosphere. And to do that effectively, we need to develop the institutions and frameworks for the monetisation and commercialisation of these services, and for appropriately valuing them.鈥�

For example, a ton of carbon stored underground will eventually become rock. The risk associated with its removal is zero. Use trees to capture carbon, however, and the risk rises: trees can die from pests, disease or fire. 鈥淪o how do we design a level of risk to that stored carbon, and price it appropriately? How many trees do you have to plan for to remove a ton of CO2?鈥�

Last year, Dr Mac Dowell鈥檚 lab won a grant from the EU鈥檚 Horizon 2020 research and innovation programme to grapple with questions such as these, working out how this new system might be designed 鈥� and how to make it fair, equitable and, most importantly, practical. 鈥淲e鈥檒l be looking into how deploying negative emission technologies interacts with the rest of the energy system,鈥� he says. 鈥淎nd we鈥檒l also be studying how we can make this transition in a way that benefits our broader society.鈥�

The transition is often framed in terms of trade-offs, Dr Mac Dowell points out, but it doesn鈥檛 have to be that way. 鈥淚 would argue that it鈥檚 unlikely 鈥� even with the experience of the current crisis 鈥� to be broadly socially acceptable that we have to drastically and rapidly change our lifestyles. So, we need to design transitions that aim to maximise growth. 鈥淲e are creating new industries and economies that will result in the creation and preservation of jobs and communities across the world.鈥�

The energy transition cannot happen immediately, points out Geoff Maitland, Professor of Energy Engineering 鈥� even by 2050, at least 20 per cent of our energy sources globally, and maybe up to 50 per cent, will still be fossil fuels. So how do we decarbonise these fossil fuels? Ten years ago, Maitland founded the Qatar Carbonate and Carbon Storage Research Centre (QCCSRC), a collaboration between 51吃瓜网, Qatar Petroleum, Shell and the Qatar Science and Technology Park, part of Qatar Foundation. It aimed to deepen understanding of how carbon can be efficiently stored underground in depleted oil and gas reservoirs and water-permeable rock formations called deep saline aquifers.

鈥淭his programme focused on how we can ensure both depleted oil and gas reservoirs and deep saline aquifers have the capacity to safely store the ten gigatons of CO2 that we鈥檝e got to store by 2050,鈥� says Professor Maitland. 鈥淭he big concern with this method is that when you put the CO2 down there, it stays there.鈥�

They used x-ray imaging tomography at both the micropore scale and the larger core scale to examine the fluids inside rocks. 鈥淎nd we identified the trapping mechanisms in a way people hadn鈥檛 understood before,鈥� says Professor Maitland. 鈥淭he natural seals of low-permeability rocks have kept oil and gas in place for millions of years. The CO2 gets trapped by capillary forces in the same way that oil does; it鈥檚 trapped by surface tension. Injecting it requires high pressure, but not too much, otherwise you fracture the rock, and we did a lot of work identifying this window.鈥� Once injected, the CO2 gradually dissolves into the fluids in the rock, and eventually turns into carbonate minerals, trapping it permanently.

The project has already spawned numerous papers and take-ups in the field and paved the way for the large-scale adoption that will be needed by 2050. 鈥淲e have 20 to 25 large-scale projects worldwide now, and by 2050 we鈥檙e going to need about 5,000 or more,鈥� says Professor Maitland. 鈥淭hat鈥檚 a big jump 鈥� but the technology exists.鈥�

Having practical knowledge and solutions to reach net zero is one thing: getting them out there into the real world is quite another. That鈥檚 where the Grantham Institute for Climate Change and the Environment comes in.

鈥淲e are a bridge between the technical knowledge that we have at the university, the business and the policy community, and the general public,鈥� says Alyssa Gilbert, the Institute鈥檚 Director of Policy and Translation. 鈥淲e help them to make use of all that knowledge to make evidence-based decisions that can help deliver solutions today and in the future. We listen to those people so we can understand their queries and then we design information responses.鈥�

The recent Science in the City programme, for example, took 51吃瓜网鈥檚 experts into different City firms to talk about the technologies that will need to be implemented to deliver net zero emissions goals. 鈥淲e got some very good, insightful questions about the technology鈥檚 strengths and weaknesses,鈥� Gilbert says.

鈥淭hat informs a firm鈥檚 ability to make investments in those technologies. And that鈥檚 what we want to see 鈥� the shift of finance and investment from the things that damage our environment to the things that can solve our environmental challenges. It鈥檚 really exciting when we鈥檙e in the room with people who have access to funding decisions, asking us questions that we think can move the tide of money in the right direction.

51吃瓜网 is the magazine for the 51吃瓜网 community. It delivers expert comment, insight and context from 鈥� and on 鈥� the College鈥檚 engineers, mathematicians, scientists, medics, coders and leaders, as well as stories about student life and alumni experiences.

This story was published originally in 51吃瓜网 48/Summer 2020.