Carbon capture has failed. So what should we do instead?

Drax and Eggborough power stations in England. Image: Pete Richman/creative commons.

For years, optimists have talked up carbon capture and storage (CCS) as an essential part of taking emissions out of electricity generation. Yes, build wind and solar farms, they have said, but they can’t be relied on to produce enough power all the time. So we’ll still need our fleet of fossil-fuel-burning power stations; we just need to stop them pumping carbon dioxide (CO₂) into the atmosphere.

Most of their emphasis has been on post-combustion capture. This involves removing CO₂ from power station flue gases by absorbing them into an aqueous solution containing chemicals known as amines.

You then extract the CO₂, compress it into a liquid and pump it into a storage facility – the vision in the UK being to use depleted offshore oil and gas fields. One of the big attractions with such a system is it could be retrofitted to existing power stations.

The big let-down

But ten years after the UK government first announced a £1bn competition to design CCS, we’re not much further forward. The reason is summed up by the geologist Lord Oxburgh in his contribution to the government-commissioned report on CCS published last year:

There is no serious commercial incentive and it will stay that way unless the state demonstrates there is a business there.

The problem is that the process is costly and energy intensive. For a gas-fired power station, you typically have to burn 16 per cent more gas to provide the capture power. Not only this, you end up with a 16 per cent increase in emissions of other serious air pollutants like sulphur dioxide, nitrogen oxides and particulate matter. Concerns have also been expressed about the potential health effects of the amine solvent used in the carbon capture.

You then have to contend with the extra emissions from processing and transporting 16 per cent more gas. And all this before you factor in the pipeline costs of the CO₂ storage and the uncertainties around whether it might escape once you’ve got it in the ground. Around the world, the only places CCS looks viable are where there are heavy state subsidies or substantial additional revenue streams, such as from enhanced oil recovery from oilfields where the CO₂ is being pumped in.

Well, say the carbon capture advocates, maybe another technology is the answer. They point to oxy-combustion, a system which is close to reaching fruition at a plant in Texas.

First proposed many years ago by British engineer Rodney Allam, this involves separating oxygen from air, burning the oxygen with the fossil fuel, and using the combustion products – water and CO₂ – to drive a high-pressure turbine and produce electricity. The hot CO₂ is pressurised and recycled back into the burners, which improves thermal efficiency. It has the additional advantage that CO₂ is also available at pressures suitable for pipeline transportation.

It is, according to some enthusiasts, the “holy grail” of CCS. Admittedly it looks promising, but I wouldn’t go that far. It’s not suitable for retrofitting existing power stations. With many existing stations viable for several decades, this will do little for immediate emissions. And you are still obtaining and moving fossil fuels in large quantities, with the resultant emissions along the way. Finally, my experience would indicate that there is always very significant cost growth with new technology scaled up to industry.

Number crunching

One UK post-combustion CCS project that was cancelled earlier this year was the joint-venture between SSE and Shell at the Peterhead gas-fired ation in northeast Scotland. It aimed to capture 10m tonnes of CO₂ over a 10-year period and store it 2km under the North Sea.

Let’s put this saving into context. The diagram below summarises the amount of power produced and used in the UK. It shows that the country uses 108 terawatt hours (TWhrs) of domestic electricity per annum.

 

UK electricity generation/consumption. All numbers are in terawatt hours (TWhrs). Image: DECC.

Of this domestic usage, 16 per cent goes to cooking. Boiling kettles makes up 34 per cent – that’s 5.9TWhrs per annum, the equivalent of a 670MW power station. Domestic kettle use is particularly inefficient as we regularly overfill our kettles. We could save at least half the energy if we boiled only what we need to make tea and coffee.

That would negate the need for 335MW of power. Now compare that to what CCS would have saved from Peterhead – 85 per cent of a 400MW gas turbine, or 340MW. Simply by not overfilling our kettles, we could remove about the same amount of CO₂. Unlike CCS, let alone oxy-combustion, we could do this immediately, for free, and cut our electricity bills and remove various air pollutants at the same time.

Of course, being kettle smart will only deliver a fraction of the UK’s required carbon reduction goals. It’s only about 3TWhrs out of the approximately 170TWhrs produced by gas-fired power in the UK each year. But it hopefully illustrates why energy efficiency is a much smarter way of reducing carbon and other harmful air emissions than CCS.


If we took the same approach to lighting, computer monitors, TVs on stand-by, running water and everything else, it becomes a very different proposition. If we could achieve the aim of a carbon-neutral house, we could shut down half the UK’s existing gas-fired power stations. And if industry and other non-domestic consumers made energy savings of the order of 20 per cent, that would bring down the gas-fired power requirement by a corresponding percentage.

Is 20 per cent realistic? As a chemical engineer with a 40-year industrial career, I am confident it is. Key areas to be considered would be pump and compressor efficiency, energy use in separation processes, combined heat and power, furnace fuel management, green concrete and energy integration.

Together with the government giving greater priority to renewable energy like offshore wind and solar, you have a viable plan for delivering the UK’s carbon goals. CCS may still have its place, but as a means of removing carbon emissions from burning things like wood and rubbish as opposed to fossil fuels. Suffice to say it looks more promising on that front.

The ConversationBut in short, it is time for governments to stop wasting time and money on technologies like CCS that aren’t working. They need to finally get serious about leading a major drive for energy efficiency instead.

Tom Baxter is senior lecturer in chemical engineering at the University of Aberdeen.

This article was originally published on The Conversation. Read the original article.

 
 
 
 

Covid-19 is highlighting cities' unequal access to green space

In the UK, Londoners are most likely to rely on their local park for green space, and have the best access to parks. (Leon Neal/Getty Images)

As coronavirus lockdowns ease, people are flooding back to parks – but not everyone has easy access to green space in their city.

Statistics from Google show that park attendance in countries across the globe has shot up as people have been allowed to move around their cities again.

This is especially true in urban areas, where densely populated neighbourhoods limit the size of private green space – meaning residents have to go to the park to get in touch with nature. Readers from England can use our interactive tool below to find out how much green space people have access to in their area, and how it compares to the rest of the country.

 

Prime Minister Boris Johnson’s announcement Monday that people are allowed to mingle in parks and gardens with groups of up to six people was partially following what people were doing already.

Data from mobile phones show people have been returning to parks across the UK, and also across Europe, as weather improves and lockdown eases.

People have been returning to parks across the world

Stay-at-home requirements were eased in Italy on 4 May, which led to a flood of people returning to parks.

France eased restrictions on 1 May, and the UK eased up slightly on 13 May, allowing people to sit down in public places so long as they remain socially distanced.

Other countries have seen park attendance rise without major easing of lockdown – including Canada, Spain, and the US (although states there have individual rules and some have eased restrictions).

In some countries, people never really stopped going to parks.

Authorities in the Netherlands and Germany were not as strict as other countries about their citizens visiting local parks during lockdown, while Sweden has famously been avoiding placing many restrictions on people’s daily lives.


There is a growing body of evidence to suggest that access to green space has major benefits for public health.

A recent study by researchers at the University of Exeter found that spending time in the garden is linked to similar benefits for health and wellbeing as living in wealthy areas.

People with access to a private garden also had higher psychological wellbeing, and those with an outdoor space such as a yard were more likely to meet physical activity guidelines than those without access to outdoor space. 

Separate UK research has found that living with a regular view of a green space provides health benefits worth £300 per person per year.

Access is not shared equally, however, which has important implications for equality under lockdown, and the spread of disease.

Statistics from the UK show that one in eight households has no garden, making access to parks more important.

There is a geographic inequality here. Londoners, who have the least access to private gardens, are most likely to rely on their local park for green space, and have the best access to parks. 

However the high population in the capital means that on the whole, green space per person is lower – an issue for people living in densely populated cities everywhere.

There is also an occupational inequality.

Those on low pay – including in what are statistically classed as “semi-skilled” and “unskilled” manual occupations, casual workers and those who are unemployed – are almost three times as likely as those in managerial, administrative, professional occupations to be without a garden, meaning they rely more heavily on their local park.

Britain’s parks and fields are also at significant risk of development, according to new research by the Fields in Trust charity, which shows the number of people living further than a 10-minute walk from a public park rising by 5% over the next five years. That loss of green spaces is likely to impact disadvantaged communities the most, the researchers say.

This is borne out by looking at the parts of the country that have private gardens.

The least deprived areas have the largest gardens

Though the relationship is not crystal clear, it shows at the top end: Those living in the least deprived areas have the largest private green space.

Although the risk of catching coronavirus is lower outdoors, spending time in parks among other people is undoubtedly more risky when it comes to transmitting or catching the virus than spending time in your own outdoor space. 

Access to green space is therefore another example – along with the ability to work from home and death rates – of how the burden of the pandemic has not been equally shouldered by all.

Michael Goodier is a data reporter at New Statesman Media Group, and Josh Rayman is a graphics and data visualisation developer at New Statesman Media Group.