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.

 
 
 
 

Everything you ever wanted to know about the Seoul Metro System but were too afraid to ask

Gwanghwamoon subway station on line 5 in Seoul, 2010. Image: Getty.

Seoul’s metro system carries 7m passengers a day across 1,000 miles of track. The system is as much a regional commuter railway as an urban subway system. Without technically leaving the network, one can travel from Asan over 50 miles to the south of central Seoul, all the way up to the North Korean border 20 miles north of the city.

Fares are incredibly low for a developed country. A basic fare of 1,250 won (about £1) will allow you to travel 10km; it’s only an extra 100 won (about 7p) to travel every additional 5km on most lines.

The trains are reasonably quick: maximum speeds of 62mph and average operating speeds of around 20mph make them comparable to London Underground. But the trains are much more spacious, air conditioned and have wi-fi access. Every station also has protective fences, between platform and track, to prevent suicides and accidents.

The network

The  service has a complex system of ownership and operation. The Seoul Metro Company (owned by Seoul City council) operates lines 5-8 on its own, but lines 1-4 are operated jointly with Korail, the state-owned national rail company. Meanwhile, Line 9 is operated jointly between Trans-Dev (a French company which operates many buses in northern England) and RATP (The Parisian version of TfL).

Then there’s Neotrans, owned by the Korean conglomerate Doosan, which owns and operates the driverless Sinbundang line. The Incheon city government, which borders Seoul to the west, owns and operates Incheon Line 1 and Line 2.

The Airport Express was originally built and owned by a corporation jointly owned by 11 large Korean firms, but is now mostly owned by Korail. The Uijeongbu light railway is currently being taken over by the Uijeongbu city council (that one’s north of Seoul) after the operating company went bankrupt. And the Everline people mover is operated by a joint venture owned by Bombardier and a variety of Korean companies.

Seoul’s subway map. Click to expand. Image: Wikimedia Commons.

The rest of the lines are operated by the national rail operator Korail. The fare structure is either identical or very similar for all of these lines. All buses and trains in the region are accessible with a T-money card, similar to London’s Oyster card. Fares are collected centrally and then distributed back to operators based on levels of usage.

Funding

The Korean government spends around £27bn on transport every year: that works out at 10 per cent more per person than the British government spends.  The Seoul subway’s annual loss of around £200m is covered by this budget.

The main reason the loss is much lower than TfL’s £458m is that, despite Seoul’s lower fares, it also has much lower maintenance costs. The oldest line, Line 1 is only 44 years old.


Higher levels of automation and lower crime rates also mean there are fewer staff. Workers pay is also lower: a newly qualified driver will be paid around £27,000 a year compared to £49,000 in London.

New infrastructure is paid for by central government. However, investment in the capital does not cause the same regional rivalries as it does in the UK for a variety of reasons. Firstly, investment is not so heavily concentrated in the capital. Five other cities have subways; the second city of Busan has an extensive five-line network.

What’s more, while investment is still skewed towards Seoul, it’s a much bigger city than London, and South Korea is physically a much smaller country than the UK (about the size of Scotland and Wales combined). Some 40 per cent of the national population lives on the Seoul network – and everyone else who lives on the mainland can be in Seoul within 3 hours.

Finally, politically the biggest divide in South Korea is between the south-west and the south-east (the recently ousted President Park Geun-Hye won just 11 per cent of the vote in the south west, while winning 69 per cent in the south-east). Seoul is seen as neutral territory.  

Problems

A driverless train on the Shinbundang Line. Image: Wikicommons.

The system is far from perfect. Seoul’s network is highly radial. It’s incredibly cheap and easy to travel from outer lying areas to the centre, and around the centre itself. But travelling from one of Seoul’s satellite cities to another by public transport is often difficult. A journey from central Goyang (population: 1m) to central Incheon (population: 3m) is around 30 minutes by car. By public transport, it takes around 2 hours. There is no real equivalent of the London Overground.

There is also a lack of fast commuter services. The four-track Seoul Line 1 offers express services to Incheon and Cheonan, and some commuter towns south of the city are covered by intercity services. But most large cities of hundreds of thousands of people within commuting distance (places comparable to Reading or Milton Keynes) are reliant on the subway network, and do not have a fast rail link that takes commuters directly to the city centre.

This is changing however with the construction of a system modelled on the Paris RER and London’s Crossrail. The GTX will operate at maximum speed of 110Mph. The first line (of three planned) is scheduled to open in 2023, and will extend from the new town of Ilsan on the North Korean border to the new town of Dongtan about 25km south of the city centre.

The system will stop much less regularly than Crossrail or the RER resulting in drastic cuts in journey times. For example, the time from llsan to Gangnam (of Gangnam Style fame) will be cut from around 1hr30 to just 17 minutes. When the three-line network is complete most of the major cities in the region will have a direct fast link to Seoul Station, the focal point of the GTX as well as the national rail network. A very good public transport network is going to get even better.