Solving the UK’s coal conundrum1 December 2008
How to keep the lights on while maintaining the government’s commitment to reducing plant emissions.
The power cuts which hit the UK in late May, affecting over 500 000 people, were a clear warning that its ageing infrastructure is struggling. The head of one major utility, Dr Paul Golby of E.On UK, said the blackouts were a ‘small indication’ of what might occur if we do not start building new power stations.
Most industry insiders would agree with that assessment, and so does the government. Its latest modelling shows that the UK will need 20-25 GW of new power by 2020. However, the need for new plant which meets future demand and also lowers greenhouse gas and other harmful emissions is sending the estimates for new infrastructure spending into the stratosphere.
Consider the thorny issue of coal, which still accounts for the biggest share of the UK’s current electricity generation (37%, versus 36% for gas and 18% for nuclear). It is very hard to see how future demand can be met without coal continuing to play a significant rôle. But the costs of building ‘next generation’ coal plants are, without exaggeration, going to be gigantic.
As an example, let’s examine two ‘clean coal’ technologies, one now being deployed overseas, the other some distance in the future – integrated gasification combined cycle and carbon capture and storage.
IGCC offers some promise in lowered NOx and SOx emissions and the ability to produce hydrogen for use in, for example, fuel cells or engines that can provide power without producing CO2.
The problem with IGCC technology is that it is no more efficient than the current generation of supercritical power stations and considerably more expensive per installed MW, even without carbon capture. Its efficiency is possibly slightly higher than a comparable supercritical with carbon capture but there is a significant penalty in capital cost and (currently) in reliability. Current and medium term emissions legislation for NOx and SOx can be complied with more cost effectively than through gasification so the benefit of an IGCC plant rests primarily on its ability to produce hydrogen if a shift reactor is installed.
There are currently no IGCC plants in the UK and only a handful worldwide. Yet we have some indication of what the costs might be from proposed new plants in the USA. One of the largest US utilities, American Electric Power, has proposed building a 629 MW IGCC plant in Mason County, West Virginia at an estimated cost of over $1.5 billion. AEP has indicated that the plant will only be economically feasible if ‘costs can be recovered through the regulatory process’.
In seeking to promote CCS, the UK government decided to choose the ‘post combustion’ or ‘oxy-fuel’ model for its 2012 demonstration project. This can, in principle, be retrofitted to an existing coal-fired plant. But this does not make it any less expensive an enterprise. In fact, recent analysis from investment bank Climate Change Capital showed that the total costs of a demonstration post-combustion project in Europe would be over r1 bn, and not a commercially viable technology. It is unlikely to become so in liberalised markets until there is greater certainty in the price of carbon and/or further development.
The coal conundrum
So one of the biggest issues facing our utilities today is solving the coal conundrum: how can we continue to receive a significant proportion of our energy from coal when the existing infrastructure is ageing, and increasingly subject to failure, and when the costs of new plant which can take advantage of ‘cleaner’ coal are, quite simply, immense, (and more worryingly uncertain at least as far as the carbon capture costs and/or penalties are concerned). This is a more critical question still when the country loses 8.5 GW of coal-fired capacity by 2015, simply as a consequence of complying with the EU’s Large Combustion Plant Directive – which aims to reduce SOx and NOx emissions.
I would like to offer the following observations on the coal conundrum:
•Coal does have a major role to play in our future energy mix, even in a carbon constrained world. The economics and geo-politics of gas are changing so fast that it would be a mistake to assume that gas – with its lower capital costs and carbon footprint – can fill all the gaps in our existing coal capacity. The same goes for renewables and nuclear.
The government is right to talk about a balanced energy portfolio, and to set the framework for new nuclear build and change the planning laws to favour wind farms. But most experts agree that, given current technology, renewables cannot provide base load power for the UK. Even maintaining its existing nuclear capacity for the next twenty years will be a technical and economic challenge. Coal by contrast is plentiful, relatively inexpensive and available from politically stable areas of the world.
•There should be a stronger focus on maintaining and improving efficiency in existing coal capacity. Given that most existing coal plants were built in the late 1960s and early 1970s, with a design life of 25 to 30 years, it is tempting to believe that increasing problems at this stage are inevitable. But has enough resource been put into maintenance over the last 15 years or so? I would argue the answer to that question is no, and that it is one of the reasons why we are now seeing an increased level of failure. A combination of financial pressures in the years following privatisation and a fall in electricity price due to the ‘dash for gas’ did not provide the right drivers for investment in the plant. The evidence of the last few years is that operators have significantly increased maintenance expenditure, owing to an increase in market prices and the necessity to keep plant operational.
The good news is that advances in techniques are now putting much more science into the art of maintenance, allowing operators to assess the risks to plant much more accurately, and to make more cost-effective decisions, as for instance when a defect occurs in a high-temperature piece of plant, and there needs to be an assessment of whether it is safe to continue operating, or better to take the plant out of service. It is now possible to analyse and assess all of the relevant components in the plant in fine detail, then use sophisticated integrity management tools to predict how long the plant can continue running.
And modern risk assessment techniques can also help operators get a much more accurate macro picture of a power plant. Atkins has developed tools to analyse risks based on a systematic set of technical issues, such as plant availability, reliability, level of production, health and safety and environmental impact. This approach allows operators to have an overview of which systems might fail, and how, and what would be the consequences, allowing them to set budgeted priorities for plant maintenance. Key to success in this area is to get the contribution of the operators in this assessment.
This systematic risk management approach can also inform well focused plant refurbishment – identifying the critical components that will require replacing to meet or extend expected design life, and those for which the risk of continuing to operate is acceptable.
The power generation sector may be able to share methods with other capital intensive industries. For example, the energy Division within Atkins is exploring how its Fleet Management System, developed to provide clear visual and documentary asset information for oil and gas platforms, may be adapted for the power market.
•Ways to reduce emissions (including greenhouse gases) from coal fired stations should be investigated before billions are spent on CCS technologies. Carbon capture is the least developed of the gas emission controls. There are many competing or complementary techniques to take CO2 from flue gas but the market drivers for deployment are not yet strong or secure enough for widespread investment.
However, NOx and SOx emissions will be significantly reduced by 2015 when the Large Combustion Plant Directive is implemented – by a combination of plant closures and retrofit of technology such as SCR.
Using the kind of advanced maintenance techniques described above – improved analytical tools, better focused maintenance and refurbishment, and environmental retrofits – many of the existing coal-fire plants in the UK could have a much longer life-span than currently anticipated – with reduced pollution owing to the capture of NOx and SOx.
This will allow operators the necessary financial breathing space to consider how they are going to get new plant up and running, given all of the constraints discussed here. Hopefully it will also permit greater certainty to develop in the market for the price of carbon. Somewhat ironically, it would also make easier the planned expansion of the UK’s renewables portfolio – because maintaining existing coal plants would ease the strain on capacity and allow alternatives such as wind, marine and solar to develop without bearing the impossible burden of attempting to become the UK’s base load power source.
Donald McNicol is chief engineer-energy, at W S Atkins. He was a utility engineer for many years, and is now a consultant to some of the major companies in the field.