Article - Issue 46, March 2011

Cutting carbon in the 2020s

Professor Roger Kemp FREng

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Professor Roger Kemp FREng

Professor Roger Kemp FREng

Cutting Carbon in the 2020s

The Fourth Carbon Budget - Reducing emissions through the 2020s was published by the Climate Change Committee in December 2010. The 200 page report sets out the Committee’s advice for the period 2023-27; the UK government will propose draft legislation for the fourth budget in spring 2011. Academy Fellow Professor Roger Kemp assesses the report, its targets and the actions needed to make the recommendations a reality.

It was good to see the confidence shown in the engineering profession by the recent report issued by the Climate Change Committee (CCC). However, technology cannot, by itself, solve the problem of CO2 emissions.

When first published, the previous government’s Climate Change Bill set a target of a 60% cut in CO2 emissions by 2050, excluding international aviation and shipping. The target was based on the recommendation of the Royal Commission on Environmental Pollution in its June 2000 report Energy – The Changing Environment.

Late in the legislative process, in October 2008, the government moved the 2050 goalposts from a 60% cut to an 80% cut in emissions. In the weeks following the Climate Change Act, The Royal Academy of Engineering realised that this commitment would be hugely challenging and set up a study on how the UK could meet its obligations. The outcome was the report Generating the Future, released in March 2010, which showed that, under any realistic scenarios, continuing to heat houses by gas boilers and to power road transport by petrol and diesel is incompatible with the 2050 commitment.

The least complicated route to reducing the dependence on petrol and diesel is the widespread adoption of electric vehicles and plug-in hybrids. In July 2009, the Academy launched a study that resulted in the publication, in May 2010, of Electric Vehicles – charged with potential. The report was timely as the CCC now proposes that 60% of new cars should be powered by electricity by 2030 – a higher figure than the industry has assumed to date and one that will require large investment in recharging infrastructure.

However, electric vehicles are only as ‘green’ as the electricity that charges their batteries. Merely swapping petrol or diesel cars for electric vehicles will not solve our carbon emissions problem on its own. As the CCC has recognised, while most electricity in the UK is still generated by burning gas and coal, the difference between an electric car and a small, low-emission petrol or diesel car can be negligible.

The contribution of renewable and low-carbon generation to the UK’s energy supply is one of the lowest in Europe. The report Generating the future identified the massive change programme and robust government leadership that will be required to meet the 2050 target. There is no single solution: we will need a range of new low-carbon energy sources, including nuclear power stations, wind farms and tidal barrages.

The CCC report proposes a target for the almost complete decarbonisation of electricity supply by 2030. On 7 December 2010, the day the report was released, there was a peak electricity demand of 60 GW in the UK, of which renewable energy provided less than 1GW and nuclear power 8GW. These figures indicate the scale of the challenge.

The challenge is made even more difficult by plans for domestic and commercial heating. The CCC is proposing that, by 2030, heat pumps fed from renewable energy should provide a quarter of domestic heating. There are 25 million households in Britain; converting a quarter of these will require six million heat pumps. Back-of-the-envelope calculations (replacing six million boilers, each 20 kW with a heat pump having a coefficient of performance of three) suggest that this could increase the peak electrical demand by more than 30 GW – a 50% increase in the load seen by the grid.

It should be borne in mind that all but one of Britain’s nuclear stations are due to be de-commissioned by 2025 and most existing wind turbines will be coming up for renewal before then. The CCC plans represent the construction of a new nuclear power station or a fossil-fuel powered one fitted with carbon capture and storage every year for the next 20 years, plus tens of thousands of wind turbines and other renewable schemes. In terms of engineering feasibility, this is possible: whether it is economically and politically achievable is another matter.

Renewable and nuclear energy have high capital costs but low running costs. Investment in renewables is thus only attractive if there is a steady market for the electricity. The opposite side of this coin is that building low-carbon generating stations to cope with occasional cold spells in winter, such as those in December 2010, is highly unattractive. It is not obvious that the CCC’s proposals for both a decarbonised electricity system and a transfer of domestic heating to heat pumps fed from renewable electricity is possible without large subsidies, either directly from the Treasury or indirectly via greatly increased electricity prices.

It seems that heat is the Cinderella of energy policy: millions of words have been written about nuclear power, renewables and electric vehicles, but few people have analysed the demand for low-grade heat for homes and how we could meet it without high CO2 emissions. The Academy has started a study in this area to tackle the question of whether decarbonisation of heat is ‘do-able’ at a price the country is prepared to pay.

The UK’s representatives went into the Copenhagen talks with a strong political and moral commitment to decarbonise our energy use but little idea of how the objective might be achieved at an affordable price. The CCC’s report is an excellent response to the question: how could the objectives of the Climate Change Act 2008 be met? Whether it represents the best compromise between practicality, affordability, security of energy supply and carbon emissions is a question that the engineering community urgently needs to address.


Professor Roger Kemp FREng, a Professorial Fellow at Lancaster University, spent most of his career in the rail industry where, until 2004, he was UK Technical & Safety Director of Alstom Transport. In the early 1980s, he was Engineering Manager of Lucas Electric Vehicle project and, in the early 1990s, was Project Director of the group that built the Eurostar trains.

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