Stephen Tetlow MBE CEng FIMechE, Chief Executive of the Institution of Mechanical Engineers, discusses practical solutions to energy supply vulnerability.

UK demand for electricity is set to double by 2050. Over the same period, ambitious climate change targets need to be met. The questions is how the UK will be able to meet these conflicting demands in a way that is low carbon, secure and not prohibitively expensive for consumers - some of whom are already facing energy poverty.

Gas-fired power plants: the short-term solution?

In the short-term we are seeing closures of a number of ageing nuclear and coal-fired power stations. To plug the gap, utilities are turning to gas-fired power plants, which are relatively quick and cheap to build. Gas-fired power plants don't have the long lead times of nuclear plants. They are more efficient and far less polluting than their conventional coal-powered equivalents. Wholesale natural gas prices have fallen in recent years due to increasing levels of shale-gas exploration in the US which has created a glut in the international gas market. This all combines to make gas-fired power plants attractive investments for utilities wanting to produce cost-efficient electricity.

But in the longer-term, overreliance on gas-fired power plants will prove costly. The UK's oil and gas reserves are dwindling which means the country will need to meet 80% of its gas demand from imports by 2020. This will leave the UK excessively vulnerable to international competition for gas supplies. We will be at higher risk to politically-motivated gas supply disruptions, such as the blockade by Russia of its gas exports to Europe in January 2009.

Climate-change policy could also ramp-up costs of this form of generation. Gas power plants now have to be built "carbon-capture ready". This means ready to have Carbon Capture and Storage (CCS) technology retrofitted onto the plant to reduce emissions. At further cost, it is likely that older UK gas-fired power plants will all have to be fitted with CCS technology in order to meet climate-change obligations at some point in the future.

CCS works by capturing carbon dioxide (CO2) (a greenhouse gas causing climate change) which is emitted as a by-product of fossil-fuel power generation. The captured CO2 is transported, normally via pipeline, to be stored in suitable sites such as depleted oil and gas fields. The technology is still to be tested on a full-sized power plant. Currently the focus is on developing CCS on coal-fired power plants, but there are projects planned for developing gas-related options. The Intergovernmental Panel on Climate Change estimates that the installation of CCS technology will increase the cost of generating electricity at a power plant by between 21% - 91%. Somehow, we will all have to face up to these costs.

Can nuclear plug the gap?

After years of political wrangling and public debate, nuclear power building looks set to become a reality again for the UK. EDF is set to build the first nuclear power plant in the country for over 20 years at Hinkley Point C in West Somerset. Nuclear power production is low-carbon and uranium supplies are sourced from relatively stable and dependable countries like Canada and Australia. According to the World Nuclear Association, at current usage levels the world has between 70-80 years worth of supplies left - although there is expectation that the re-use of spent fuel and the development of more efficient reactors may prolong the use of this technology. Nuclear power is ideally suited to provide baseload electricity generation for continuous electricity demand. But it is difficult to use to meet short-term peaks in electricity demand. While it is likely that some UK nuclear power plants will be built - questions remain as to exactly how many. Whether in a bout of politically-motivated NIMYBYism or genuine environmental concern, the Scottish Government has vowed not to host any nuclear plants in Scotland and the Welsh Assembly remains opposed to new nuclear plants in Wales. Last year, Scottish and Southern Energy (SSE) decided to pull out of plans to build a new nuclear power plant in Cumbria, while EDF was forced to delay its plans to start construction of Hinkley Point C following events at the Fukushima Daiichi plant in Japan. It now seems unlikely that any new nuclear plant will be operational in the UK before 2020, years behind timelines set out by Government in 2008.

Looking at UK renewables

Renewable technologies like wind, wave, tidal turbines and solar arrays, are not only low carbon, they also have the potential to reduce the country's dependency on imported primary fuels. Most of the focus in recent years in the UK has been on the deployment of wind farms. They bring the political advantage, if constructed off-shore, of avoiding the substantial public opposition and planning issues associated with placing the turbines in a country with one of the highest population densities in Europe.

However the challenge with wind turbines, as with wave and solar devices, is that the supply of energy is intermittent. This means in the absence of storage technology or smart grid systems - both of which are in infancy stages of development - significant 'on-demand' back-up generating capacity is required. These back-up plants have to be maintained on standby in readiness for occasions when peak demand coincides with low availability of wind power. The provision of this back-up adds indirect costs to renewable energy.

The way forward

What is clear, and has been acknowledged by Government, is that there is no silver-bullet to meet the projected growth in UK electricity demand. We need a balanced energy mix, with nuclear, gas, CCS power plants and renewables all playing a role in supplying reliable and low carbon electricity.

To achieve this, the Institution of Mechanical Engineers has been advocating an energy hierarchy.

Priority one is energy conservation. This is best achieved through behavioural change, such as switching appliances off when they are not being used. Engineering solutions will also contribute, for example through the provision of smart technologies to provide better information to help consumers make conservation choices.

Priority two is energy efficiency. This focuses on engineering improvements to increase the amount of useful output obtained from all available energy sources.

The next priorities are to bring forward the following schemes:

• UK Government needs to ensure there are better links to the European electricity network, and enable a massive upgrade of the National Grid. A European Super Grid would enhance security of supply, and allow the country to benefit from the peaks and troughs in electricity prices elsewhere in Europe. There is an urgent need to bring forward a £19 billion investment in the UK grid to accommodate new generating capacity such as new nuclear plants and renewables.
• Urgent investment is also needed into Research Development and Deployment (RD&D) of electricity storage. The ability to store electricity will reduce the need for expensive back-up capacity for intermittent renewable technologies. The Government must also step-up its support for renewable technologies, such as tidal power, which are more predictable than wind power.
• The nascent CCS industry is in the early stages of development and needs much stronger Government support. We must step-up our efforts to support new projects, particularly in view of the UK's flagship CCS project at Longannet in Scotland being scrapped in October 2011. The opportunity to lead the world in developing and exporting this technology is ebbing away.

But perhaps the most important issue facing us is clarity of purpose and a vision to secure our energy needs and to protect our future generations from the perils of climate change. As a country, for too long we have been tinkering at the edges, dithering in indecision and lacking in the long-term vision of some of our neighbours. Tactics such as the Government's Electricity Market Reforms all help, but tactics without a strategy are like torches without batteries. Engineers can deliver the technology, but only Government can supply the leadership. There needs to be cross-party dedication to this vision, otherwise there is the real prospect of the lights going out in 2020.