CHP: Dependable ... not Dispensable07/07/2017
In an article written for Construction & Civil Engineering Magazine, Chris Marsland, ENER-G's Head of Cogen Product and Technology, discusses how CHP is essential to the future energy mix.
I sometimes hear the flawed argument that with advancements in renewable energy, low carbon generating technologies such as combined heat and power (CHP) have had their day, and that modern power will be so cheap that it will reduce the need for energy efficiency.
In my opinion, CHP is the ultimate agile and flexible technology that has a useful contribution to make both during the transition years from fossil fuels to renewable energy and far beyond.
The contribution of CHP
Demand side response, climate change, greener buildings, the growth of district heating and smart grids, and the need to improve energy productivity, are all reasons why CHP will remain an important part of the UK's energy generation mix.
One of the weakest links in the current energy supply chain is wasted heat. Forty per cent of the UK’s energy is used to generate heat energy; and heat wasted from buildings accounts for half of our total energy emissions.
Research led by the Association for Decentralised Energy (ADE) has highlighted the problem of poor energy productivity, largely due to wasted heat. ADE estimates that 54% of energy used to produce electricity is being wasted via conventional power production, which relates to £9.5 billion per year.
CHP, or cogeneration, generates both heat energy and electricity from a single process, capturing and utilising waste heat to reach total efficiencies of around 90%. That's more than double the efficiency of conventional power production.
It consistently provides the most effective way of burning gas (including carbon-neutral fuels such as biogas), particularly for applications where there is a large heating or cooling demand over an extended period of time.
CHP's potential to achieve cost savings of up to 40% and reduce CO2 emissions by up to 30% add to its popularity. In addition, it scores in terms of versatility - since it is suitable for new and refurbished buildings, as a replacement for an ageing boiler plant, or in augmenting existing or new boilers.
In the current market of low wholesale gas prices and with UK tax-saving opportunities, such as exemption from the Climate Change Levy for small-scale installations, the financial returns of CHP can be highly attractive for the right sites. A return on investment of 3-5 years is typical for 'Good Quality' CHP.
Greener building strategy
CHP is making an important contribution towards the move to greener buildings. The government's construction strategy targets a 50% reduction in CO2 emissions from buildings by 2025. Most local authorities champion CHP as part of local planning and building regulation approvals, with assessments required to consider district heating networks and community heating schemes with CHP as a main energy source. The Government is also supporting the development of heat networks.
New buildings need to be greener, with designs that prove the development will be environmentally responsible and resource efficient throughout its lifetime. Local authorities insist on an energy strategy and/or sustainability policy statement, with planning applications showing how the design will reduce energy use via climate change resilience, resource efficiency and pollution reducing measures. In particular, BREEAM awards credits for the use of innovative, energy saving technology, such as CHP.
Securing and balancing power supply
CHP also plays a starring role in securing power supplies and underpinning the growth of intermittent renewable sources, such as wind and solar.
The technology is capable of offering grid support with minimal start up times, so not only does it serve as a transition technology towards a renewable future but it can also offer grid stability to prevent brown outs and black outs.
CHP systems have rotating momentum that provides system inertia – helping to stabilise the network and manage system stresses when there is wide fluctuation in power output, as is the case with wind and solar. As we move towards a future energy mix with a large proportion of renewables, and with the increasing penetration of heat pumps and electric vehicles, peak demands will be exacerbated and place an additional strain on local and national electricity grids. The use of flexible generation, such as CHP, can reduce network stress at times of high consumption and defer or remove the need for more grid reinforcement.
The use of CHP and other decentralised supplies, is being taken to a new level via local smart grids, such as the Cornwall LEM (Local Energy Market) Energy Storage and Renewables Project, developed by Centrica. This pioneering project will test the use of flexible demand, efficient low carbon generation, renewables and storage, and reward local people and businesses for being more flexible with their energy. It will use connected technologies such as CHP, Solar/PV and battery storage to provide power to businesses and users, as required.
The potential to cluster CHP assets in a decentralised smart-grid or virtual network has previously been demonstrated by research undertaken by ENER-G in partnership with Advanced Digital Institute; Flexitricity; Smarter Grid Solutions and UK Power Networks.
With growing demands on power networks there's an urgent need to stabilise supply and demand and CHP, plus CHP in tandem with battery, heat pumps and other technologies, has a key role to play. But the contribution of embedded generation must be encouraged via a market or incentives that reward CHP developers and owners for their contribution to lower system running costs.
CHP may be a traditional technology, but its valuable contribution to the energy mix remains undiminished. It will continue to have a big role to play in productive decentralised energy production, in helping to stabilise and decarbonise energy supply and in future-proofing its security.
Chris Marsland is Head of Cogen Product and Technology for ENER-G, part of Centrica plc. He chairs the Building Forum of the Association for Decentralised Energy, and is Chair of the Technical Committee for the Association of Power Generating Systems. He is also a Fellow of the Institution of Engineering and Technology (IET).