What makes an outstanding CHP/district heating scheme? These four winners from the UK both answer the question and illustrate how the UK CHP sector is developing there. Note the emphasis on no-capital finance, the provision of cooling as well as heat and power, and the growing role of biomass.

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These zero carbon homes are heated using a low-temperature district heating system

Four CHP and district energy projects and their developers, together with one influential individual, have won the five categories in the fourth UK CHP Association annual awards. The awards were presented at the CHPA Awards dinner in the City of London in November 2010.

The winner of the Innovation award was Scottish and Southern Energy, for its district heating scheme installed to serve the Greenwatt Way zero carbon housing development comprising 10 homes in Slough. The Community and Residential sector award went to ENER-G and ESP Projects, for the installation of a 10 kWe Yanmar micro-CHP unit at a sheltered housing scheme in Newcastle upon Tyne.

The winner of the Industrial and Commercial award was GlaxoSmithKline and Centrax, for a recently implemented trigeneration scheme that provides heat, power and cooling to a GSK soft drinks plant in Gloucestershire. In the public sector category, the winner was, again, ENER-G for its new trigeneration scheme installed at Solihull Hospital.

Finally, the 2010 CHP Champion was Chris Matthews from the Co-operative Bank. Matthews has an outstanding record of delivering funding for CHP projects over many years.

‘The quantity and quality of entries we received this year was extremely impressive,’ said Graham Meeks, the CHPA’s director. ‘The sector is truly stepping up a gear in demonstrating what is deliverable in terms of cost-competitive decarbonization.

‘We also saw increasing innovation, in the use of renewable fuels and in the integration of CHP and district heating with other technologies, demonstrating the growing value that the sector brings in our changing energy system. For those who are prepared to innovate and push the envelope, the prize of greater efficiency, reliability and cost savings are there for the taking.’


Innovation: Scottish and Southern Energy for Greenwatt Way

This is an innovative development of 10 zero-carbon homes heated via a district heating scheme. The heat for the district heating scheme is generated either from an air source heat pump, ground source heat pump or biomass boiler. All of these heat sources can be supplemented with 20 m2 of solar thermal panels.

The houses have sufficient solar PV panels to power the heat pumps and meet all the domestic electricity demands. To maximize the operating efficiency of the heat pumps, the district heating system has been designed to operate at a flow temperature of 55°C and a sub 35°C return temperature. The energy centre has a large thermal store with multiple connections to enable layered charging from the heat pumps, at a range of temperatures – this maximizes the coefficient of performance (COP) of heat pumps and enables maximum benefit to be realized from the high potential temperatures from the solar thermal.

The district heating network uses steel twin-pipe to minimize heat losses. A large, layered thermal store is 

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The Wilton International CHP plant, fuelled with locally sourced biomass, was highly commended – see page 48

used to maximize the benefits of solar thermal and heat pump performance. Adding flexibility and enhancing optimization of the scheme as a whole, the thermal store enables balancing of the temperature variance between different technologies and ensures continuity in the efficient supply of hot water through the district heating network.

The homes have been occupied since September last year by Scottish and Southern Energy staff and residents from Slough Borough Council. Smart metering is being used for heat and electricity and a rigorous programme of monitoring is planned of house heat, electricity, main water, recycled water demands; PV generation; heap pump, biomass and solar thermal performance.

The scheme itself and the related monitoring programme provide a significant learning opportunity for how heat pumps and solar thermal technology can work in combination with district heating. This is complemented with equally valuable insight into low-temperature district heating and actual space heat and water heat demand of zero carbon homes.

Community & Residential: ENER-G and ESP for Tyneside Cyrenians

A 10 kW Yanmar micro-CHP unit was installed, by ESP Projects, and is now maintained by ENER-G, at Elliot House in Newcastle upon Tyne, a sheltered housing scheme for vulnerable adults operated by the Tyneside Cyrenians charity. The unit was provided free of charge by Yanmar, the Japanese manufacturer.

This was the first installation in the UK of the 10 kW unit, which is now available commercially, following trials of two other Yanmar units. The unit at Elliott House provides heating, hot water and electricity to the main accommodation block, acting as the lead boiler and reducing the requirement for electricity imports from the national grid.


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The gas turbine-based trigeneration plant at GlaxoSmithKline’s plant in Gloucestershire

The unit runs on natural gas and can generate 10 kW of electrical output and 17 kW of thermal output. Over the course of its operation to date, the unit provided primary energy savings of 11% and has led to a 35% reduction in site carbon dioxide emissions and also a 42% cost reduction in energy spend for the charity.

Industrial & Commercial: GlaxoSmithKline and Centrax for Royal Forest Factory

Centrax installed a CHP plant operating in trigeneration mode to provide heat, power and chilled water to a new operation at GlaxoSmithKline’s (GSK) plant in Gloucestershire, which produces Lucozade and Ribena. The scheme uses a 5.4 MWe single cycle gas turbine allied with a heat recovery steam generator supplying heat for pasteurization. An integrated feedwater economizer and plate heat exchanger are used to minimize heat losses from the system. Operating as a trigeneration scheme, it incorporates an absorption chiller plant for full use of all waste heat.

The net result for GSK is a 19% decrease in site energy costs, alongside an 8% reduction in carbon dioxide emissions. The plant is linked up to an intelligent load-shedding system which, in the event of loss of either the national grid supply or turbine, will shed the site’s non-essential load within 100 milliseconds to ensure the site’s critical loads remain energized.

As part of a wider large-scale investment project by GSK, the scheme has helped secure the long-term future of the site and the 500 plus jobs linked to its operation.

Public Sector: ENER-G for Solihull Hospital

ENER-G installed a £5.7 million trigeneration scheme at Solihull Hospital, which is operated by the Heart of England NHS Foundation Trust, in May 2010 at no capital cost to the trust. Replacing an old, inefficient steam heat supply system, the new system provides electricity, steam/hot water for heating and chilled water for air conditioning. The efficiency benefits realized as a result of this change have delivered emissions savings in the order of 190,000 tonnes of carbon dioxide per annum.

The natural gas-powered unit, providing 770 kWe to the site, was commissioned last summer. The project also involved a strategic refurbishment of the hospital’s electricity, heating and cooling infrastructure, cutting back on energy costs while increasing interior climate comfort for patients, staff, and visitors.

Champion: Chris Matthews, Cooperative Financial Services

This award recognizes an outstanding contribution to the advancement of CHP and/or district heating and cooling in the UK.

Chris Matthew’s involve-ment in the CHP and wider distributed energy sector goes back to 1998, when the Co-operative Bank acted on his recommendation and direction in launching its own Climate Change Strategic Policy. From this point Chris began to fund CHP installations and some 12 years on Chris now heads up the bank’s Renewable Energy and Asset Finance team, which has a mandate to provide £600 million of funding into the renewable energy and CHP sectors.

Chris remains passion-ate about the social problems that CHP can address and, in particular, fuel poverty. He has been responsible for supporting energy service company (ESCo) projects that introduce CHP and district heating networks (such as Aberdeen Heat & Power) that help address fuel poverty and improve the quality of life of many disadvantaged people.


Highly commended entries

Innovation: Cogenco for Cannington Cold Stores

Cannington Cold Stores operates a 9000 pallet facility in Bridgwater, Somerset, that serves a large number of food producers. It provides a range of frozen, chilled and ambient storage facilities. From here food goes through the process of splitting, picking, packing and distributing throughout the UK, Europe and worldwide. A by-product of the operational activity is food waste.

Cogenco installed a biogas-fired CHP system to meet site energy needs with the capability to export electricity to the grid when appropriate. The scheme is fuelled by food waste produced by the facility, which is fed into an anaerobic digestion process. Heat and power is generated by four operating CHP units totalling 1.3 MWe, and heat from the CHP units is fed into the digesters to sustain the biogas generation process. The scheme has cut on-site energy costs by 94%, saving 1500 tonnes of carbon dioxide. Two more CHP units are being planned to further expand the generation capacity.

Using the food waste to generate biogas means that landfill is avoided, which reduces potential methane damage to the atmosphere. Government figures suggest that there are 12-20 million tonnes of food waste per year in the UK, with a further 90 million tonnes of slurry that could be utilized to generate biogas suitable for CHP – potentially generating 7% of the UK annual electricity demand.

Industrial & commercial: Sembcorp Utilities for Wilton International
Sembcorp’s Wilton International site is one of the UK’s most important manufacturing locations. In 2007, Sembcorp commissioned a 35 MW biomass-fired power station to sit alongside its existing 194 MWe natural gas-fuelled CHP plant. The scheme uses a variety of wood fuels, sourced from the North East and surrounding regions, and employs recycled waste wood, forestry residues and sawmill co-products.

In 2009, the company decided to build on its already impressive sustainability credentials by investing an additional £5 million to convert the biomass plant into a biomass CHP unit. The conversion will allow the plant to recover and reuse the heat it generates for the benefit of customers at the Wilton International site.

The green credentials of the Wilton International site, with the added cost benefits of highly efficient energy generation, serve as a major attraction to new investment. Examples include Europe’s largest biofuels plant now located at Wilton; a rapidly expanding plastics recyling operation; and Europe’s first large-scale tyre pyrolysis plant, which turns used tyres back into carbon black, steel, gas and oil.

Commitment to developments such as the conversion of the biomass plant into a CHP, are giving the site a growing reputation as a centre of excellence for green industry – crucially important following the closure of a number of chemical industry manufacturing facilities in recent years. This in turn is helping make Sembcorp’s business, employing 400 people, plus hundreds of supply chain jobs dependent on its operation, more sustainable in the long term.

Public sector: Hill Dickinson LLP for Royal Free Hospital
Hill Dickinson helped ensure successful delivery of a substantial trigeneration system at the 740-bed acute care Royal Free Hospital in Hampstead, London. The scheme, based on a 5 MW natural gas-fuelled CHP unit, is expected to deliver savings of over 7600 tonnes of carbon dioxide per annum. The cost savings secured for the NHS Trust will also total many millions of pounds over the course of the contract.

As a trigeneration scheme, the CHP unit, twinned with an absorption chiller, will meet all the hospital’s heat and cooling needs, along with a large proportion of its demand for electricity. The relevant boiler is also constructed to enable expansion, should the hospital have the opportunity to act as a hub in any future district heating scheme development.

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