Collaborative Research & Development Case Study

Cool Way To Slash Energy Consumption In The Food Industry

Supermarkets and food processing plants could slash their energy costs by over 30% and reduce greenhouse gas emissions by 25 50% using green technology demonstrated by a collaborative research and development project.

Feasibility trials of a new approach to the use of combined heat, refrigeration and power (CHRP) show that it could nearly double the levels of energy efficiency currently achieved in the industry. Potential savings could be highly significant to the economy as around 5% of total UK energy consumption is accounted for by retail food outlets alone.

There is growing interest in the pioneering research among leading supermarkets, particularly in order to reduce greenhouse gases. The Bond Group and Safeway Stores were part of the project consortium, which enabled industrial partners to work with mechanical engineering experts at Brunel University.

Objectives
All those frozen meals, chilled dairy products and cool cucumbers at the local supermarket currently come at a high price in energy terms. Even state-of-the-art stores use energy relatively inefficiently, and refrigeration accounts for around half of their total energy consumption. Food processing plants are even more ‘energy-hungry' and represent as much as 10% of total UK consumption.

The collaborative research project set out to demonstrate how a new approach to the use of combined heat, refrigeration and power (CHRP) could provide a solution that would cut costs and benefit the environment. Safeway joined supermarket refrigeration specialists Bond Retail Services, working with a mechanical engineering team led by Professor Savvas Tassou at Brunel University.

Solution
The use of CHRP avoids the inefficiency of generating electricity at power stations and distributing it over the national grid. Instead, heat, refrigeration and electricity are produced on site by small gas-turbine generating units. The research project investigated the use of these micro-turbines. It studied how waste heat could be recovered from the exhaust and fed to an absorption chiller to meet both frozen and chilled food requirements.

A feasibility study was carried out to test the performance of the absorption plant and show whether it could achieve the output that would be needed at an intermediate temperature of -12 Deg C.

Results
Results of the feasibility study showed that the new green technology could achieve the required performance and enable the industry to make dramatic improvements in energy efficiency. The research demonstrated that an absorption plant would be able to deliver all the refrigeration needed at a typical large supermarket. It would provide chilling at two temperature ranges – one for frozen food and another for chilled food such as milk, dairy products and meat.

Three to five micro-turbines would be needed at each store. The units capture heat generated in the production of electricity and are claimed to increase overall efficiency from around 38% to around 76%. According to the project team, the process lends itself perfectly to supermarkets. At a typical store, the technology makes it possible to double thermal efficiency and reduce carbon emissions by half.

Researchers claim the commercial system will further benefit the environment by eliminating refrigerant leakage as well as saving energy.

The results are regarded as very encouraging. The technology is fully transferable and can be applied to all kinds of applications including cold stores, food-freezing factories and freeze-drying plants. When freezing vegetables such as peas, for example, producers will be able to use even more waste heat in the blanching process and make further gains in thermal efficiency.

There will be significant potential export markets for the technology, which is based on the use of micro-turbines produced by the UK company Bowman Power Systems Ltd and a special type of absorption chiller now under development at Brunel University.

As many as 2,500 supermarkets and an estimated 1,000 refrigerated food process plants could benefit from the research if plant is replaced with CHRP in the future, helping them to meet efficiency targets set out in the Government's Energy White Paper in 2003.

Growing interest is expected as the White Paper is calling for major improvements in environmental sustainability, reliability, affordability and competitiveness. It sets a target of a 60% reduction in carbon emissions by 2050. Firms are being encouraged to adopt carbon trading policies and meet Good Quality CHP (Combined Heat and Power) targets to achieve an environmentally sustainable energy future.

In two years time the project team expect to have achieved a 50% reduction in energy usage through the CHRP technology, making significant progress towards meeting the White Paper targets. With carbon trading budgeted at €12.5 per tonne, considerable scope to drive costs down is anticipated, particularly as exemption from CCL (Climate Change Levy) should also apply.

The Last Word
Following the success of the initial project, a second phase of research and development has now been given the go-ahead. Work will focus on design of a low temperature absorption chiller and associated heat exchangers, which will also be able to provide space heating and water heating for food processing plants. A mini-supermarket will be built at Brunel University to test the complete CHRP system. An application will be made to patent the technology, which could be launched commercially by 2007.

Project leader Doug Marriott, who has driven the project, explained why the collaborative research had been so important. ‘Retail food supermarkets are very green companies but their core business is food retailing, not saving energy,' he said. ‘We would never have managed to get this project off the ground without the support we received from Defra. The project officer gave plenty of guidance, enthusiasm and encouragement, which helped us to achieve our goals. The programme shows vision and it is a fantastic initiative for British industry and academia to combine their knowledge and resources.'

Source: DTI Technology