Beacon Energy, a non-profit making company, was established with the objective of promoting public awareness of global warming and to encourage the reduction of CO2 emissions. West Beacon Farm features many different interlinked renewable energy technologies and enables Beacon Energy to be virtually independent from the national grid and fossil fuels. Each technology feeds its energy into a common dc bus via Unidrive SP ac drives from Control Techniques; more Unidrive units feed all on-site single- and three-phase electricity needs.
“We chose Unidrive because of its versatility,” explains Loughborough University PhD research student, Matthew Little, who has been heavily involved in the development of the integrated system. “We needed drives with a particular mix of features – on-board programming, high speed communications, four-quadrant control – and a supplier who would provide us with exceptional support throughout the project. Control Techniques loaned us drives and other equipment, helped us with design and programming and have been on hand to help at each stage.”
Whittle Hill Farm Buildings, the home of Beacon Energy, and West Beacon Farm, the family home of Professor Tony and Angela Marmont, together form the test-bed for renewable energy in almost all its forms – wind turbines, photovoltaic panels, a ground-source heat-pump system, a hydrogen energy storage system incorporating an electrolyser, storage tanks and two fuel cells, a combined heat and power (CHP) unit powered by propane, solar water heating and two water-powered generators (not yet connected into the dc bus).
Every aspect of the site looks towards conservation, from the use of spring and rain water, septic tanks and composting toilets, high levels of insulation and creative use of natural light and passive cooling in summer. Not surprisingly, the site provides research opportunities for the renewable energy centres at Loughborough, De Montfort and Nottingham Universities and there is a heavy programme of educational visits for schoolchildren of all ages.
Control Techniques has supplied a total of 14 drives to West Beacon Farm, nearly all of them Unidrive SP units fitted with a programmable application module to give on-board programming and CT-Net high-speed networking for data collection and diagnostics. Data is fed into a PC running LabVIEW, which interfaces with CT-Net and monitors every aspect of the system, helping to analyse the effectiveness of the different technologies. “We’ve used Control Techniques’ toolkit, SyptPro, for programming all of the drives and found it to be very straightforward,” adds Mr Little.
A 37kW Unidrive works in four-quadrant mode and is the only link to the mains electricity supply. This has two main functions; to maintain the dc voltage and to export excess generated power back to the grid. “In practice, we use virtually no mains power at all,” says Mr Little, “but it is there just in case.”
Two wind turbines drive 25kW/415V three-phase induction generators that feed power to the dc bus via 30kW Unidrive ac drives. The system is set up so that, at a pre-determined generator speed, the drives synchronise and connect (catching a spinning motor/generator), set the motoring current to zero and start to generate at 50Hz, feeding power to the dc bus. If, after a set time, the turbines are not generating power, the drives close down again. These turbines have been installed for nearly 25 years and have generated power for around 20% of the plated capacity of the units over that period.
Four solar arrays contribute a further 6kW at 120V and the Totem CHP rig, which operates on heat demand, adds another 15kW via a Unidrive SP, as well as providing 38kW of heating for the Marmonts’ house.
The energy storage system comprises a high energy density 20kWh nickel sodium chloride battery at 620V and an alkaline electrolyser that produces clean hydrogen that is stored in 48 high-pressure (137bar) tanks, giving a further 4MWh of energy storage. This hydrogen is used, as required, in two proton exchange membrane fuel cells that, together, produce 7kW of power via power converters to the dc bus.
A reverse-osmosis rig filters rainwater for supply to the house and electrolyser and is supplied by pump driven by a 1.5kW Unidrive SP. A5 kW Unidrive SP controls the compressor pump that steps up the hydrogen pressure from 25 to its storage pressure. Two 12kW Unidrive SP drives supply both the single-phase supply to the Marmonts’ house and the three-phase supply to the helicopter hanger and farm machinery, whilst a 4.5kW Unidrive SP drives the heat pump, which extracts heat from the nearby lake to supply the heating system for the house (this 4kW pump generates 10kW of heat). Unidrive units also control pumps for the water supplies to the house, the hanger and the fire prevention system and further drives provide power for the winch and general amenities local to the wind turbines.
West Beacon Farm has now become one of the world’s best examples of renewable energy in practice. The site demonstrates how integrated renewable energy system, combined with other sustainable practices, can form an effective and reliable independent network. Readers wishing to learn more about this project should visit www.beaconenergy.co.uk
“We have been supported throughout by many suppliers,” Mr Little concludes, “and Control Techniques’ contribution, in particular, has been crucial throughout.”