The ceramic fuel cell at the Madeley Centre is no bigger than a domestic washing machine, and runs quietly without vibration. The inverter is fitted to the wall behind.
Since its opening in 2011, the Madeley Centre near Newcastle under Lyme in north Staffordshire has become a byword for adopting low-carbon technology, and can now boast a ceramic fuel cell as part of its energy generation mix. The BlueGen unit was installed in 2013 thanks to a grant of £13,600 from National Grid Affordable Warmth Solutions, and acts like a mini power station, principally generating electricity but also supplying about 200 litres of hot water daily.
The BlueGen fuel cell is classed as a micro combined heat and power (micro-CHP) unit, and is so far the only fuel cell model to receive accreditation for the government's Feed-in Tariff Scheme (FITS). Hence all the electricity generated by the fuel cell earns revenue from the FITS, besides cutting the amount of electricity needed from the national grid. So what is a fuel cell, how does it work, and where does it fit in to the growing spectrum of low-carbon technologies that are available?
How it works
The fuel cell essentially uses the mains gas as a fuel to generate electricity with high efficiency, of up to 60%. And this it can do night and day, 365 days a year (provided there are no power cuts!). It is based not on combustion, but rather an electrochemical reaction. The hydrogen in the methane (from natural gas) and oxygen in the air react with electrodes inside the fuel cell to cause electrons to flow, hence the energy in the gas is directly converted to electricity. An inverter is also required to convert the direct current from the fuel cell to alternating current suitable for supplying the building. Emissions are water and carbon dioxide, plus heat. The heat is recovered and stored in a tank as hot water, suitable for washing, etc.
Pat Callaghan of the Madeley Centre, north Staffs, has helped drive the installation
of a ceramic fuel cell to reduce the building's carbon footprint.
Inputs and outputs?
A single BlueGen unit will generate about 36 kilowatt hours (kWh) per day, which equates to roughly 13,000 kWh annually. To maximize the revenue from the FITS, the unit at Madeley is run consistently at full capacity, which produces about 27 kWh of heat per day. Gas consumption so far averages 66 kWh/day, and the Centre pays a service charge of about £750 per year. The unit's performance is monitored remotely via the internet, to check that everything is working, and to glean useful data.
The Madeley Centre near Newcastle under Lyme is designed to be as carbon-neutral as possible. Besides the fuel cell, it has solar PV and solar thermal roof panels, a ground source heat pump, natural ventilation and a green roof on part of the building.
Costs, revenues and savings
According to BlueGen, the key data from the Madeley unit are as follows:
- Revenue from FITS: £5.48/day = ~£2000/year
- Cost of gas: £2.38/day
- Maintenance charge: £2.05/day
- Savings on electricity bill (@12p/kWh): up to £1500/year (total depends on usage)
The unit supplies roughly 3-4 times the amount of electricity used by the average household, so it is not suitable for single dwellings. It is being promoted chiefly to social housing, multi-occupancy buildings (e.g. apartment blocks) and small businesses, which are relatively heavy users of electricity (in the range 10,000 to 20,000 kWh/year) and can maximize savings on their electricity bills. At Madeley, the unit fits comfortably into the mix of technologies by supplying low-carbon electricity to power the ground-source heat pump responsible for space heating, hence reducing the overall carbon footprint of the building.
Of course, the fuel cell at Madeley currently runs on natural gas, a fossil fuel, so can it be described even as low carbon? The manufacturers counter this by claiming that the high efficiency of generation on site compares favourably with the current fuel mix of grid-generated electricity, which delivers only some 20-30% of original fuel energy to the point of use, given losses at power stations and during transmission. And the unit can be fuelled by methane or hydrogen derived from renewable sources, for example biomethane from anaerobic digestion, which might be an option for certain installations in the future.