Celling the hydrogen economy
The largest and best known fuel-cell installation in the UK is at Woking, and was the first CHP and photo-voltaic system in the UK. The Pool in the Park project combines fuel-cell and conventional CHP systems with photo-voltaic panels to produce heat for space heating, swimming-pool water, domestic hot water for showers and electricity distributed over private wires for the whole leisure complex — which also includes the Leisure Lagoon and Leisure Centre. Surplus electricity is exported over the local distribution network to other customers.
The future is a hydrogen economy, and good old CHP could lead the way to a new way of producing and distributing power around the UK.For anyone who has dismissed combined heat and power as a technology whose time came and went, it is time to sit up and take notice. Allan Jones, the man who created a CHP revolution in Woking and is now the chief development officer for the London Climate Change Agency, says the future has CHP stamped all over it: ‘Fuel cells, and the hydrogen economy derived from renewable fuels, is the only technology that can meet the UK’s future electricity, thermal and transport energy needs.’ Fill the gap
The Government seems to agree with this comment, and has committed itself to a target of 10 000 MW(e) from CHP sources by 2010. However, Phil Jones, chairman of the CIBSE CHP Group speaking at a recent conference, said, ‘The Government has already said that it won’t reach this target, so we need to fill the gap.’ The question is whether fuel cells lead the way to a UK powered by hydrogen? Fuel cells are part of the CHP group of technologies, providing electricity and heat (with water as a by-product). A fuel cell consists of two electrodes sandwiched around an electrolyte. Oxygen (or air) is passed over one electrode (the cathode) while hydrogen passes over the other electrode (the anode). This process generates electricity, water and heat. Typically, fuel cells generate electricity in the range of tens or hundreds of watts. To produce higher voltage and current, cells are arranged in units known as stacks. When supplied by hydrogen, fuel cells emit no carbon dioxide. However, hydrogen is not readily available, so existing fuel cells are often fired on natural gas, with a reformer placed before the cell stack to turn hydrocarbon fuels into hydrogen. This reduces the efficiency of the fuel cell, and also produces other waste gases. Biomass can be used to fuel the cell with methane, again using a reformer in the system to create hydrogen. Many benefits
Despite these disadvantages, the fuel cell offers many benefits. It is particularly useful in the UK, where 70% of the country’s non-transport energy needs are thermal. While CHP produces both heat and power, renewable sources of energy such as wind and solar produce only electricity. It has no moving parts, and is therefore relatively low maintenance and produces very little noise. Even without pure hydrogen, fuel cells offer high efficiencies with very low carbon-dioxide emissions. However, using fuel cells is not always straightforward. The UK’s largest and best known fuel-cell installation is at Woking. This was the first CHP and photovoltaic system in the UK. At the CIBSE CHP Group conference Allan Jones and Martin Fry, chairman of ESTA and vice president of the Energy Institute, revealed some lessons they had learned from working together on the Woking project. Martin Fry pointed out: ‘The economics of fuel cells depend on use of all the heat produced. The more heat that can be used, the better the figures on fuel cells stack up. Sizing of the equipment is important, but the part-load performance of fuel cells is very good — much better than rotating machinery. Also, as electricity production falls off, you do get more heat so you don’t lose out totally. However, electricity is the more valuable commodity.’ Martin Fry also highlighted some key challenges for fuel-cell projects. ‘When considering installation of fuel cells, remember that the cost at factory gate and installed costs can be very different. For Woking, the cost of the equipment itself was around £650 000, but installed costs were £1 million. The additional costs were shipping, insurance, import duty, training for on site staff and commissioning.’ Running the system
Another issue for Woking was lack of information about running the system. ‘The annual maintenance guidance was very poor, and at Woking the technical team wrote its own manual. We budgeted £20 000 for annual maintenance, but we spent £35 000. I would also advise avoiding too many shutdowns on the fuel cells, as this causes more degradation of efficiency. It also uses more nitrogen, which is used at start-up and shutdown to clear pipes of excessive hydrogen, for safety reasons,’ Martin Fry explained. One major challenge was current practice in the power industry. Allan Jones commented: ‘The regulatory regime is a nonsense, and a barrier against development of these new technologies, to protect existing suppliers.’ At Woking, he overcame such difficulties by installing the first local-authority private wires system. ‘We wanted to avoid issues with the major suppliers.’ In spite of teething troubles at Woking, Allan Jones is determined that CHP and fuel cells are the way forward, and he is now working with Mayor Ken Livingstone, who has said that he wants to replicate the achievements of Woking ‘on London’s world-city sized stage’. Allan Jones says: ‘The scale of London could make CHP more economically viable. We want London to be the European CHP and fuel-cell centre. In London, we could make fuels cells part of the waste cycle, as our landfill is rapidly running out. We could use organic waste to produce hydrogen.’ Allan Jones is not the only advocate of the hydrogen economy and CHP. Logan is a US company which operates and maintains 12% of the world’s fuel-cell capacity. Director John Lidderdale agrees with Allan Jones’s view: ‘We are aiming for the virtuous circle of electricity generation. A digestor gas system powers the fuel cell with biogas, while the heat output of the fuel cell is used to drive the digestor process.’ Logan reduces risk for its clients by guaranteeing its fuel-cell installations for 10 years. Trigeneration
In Germany research is now under way into trigeneration — fuel cells which can produce electric power, heating and cooling. German company MTU CFC has developed a HotModule which is a high-temperature fuel cell which can also produce its own hydrogen within the fuel cell itself. Again, the long term goal is to power the equipment from waste. For Allan Jones, a vision of the hydrogen economy starts with a fundamental change in how our power is currently distributed. ‘In environmental and sustainability terms, the more local discrete, private wire, networks interconnect together, the more a city like London becomes sustainable in energy. If other towns and cities did the same thing, there would be no need for large centralised power stations and the National Grid. Overlapping local island generation networks would be the future grid.’ Such developments would lead to an entirely new kind of power network: ‘Embedded generation, such as CHP and other renewables, is capable of providing all the UK’s energy needs. There should be a progressive move towards this goal in parallel with the existing national grid, until it was no longer needed’ Footnote
The speakers were presenting at the CIBSE CHP Group conference, ‘Fuel cells for buildings’ (www.cibse.org/chp). Further discussion of the future of fuel cells will be taking place at the Building Services Event at Earls Court in London on 23 and 24 November.