Steve Hodgson Editor, COSPP
CHP and decentralized energy schemes are necessarily flexible, serving variable on-site loads as opposed to merely pumping power into a grid and, in the case of CHP at least, providing energy in two (sometimes three) different forms. The ability to operate in flexible, load-following patterns is essential.
Add district energy and the situation becomes more complicated. Birmingham in the UK is home to a major trigeneration (heat, power and cooling energy) district energy scheme that has been growing since the feasibility study was carried out in 2003. The gas-fuelled scheme sends low cost heat energy and chilled water, via underground pipelines, and, via à¢€Ëœprivate wires,à¢€â„¢ electricity to client buildings across the city. Here, the aggregation of many different loads helps to simplify the operation of the central plant à¢€“ the story is told by Cofely District Energy on page 35.
Two more features in this issue take a look at the furthest ends of the size scale for decentralized energy. On page 29, researchers at Delta Energy & Environment discuss the prospects for domestic-scale generation to meet the almost impossibly variable domestic energy loads in Europe. They conclude that micro-CHP is likely to stay ahead of both solar photovoltaic and micro-wind technology, in terms of connected generating capacity, at this size.
Meanwhile, on page 50, Alstom describes its combined cycle cogeneration plant designed around maximizing the flexibility of energy generation to meet large-scale, but independently variable, heat and power loads, whether these are for industry or district heating schemes. The examples mentioned serve an industrial facility in Germany, a district heating scheme in Russia and, unusually, an LNG import terminal in the UK. Operational flexibility is demonstrated in each case.
A second theme this issue is, once again, the growing use of biogases to fuel cogeneration schemes à¢€“ as featured in three of the four project profile articles. The first features a US hospital using both organic brewery wastes and landfill gas to fuel its CHP schemes; the second, a farm in Germany that grows grain and maize and uses liquid and chicken manures to create biogas to fuel an engine-based CHP scheme; and the third is a US wastewater treatment plant that imports additional organic wastes in order to maximize the biogas feedstock for its CHP schemes.
Natural gas will remain the major fuel source for CHP for quite some time to come, particularly if supplies of pipeline gas are augmented in some places by new LNG imports and by new shale gas finds in others. The pressure to use precious natural gas, whatever its source, efficiently, rather than in electricity-only power stations, can only increase. But the use of biogases produced from wastes and organic by-products in CHP schemes, therefore at maximum efficiency, is a particularly elegant use of resources.
Steve Hodgson Editor, COSPP
PS. The other news this month is that COSPP has a new, brighter and more comprehensive website that covers the whole range of CHP/cogeneration, decentralized and on-site energy matters world-wide. The address is the same à¢€“ go to www.cospp.com à¢€“ to read news items, to access and subscribe to the print edition, see the COSPP archive, sign-up to the monthly e-newsletter and, most importantly, comment on what you see and join the debate. Just log in to participate and join the biggest CHP/cogeneration community there is.