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- 21 November 2007 -

Filtration in the power generation sector

Ken Sutherland looks at the use of filtration and related separation equipment in the generation of electrical power for the power supply utilities and other large users.

The power generation sector covers the production of electricity by central generating stations, for local distribution, or for feeding into a national grid for wide distribution. The same equipment, largely, is used in power stations set up to supply a single factory, or a captive system, such as a railway network. The distribution of gas is also covered - which, while having little interest for the full range of separation equipment, could become an important market for the gas separation range of membrane processes. As understood here, the sector does not include the extraction and preparation of the fuel used in the generation process.

The production of electric power mainly involves the release of energy from a fuel (coal, oil, gas, nuclear or accumulated wastes) and the use of this energy to generate electricity, employing rotating machinery. The actual generation step is, of course, a dry process, without need for solid/liquid separation equipment. However, important uses exist in the energy release stage, for example in the production of the pure water required as a boiler feed, and in the dewatering of sludges formed in some flue gas treatment processes. More and more stringent requirements are being placed on water quality, and membrane processes have an important part to play in this application.

The sector is a very important one to the solid/gas component of the separation equipment market - and filters, in turn, are vital to the successful operation of power generation. All gas turbines rely on their intake air being clean - i.e. filtered - and most generating system exhausts need some kind of treatment before they can be discharged to the atmosphere.

In contrast, renewable sources of energy, when used to generate electricity, have very little use for solids/liquid or solids/gas separation equipment. The wind turbine produces electricity directly for local use or acceptance by the grid, as do hydroelectric schemes on land, wave or tidal systems at the coast, and even the planned solar thermionic or photo-voltaic systems in hotter regions. These renewable sources are intended to become a significant part of the power generation sector, but just how significant is still a matter for conjecture.

Filters are vital to the successful operation of power generation.

Talk of renewable energy sources inevitably turns to the "hydrogen economy", although much comment about it tends to ignore the fact that hydrogen is an energy vector and not an enormous untapped source - the production of hydrogen requires more energy input than can be released by its combustion. Its production is not a problem - the petroleum refineries have been doing it in large quantities for decades - we just need to be able to produce it without consuming equivalent quantities of fossil fuels. The processes to do so are there, but they are not yet viable.

From consideration of hydrogen, it is a short step to the fuel cell. A very interesting component of the power generation sector lies in the small-scale generation of power by the use of fuel cells - a technology whose day has been about to come for over 50 years (or the 160 years since its invention), but which really does now seem to be on the verge of practicality. In the form of a road vehicle engine it is about to reach the market in considerable numbers, and while its use for central electricity generation is some way off, electrically driven membranes will have a good market once this development is complete.

The industry

Electric power is fairly easily moved over long distances (as is now done between France and several of its neighbours), and there is much talk of the possible creation of a single energy market within Europe , a situation that is certainly favoured by the European Union. Considerable investment in better distribution grids is obviously called for, in the light of the major power failures that have occurred recently, in the northeast of the USA, and over the whole of Italy, as well as a smaller one in London.

Most formerly public (i.e. government owned) electricity generating utilities have been privatised - only France now, of all of the major countries, still has state-owned utility companies, although even here the first steps have been taken towards privatisation at least of the gas company. Electricity and gas, which once were provided by separate utilities, are now frequently available from the same company, and there has been a recent trend towards the "total" utility, supplying not only electricity and gas, but also fresh water - and taking care of wastes of all kinds, both wastewater and solid wastes (and even telephone service as well in some cases). Thus RWE expanded rapidly into the water sector (although it withdrew from it almost as quickly), whilst the former British Gas now offers electricity supply and telephones.

This feature of the multi-utility is partly the result of the privatisation of the state utilities - and partly by the deregulation of the energy markets. That the latter step has been a very mixed blessing is apparent from the problems in the USA of an energy crisis in California, and the spectacular collapse of Enron, dragging other similar power companies down with it.

The sector is also much concerned with prices at present, especially in view of the excess of generation capacity that was observable in 2002, followed by a rapid reversal during the hot summer of 2003. The once powerful British Energy was brought to the verge of bankruptcy, almost entirely because of price reductions. The rapid growth in oil prices during 2006 and 2007, culminating in the US$100 barrel in November 2007, is making the whole prices structure very uncertain again.

The power supply market is a complex one, with very differing corporate structures. The USA and Germany have had private supply, in the hands of many suppliers, for the last half century. France, Italy, Spain and the UK, on the other hand, started with state monopolies, and, apart from France, have opened the market up to private purchase. The result was a great deal of ownership transfer, within and across national borders, which still continues: Iberdrola buying Scottish Power to make Europe's third largest utility company; Gdf and Suez finally merging after nearly two years of trying; the two largest Dutch utilities, Essent and Nuon, merging; Spain's largest utility Endesa being carved up between E.On and Enel/Acciona; E.On's purchase of OGK-4 (part of Russia's Unified Energy Systems) and Airtricity, the US wind-power company; as well as the ongoing saga of the KKR/Texas Pacific bid for TXU.

The leading suppliers of electrical generating systems are General Electric, with about one quarter of the world's business, and Siemens and Alstom, with another quarter between them.

The power generation sector is expected to show a filtration and related separations equipment sales volume for 2007 of about US$2.55 billion. This is for central station generation only, and excludes on-site and captive system generation systems, or any small-scale or mobile power generation. The market value is increasing at about 6.2% in real terms.

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