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Genset operators switch to natural gas; More costly to buy but much cheaper to run--that sums up the buoyant natural gas-powered sector of the booming genset market. This first of a special two-part series looks at the key issues of versatility and who the suppliers are.

Article Excerpt
THE TOTAL WORLD consumption of diesel- and natural gas-powered generating sets has been estimated at around 400,000 units, worth approximately US$7 to US$8bn. Sets above 1,000 kVA have experienced considerable growth from 2000 onwards with the US clocking up a 50 per cent increase and Europe 36 per cent.

However some 70 per cent of all units are below 1,000 kVA, but value-wise these only represent 20 per cent of the total commercial value. Sets below 7.5 kVA account for 54 per cent of all units. Just four companies account for between 60 to 70 per cent of all Europe's exports in generating sets of all sizes. The market for natural gas-powered generating sets was estimated to be US$512mn in 2005 (above 1 MW).

The percentage proportions between diesel-driven and natural gas-driven generating sets have remained static, although the demand for gas generating sets has increased dramatically over the last 10 years. As an example, in 1998 the orders for natural gas-powered engines for generating sets amounted to 16.8 per cent of all engine orders placed. In 2005 this had remained the same at 16.7 per cent and covers outputs from 1 MW up to 5MW. In quantity terms, gas units have risen from 689 in 1998 to 1416 in 2005.

However with some engine manufacturers, such as Rolls Royce Bergen, nearly 40 per cent of all engines built are now gas fuelled.

The emphasis has been on the larger size of generating sets above 1,000 kW (1 MW). It is estimated that the global market for reciprocating-engine prime-power installations above 1MW is around 17,000 MW--Europe accounts for nearly one quarter. But this figure includes large gas turbines so the diesel, dual-fuel and gas-powered generating market is about 3,000MW, of which one third is driven by natural gas.

The market for generators with diesel engines over 1MW is declining, particularly in Europe, mainly because of exhaust emission requirements. Wartsila for instance say that 90 per cent of their power generation projects above 4MW are gas-fuelled now.

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This manufacturer's range of outputs with gas-powered plant goes from 4MW up to 17MW with the ability to provide power station installations up to 150MW. Business must be booming as orders for gas-powered generating plant show a 33 per cent increase from the previous year.

Sky-rocketing gas prices may curb the rate of present production, but now markets are continuing to open up due to natural gas infrastructure development, and the potential of LNG has yet to be realised.

Engine emissions

Diesel engines are finding it increasingly difficult to meet the most stringent exhaust emissions legislation--especially near environmentally-sensitive places. Turbocharged, lean-burn spark-ignited gas engines provide very low exhaust emissions--typically half that achievable by diesel engines using SCR. Adding a catalytic converter enables the most stringent air quality standards to be met with gas--whereas diesel power, even with a catalytic converter, will be struggling to meet the regulations in sensitive areas.

Therefore gas engine-powered generating sets are making significant inroads into many diesel engine sectors.

Emission regulations are a complex subject. Both the US and Europe have laid down well defined limits for carbon dioxide (C[O.sub.2]), particulate matter (PM) and nitrogen oxide (N[O.sub.2]) on a phased-in time table over the period from 2001 up to 2015. A large number of these regulating limits are already in force. Others such], as the 2007 EU stage II emissions legislation are imminent and yet others are in the pipeline.

The Non-road Machinery Directive 97/68/EC was initially promulgated on 16 December 1997. Although stages I and II were implemented from 2001 to 2004, generating sets as such were not covered by these stages. However, the European Parliament adopted stage II in December 2002 and this applies to diesel- and gas-powered generating sets--but only in sizes of 18kW to 560kW. These regulations became effective in 2007, specifying precise emission standards for CO, HC, (N[O.sub.x])...

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