Orimulsion is a cheap bitumen-based fuel imported from Venezuela by BP Bitor. Both National Power and PowerGen have shown great interest in using it to increase output from their under-used oil-fired power stations. Their plans have been strongly opposed because of the fuel's high sulphur content and the impact of increased fuel imports on the beleaguered British coal industry.
National Power's plans to burn the fuel at stations in Pembroke, south Wales and Padiham, Lancashire ran aground last year when HMIP insisted that SO2 abatement equipment was needed (ENDS Report 216, pp 5-6 ). The company has now closed Padiham, and though it is officially considering its options for fitting flue gas desulphurisation (FGD) equipment at Pembroke, the project appears to have been put on ice.
HMIP has taken a different approach to PowerGen because the company started testing Orimulsion in 1990 - before IPC came into force. The practice was therefore classed as an existing process, and so does not have to comply with new plant standards immediately.
Most power stations were authorised in April, but HMIP held back the Ince and Richborough applications to consider the technical and commercial aspects of Orimulsion. It has now effectively given the fuel's prospects in the UK a new lease of life. According to an inspector, "we could see no justification on environmental grounds for HMIP to ban or severely curtail its use."
Orimulsion has a sulphur content of 2.7-3.0%, considerably higher than the 1.6% average of British coal but similar to that of heavy fuel oils. But HMIP has accepted PowerGen's argument that on other emissions, including heavy metals, Orimulsion is not significantly dirtier than other fuels. The company has compared likely maximum emissions from a 500MW unit at Ince burning Orimulsion or residual fuel oil (see table ).
The IPC authorisations will not lead to any rapid reduction in SO2 emissions from the two stations. HMIP has taken the same approach used for coal-fired plant, for which annual release limits were derived from the official National Plan for reducing acid gas emissions from large combustion plant (ENDS Report 219, pp 15-16 ). Ince will not be allowed to exceed its 1993 National Plan target of 60,000 tonnes of SO2. However, the 360MW Richborough plant can exceed its National Plan limit of 17,000 tonnes by 50% because it is considered less likely to contribute to local air quality problems or exceedences of "critical loads" for acid deposition in more remote areas.
Other conditions may prove more constraining. A ceiling on daily consumption of Orimulsion at Ince will limit the fuel's use to one of the station's two 500MW units. Both stations have been given daily SO2 release limits, and fairly tight limits have been set for particulates.
However, HMIP's upgrading requirements are the most significant aspect of the authorisations. Both PowerGen and National Power have already been told to submit proposals by April 1994 for upgrading their existing stations to new plant standards. The same condition has been attached to the Ince and Richborough authorisations - but by September PowerGen must also submit an assessment of "appropriate sulphur abatement techniques", and fit them by April 1998.
PowerGen's preference is for abatement systems based on lime injection, which may not meet new plant standards but would be much cheaper than full-scale FGD. HMIP is giving increasing weight to economic factors (ENDS Report 222, pp 16-19 ) and may have some sympathy for the argument.
The outcome will depend crucially on PowerGen's overall upgrading strategy. Both generators already have considerable surplus capacity and can be expected, as new gas-fired power stations enter the market and electricity imports increase, to close many existing coal-fired stations rather than pay heavily for upgrading.
HMIP's acceptance of Orimulsion is a further blow to British Coal's prospects as the generators wrestle with difficult decisions over their future fuel mix. In last winter's coal review, the DTI said that it expected Orimulsion imports to drop by 500,000 from existing levels of 1.4 million tonnes per year. However, following the IPC authorisations imports can be expected to hold up easily. The only fly in the ointment is a row between BP Bitor and the Treasury over whether the fuel is eligible for import tariffs - which would make the fuel considerably less attractive.
Meanwhile, it has emerged that National Power's and PowerGen's upgrading plans, which will have profound implications for the UK's future energy policy and international environmental commitments, will not be entered onto the IPC public register. HMIP's advice is that the register regulations do not require such post-authorisation reports to be placed on the register. And it is far from clear that the information will be available under the Environmental Information Regulations 1992 (ENDS Report 216, pp 31-32 ).
HMIP's guidance note on large combustion plant specifies that "the operator should provide the Inspector with a programme for upgrading or closing the plant as part of the application for an authorisation" - where it would have been available for public inspection. However, the generators failed to supply the information in their applications, and it now seems that their plans may remain secret.