Power Station Disputes

Features of a power station

Contact: Dr John McCullough, Cadogans

Introduction

Power stations take years to plan and construct and the potential for disputes arising is considerable; over the years Cadogans has dealt with many disputes relating to numerous power stations. This article describes the basic features of a power station.

What is a power station?

A power station is an engineering complex for generating electrical power. The most common, in the UK at least, convert thermal energy obtained from fuel into mechanical energy in the form of steam which, in turn, is converted to electrical energy via a steam turbine and generator. Not all of the thermal energy can be converted into electrical energy.

Thermal power stations use the following kinds of fuel.

• Fossil fuel, i.e. coal, oil, gas, lignite etc
  
• Nuclear, in which the heat to generate steam comes from a nuclear reactor.
• Geothermal, using heat extracted from underground rocks.
• Waste, in the form of municipal solid waste or waste heat from an industrial process.

Diagram of a power station

Electrical power can also be generated from renewables. Wind, wave and river flow can all be used to drive a generator. Solar radiation can create electricity directly via photo-voltaic (PV) cells.

Whilst steam turbines account for most of the electricity generated there are also gas turbines, and internal combustion engines. Here the fuel burns and the combustion causes rotation of mechanical parts which turn a generator.

Both gas turbines and steam turbines (using the waste heat from the combustion) can be integrated into a combined cycle plant. This gives greater efficiency of conversion of fuel to electricity.

Typical energy efficiencies for thermal power plants are low being in the range of 30 to 40%; combined cycle plants are better at around 50 to 55%.

How does a thermal power station work?

In fossil fuel plants the thermal energy is obtained from the fuel by the process of combustion in a water tube boiler. The boiler converts the water into steam at high pressure, which is conveyed to the steam turbine via steel pipe work. The electricity generated is either exported via cables to the national grid or for local use.

The fuel has to be treated and conveyed to the combustor e.g. a coal or oil burner located at the boiler. The water to be converted into steam has to be high quality demineralised water which is produced at a water treatment plant and then conveyed to the boiler via pipes and tanks.

The thermal energy which cannot be converted to electrical energy is dissipated to atmosphere via a cooling tower or a river or the sea.

The combustion products (gases) are discharged to atmosphere via the chimney. Depending on the fuel used, complex cleaning equipment, e.g. flue gas desulphurisation (FGD) plant may be required.

Diagram showing components of a power station

To enable the power station to function correctly it has to be controlled. The automatic control system is intricate and complex consisting of electrical, electronic and pneumatic components comprising cables, wires, piping etc. These sense temperature, pressure, flowrate, condition, alarms etc and send this information back to the main control centre. Large power stations have control centres that are continuously staffed although many of the functions are automatic.

What are the disputes?

For any given power station the disputes may be 1) commercial or 2) technical or 3) both.

1) Commercial disputes involve money but not engineering issues; although they could be underpinned by such issues. If the power station or some of its components costs more than planned, there is a dispute as to quantum, even though the station may work as intended. If the power station took longer to construct than planned then there will be a dispute as to time, which inevitably means money, and programming, even though the finalised station may be performing as intended. Disputes about delay often have engineering issues lurking in the background.

2) It follows from the earlier description of a power station that there are hundreds of potential technical disputes; some examples are given below.

• Component failure e.g. the turbine or boiler undergoes catastrophic failure.
• The boiler and/or fuel handling system cannot cope with the fuel as specified and/or provided.
• The design is wrong and the plant cannot produce the steam or electricity as intended.
  
• The flue gas cleaning or treatment plant fails or is defective and cannot meet the emission requirements imposed by the environmental policing authority.
  
• The water treatment plant does not work properly which leads to component failure and/or damage by corrosion.
• The electricity produced is not of the required quality (voltage/frequency).
• The amount of fuel and/or demineralised water required to produce the electricity exceeds that specified and planned for in the cost life cycle analysis.
• The complex control system does not function as intended.
• The chimney cannot discharge and disperse the glue gases as intended.
  
• The cooling towers produce too much water vapour, which is a visible pollutant, exceeding the limits imposed by the environmental policing authority.

The above examples are but a few (and relatively major) of the literally hundreds of technical things that can go wrong.

3) Any technical problems during construction and commissioning will cause delay and increased cost. Any that occur after the commissioning phase when the power station is in use will result in disputes about money for remedial work or replacement. In addition, such work may mean the station cannot function and there would then be a dispute as to the amount of downtime with its cost and programming implications. So, many power station disputes have both commercial and technical components: the worst-case scenario.

(This article was first printed in "Your Witness" magazine (Winter 2008-09), www.your-witness.co.uk)