Energy Efficiency in Power Generation

Power generation is the main source of energy consumption and also the fastest growing. This growth trend is expected to continue based on Exxon Mobil estimates.

Our research indicates that actual power generation capacity will be the biggest constraint to growth in the sector in the foreseeable future rather than fuel supplies, based on current generation capacity, planned generation capacity and historical and projected electricity demand. Despite a drop in electricity demand in 2008 and 2009, global electricity generation has increased every year since 1990.

With that in mind, a large amount of new power generation capacity will be installed in the future to meet growing demand. To an extent, energy efficiency is one way to defer the need for the construction of new power capacity and is more economically viable than the installation of renewable or non-renewable power capacity.

Energy efficiency for a conventional power plant is measured as the inverse of heat rate, which is the amount of energy generated in kWh per unit of fuel heating value measured in Btu (British Thermal Units).

It is estimated that 7 to 15% of energy produced is used in auxiliary systems in the power generation plant. These auxiliary systems are known collectively as ‘balance of plant’, which consumes electrical energy, including:

  • Drive power components, for example pumps, fans, motors and other power electronics such as variable-frequency drives for fuel handling, furnace draft and feed water pumping;
  • Electrical power conversion, protection and distribution equipment such as power transformers and low- and medium-voltage equipment; and
  • Instrumentation, control and optimisation systems for example boiler turbines and other control functions.

Drive power components are being increasingly used to meet mandatory pollution targets in order for power plants to use variable fuels and to improve the performance of aged plants. This includes the use of precipitators and sulphur dioxide scrubbers, additional cooling water pump capacity to minimise heat loss and a move from mechanical drives to electrical motors to drive auxiliary power.

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