Nokian Capacitors Ltd. - Energy savings

COMPENSATION SAVES ENERGY

Generating reactive power at the point of consumption helps energy production and thus saves energy. It frees power plant capacity for the production of active power and reduces losses in transmission and distribution systems. At the same time, there is a higher capacity available for the transmission of active power.

To generate reactive power at the power plant is uneconomical, producing losses in the electricity network. This leads to increased use of primary energy. In transmission and distribution systems, reactive power requires as much capacity as active power.

To increase the efficiency of their performance, electricity suppliers and the owners of transmission and distribution networks have adopted a "reactive power tariff", which encourages consumers to produce locally the reactive power they need, for example with the help of compensation capacitors.

In boosting the production and distribution of electricity, reactive power compensation reduces the need for oversized power plants and distribution networks.

EXAMPLE OF SAVINGS THROUGH COMPENSATION

It is difficult to assess exactly the environmental impact of reactive power compensation, but to get an idea of it let's think of the situation the other way round: What happened if all reactive power were produced by power plants rather than have it compensated by the consumer?

Let's base the mental experiment on the amount of electrical energy consumed by the Finnish industry in 1997: 40179 GWh ^/1/. Let the average power factor (cos fi) without reactive power compensation be 0.90. The industry would need 19460 Gvar of reactive power.

According to the current tariff rate, a customer buying electricity avoids reactive power cost by improving his power factor into something between 0.987_IND and 0.999_CAP.

To facilitate computing, we can adopt a new term, apparent power, which is the geometrical sum of active power and reactive power to describe the actual power produced by power plants and consumed by industry.

We now assume that industry has improved the average power factor to the lower limit of the tariff, that is 0.987. This means that Finnish power plants have produced 40708 GVAh nominal power in a year. Without compensation, they would need to produce 44643 GVAh. The energy amount saved in this example, 3935 GVAh, equals more or less the annual apparent energy of one of the reactors of the Loviisa nuclear plant.

Thus reactive power compensation results in major savings in power demand. And the savings made on lower transmission cost are not included in the example.

COMPENSATION REDUCES EMISSIONS

The emission factor of carbon dioxide relative to electric production was 0.260 kg CO₂/GWh in Finland in 1997. With the total electricity production amounting to 73803 GWh, the CO₂ emissions totalled about 1.9*10¹³ tons.

If the amount of energy saved by compensation - 3935 GVAh - had been generated by power plants, the CO₂ emission would have amounted to 2.8 million tons if produced on natural gas, 3.0 million tons on peat, and 5.5 million tons on hard coal. ^/1/

Sources:

/1/ Energy in Finland - technology, economy and environmental impact, Helsinki, VTT Energy 1999.