Wind Power

Many, particularly in the media and the green movement, suggest that windmills will save the world from the greenhouse effect.

In the twenty years since I wrote the original paper wind technology has come a long way. Wind turbines are very much larger and more efficient. Larger turbines are higher and have a much greater swept area capturing much more wind. A typical 2MW turbine well located in a good wind province now pays back its whole of life construction, maintenance and removal energy debt in around six months instead of three years.

But wind is limited in the contribution it can make.  Wind generates electricity for about a third of the life of a well placed wind turbine; due to the intrinsic variability of wind energy and the fluctuating nature of electricity demand.

Even in windy Denmark: attached to the larger European grid; with a big investment in wind; as well as small cogeneration units (to standby against windless, or overly windy, conditions), wind has trouble supplying more than 20% of total electrical energy.

To match power generated to demand, excess wind turbines have to be turned off during periods of good wind but low consumer demand. A turbine that operates for only half the time takes a year or more to repay its sunken energy and one that is seldom or never used never repays that energy. Thus adding more turbines, once the power generated during optimum wind conditions regularly exceeds minimum consumer demand, is counterproductive. 

In other words once this 20% limit is reached every new increment of wind requires four matching new increments of base-load and fill-in energy.

In many places, like much of Australia, good wind provinces are rare or very distant from the main centres of electricity demand. To minimise losses generation should be adjacent to the consumer.  In Australia, and particularly in Queensland, grid losses already consume nearly a third of the energy on its way to the consumer, even longer distances to distant wind provinces could mean that half or more of the power produced is lost during transportation. 

Wind can and does contribute to the energy mix but as can be seen above it is not a replacement for coal and oil. Once the local practical maximum is reached,  each additional increment wind generation requires other (base-load and peak-load combined) generation to expand around four time that amount. At the present time only gas or nuclear power is a practical replacement for base-load coal in Australia but oil and gas can provide peak-load supplementation.

To read a more in-depth discussion of renewable electricity technologies  Follow this link...