To assess the viability of a proposed decentralised wind energy system, it is essential to obtain knowledge both about the present and anticipated pattern of power and energy use, and also about the meteorological regime and other environmental and community aspects that may be specific to the area and need to be considered.

ASSESSING THE CONSUMER LOAD DEMAND

What data are needed?

Consumer demand can best be described on two timescales - long-term (up to 1 year) and short-term (less than 1 minute). Both can have a major impact on the design, viability and operation of decentralised wind-diesel systems.

The long-term data will show if the demand changes on a daily, weekly or seasonal basis. This is most important as it is vital to match the available wind energy to the consumer demand requirements. A simple comparison of annual totals will fail to identify this. Often it may be possible to delay particular consumer demands (for example heating and refrigeration loads) by a few hours to obtain a better match between supply and demand. Sometimes there may be a correlation between available wind energy and electricity use. This is particularly true where there is a high heating component to the demand. Long-term data are also important when deciding on the relative ratings of the components of the wind-diesel system. Ideally, the information described in Table 2.1 should be obtained when assessing a site.