22. Wind resources are highly site-specific. Island countries and countries withcoastal and mountainous areas possess good wind resources. hlind may be used todrive electric aenerators or mechanical pohrer devices. In rural areas indeveloping countries, snall multibladed windrnills employing horizontal axes - ofless than l0 kilowatts (khl) - are stilt in use for punping water. At the sametime, new multibladed and sailmill desiqns made from woocl and sailcloth have beendeveloped for water pumping, and wind systens in the range of l0 to 11000 k!{, withdiesel back-up or some form of electrical storage, are already an acceptablealternative to the conventional diesel-powered generators. For example, a 40-kWdesign is being tested in China in an island setting, and a 550-kt{ system has beenplanned for installation in Malta. Research and development work has also beendone on "low-solidity" systems, in which the ratio of area of blade to area sweptby the plade is relatively low. Such devices use a propeller-like blade on ahorizontal axis or an egg-beater-shaped complex of blades on a vertical axis. Systems of 10-kW power can probably be relied on for water pumping, heatinq anddesalination before the end of the century. Beyond the turn of the century,large-scale wind-generated electric pohrer will probably be used to supplyeleetricity grids, a possibility where the wind "y=t"r" employed are of thelow-soridity t-vpe operating at capacities of over 1,000 kw. (h) Ocean energy 23- The availability of ocean energy is, Iike wind energy, high site-specific.This energy alternative is an attraetive one, particularly for island developingcountries, as fresh water could also be provide<t as a uy-product. oceanthermal-energy conversion systens in the range of 11000 to 10,000 kt,tl nay becomecommerd'ially viable before the end of the century. Beyond that, research anddevelopment carried out on ocean energy systems utilizing, for example, urave,current, salinity gradient and advanced photoconversion processes may rnake suchalternatives teehnically and economically feasible (E/L985/7g, paras. 35-37).A/40/sl-r English Page 10 B. Probable energy picture by the year 2000 24. Two previous studies (E/IgL3/gL and Corr .L, A/3g/420 and Corr.I), which contain projections of the denand and supply of energy through the year 2000 and of the accompanying financial gap, provide a long-term view of energy use in the developing countries. A brief summary is presented here. Total commercial energy consumption has been projected to increase from 15.8 mbdoe in 1980 to 53.0 nbdoe in the year 2000, at an average annual rate of 5.9 per cent.24/ In the composition of energy use, by source, it is expected that there will be interfuel substitutions in favour of non-oil sources, particularly coal. Nevertheless, it should be noted
**Analysis**
The text discusses the potential of wind and ocean energy as alternative sources of power, with a focus on developing countries and their energy consumption patterns. It also provides projections of energy demand and supply by the year 2000. This suggests that the text is related to the development of sustainable energy sources and their impact on the economy.

**Category**
Natural resources and environment, Economic development