Wind Energy Technology And Potential
Economist ran a report on technology and featured Wind power. The main points are:
- The potential is huge and price is cheap
- Technology has improved hugely over the years
- Scale matters. Larger turbines are better
- Challenge is how to transport the produced energy frm wind to consumers
Wind power is attractive because it is a widely available and renewable source of energy that produces neither pollution nor climate-changing greenhouse gases. Once the turbines have been installed, the only “fuel” they need is the wind. And global wind resources are so vast that they could easily meet the world’s current energy needs, at least in theory. Wind generates only about 1% of all electricity globally, it provides a respectable portion in several European countries. According to a study by researchers at Stanford University, global wind-energy potential in 2000 was about 72,000GW—nearly five times the world’s total energy demand.
About the technology:
When sunlight heats the Earth, it also heats the atmosphere. As hot air rises, cooler, heavier air rushes in to fill its place—thus creating wind. For more than 2,000 years people have captured this energy with windmills and used it to do useful things, such as grind grain or pump water. By the late 19th century, windmills were also being used to produce electricity, mostly in rural areas.
Compared with traditional windmills, however, modern wind turbines are far more efficient. Their rotors are pointed into the wind under computer control, and their blades exploit the phenomenon of aerodynamic “lift” that keeps aeroplanes in the air. Turbine blades are shaped like aerofoils, with one side curved and the other almost flat. This shape causes the air to flow more quickly over the curved side than the flat side, and the fast-moving air results in an area of low pressure on the curved side of the blade, which causes the blade to move and the rotor to turn. The blades are attached to a rotor hub, which is in turn connected to a drive shaft. But this shaft spins quite slowly, so a gearbox is used to get the drive shaft to turn a second shaft at a much higher speed, suitable for spinning a generator to produce electricity. In a wind farm, the electricity from multiple turbines is collected and fed into the grid.
Excerpts from the Economist.com:
The technology needed to tap into this source of energy is getting cheaper: the cost of generating electricity from wind power has fallen from as much as 30 cents per kilowatt hour in the early 1980s to around ten cents in 2007. Various incentives, in the form of tax credits and feed-in tariffs, mean that wind power is already cost-competitive with electricity derived from natural gas and even coal in many markets. With a tax of $30 per tonne of carbon dioxide, says Maria Sicilia of the International Energy Agency (IEA), electricity produced from wind could compete with fossil fuels in most markets even without subsidies.
Despite some difficulties in transporting, deploying and maintaining large turbines, the industry still believes that bigger is better. Onshore machines are creeping up to about 3MW in capacity, and some offshore turbines on the drawing board are more than twice as powerful.
The greatest obstacle to the wider adoption of wind power is the need to overhaul the power grid to accommodate it. Transmitting wind power from rural areas with strong winds to populated areas with high demand will require expensive new transmission lines. In addition, the power grid must become more flexible, though some progress has already been made. “Although wind is variable, it is also very predictable,” explains Andrew Garrad, the boss of Garrad Hassan, a consultancy in Bristol, England. Wind availability can now be forecast over a 24-hour period with a reasonable degree of accuracy, making it possible to schedule wind power, much like conventional power sources.
