Wind power is one of the fastest growing renewable technologies.
Energy efficiency is often neglected in times of low oil and gas prices. But since the turn of the century the rising cost of hydrocarbons has driven energy-poor countries to look at developing diversified and independent energy supplies.
As a result, there is growing interest in exploiting renewable sources of energy, in particular wind and solar power.
According to the Global Wind Energy Council (GWEC), more than 20 GW of wind power was installed across the world in 2007, led by the US, China and Spain, bringing the total installed wind energy capacity to 94.1 GW.
Last year, the global wind market was worth some US $36 billion in new generating equipment.
“The growth rates we are experiencing in wind energy continue to exceed our most optimistic expectations,” says GWEC secretary-general Steve Sawyer.
“Globally, wind energy has become a mainstream energy source and an important player in the world’s energy markets. It now contributes to the energy mix in more than 70 countries.
League leaders
Germany leads the world in the use of wind power, with 22.3 GW installed or 23.6% of the world’s total wind power capacity. The US and Spain follow on 16.8 GW and 15.1 GW respectively.
Wind energy still only accounts for around 1% of global electricity generation, but this figure is expect to rise in the years ahead.
“Emissions-free wind power can be brought online quickly, and must play a major role in meeting climate protection targets,” adds Sawyer.
This is especially the case in the critical period between now and 2020 when greenhouse gas emissions must peak and begin to decline if we are to avoid the worst impacts of climate change.”
The GWEC estimates that Europe’s wind power capacity of 57.1 GW saves around 90 million tonnes of carbon dioxide each year, producing 119 TWh of electricity in an average wind year.
It predicts that by the end of this decade the cumulative capacity of all wind installations will reach 149.5 GW.
Suitable sites
Of course, not all locations around the world are suitable for wind power. A minimum wind speed of 5 m per second is needed for harnessing the energy to become worthwhile.
To generate sufficient power, a large number of wind turbines are needed: statistics says a 1 000 MW wind farm would occupy an area of 50-150 km2.
Wind turbines capture energy from the wind using their blades, which turn. When there is no wind the blades remain at a 45-degree angle so that the turbine can draw maximum energy from gentle winds.
Turbines begin to produce energy when wind speeds reach about 4 m per second. The blade gradually rotates towards an angle of zero degrees with the broad surface facing the wind.
When the wind strikes the blade, it creates positive pressure on the front of it and negative pressure behind it.
In other words, the wind pushes against the front edge and creates a suction effect behind the blade, which makes the rotor turn. At maximum rotational speed, the blade tips reach a speed of 250 km per hour.
Offshore option
Wind turbines can be built on land or out at sea. According to UK energy consultants, Douglas Westwood, there was a total of 919 MW of installed offshore wind power capacity at the end of 2006, comprising 436 turbines.
The world leader with 46% of the total capacity installed or 426 MW was Denmark, followed by the UK with 309 MW and the Netherlands on 127 MW
Douglas Westwood forecasts the global offshore wind capacity will rise to 3.6 GW by the end of this decade, with annual installations reaching 1.2 GW by 2011. It expects the average project sizes to be greater than 200 MW.
The UK is identified as the best market for offshore wind energy in the world due to its climate. At the end of last year, the British government announced a huge expansion of offshore wind capacity with plans to build around 7 000 turbines.
Offshore wind turbines are based on the same technology as their onshore counterparts but the main difference is their size.
A typical onshore turbine today has a height of between 100-120 m and blades 30-40 m long. Most offshore wind turbines are at the top end of this scale.
The physical constraints of transporting large components such as blades do not apply to the same degree offshore, and the costs of installation offshore is much the same regardless of the size of turbines. It is therefore more cost-effective to use large machines with higher energy yields out at sea.
The cost question
According to Douglas Westwood, the cost of installing new capacity and producing wind offshore over the next four years will be some 42% higher than in the period 2002-2006, rising to US $3.25 per MW from US $2.29 per MW.
The main expense of wind power is the turbine itself and demand for turbines is currently outstripping supply. Furthermore, only a handful of manufacturers supply the offshore market.
There are also very few specialist contractors who can install the turbines at sea and general contracting and engineering bottlenecks around the world are impacting project deadlines, as well serving to push up costs.
Nevertheless, wind energy still compares extremely favourably with solar power technologies. Consultancy firm, McKinsey & Company estimates that offshore wind power costs €140 per MWh (US $220 per MWh) compared to €350 per MWh for solar power using photovoltaic cells and €200 per MWh for concentrated solar power.
Regional potential
Clearly, where wind is available, it makes sense financially to explore the potential for generating power.
In the Middle East and north Africa (MENA) region, Egypt, Iran, Morocco, and Tunisia already have wind farms in operation.
These countries also offer the best prospects for further deployment of wind power. The GWEC expects 900 MW of new capacity will be added over the next three years in the MENA region.
Egypt enjoys an excellent wind regime, particularly in the Suez Gulf, where average wind speeds reach more than 10 m per second.
Estimates say the area could host 20 GW of wind farms. The Egyptian government aims to satisfy 20% of the country’s power needs using renewables by 2020. Around 850 MW of wind energy is scheduled to be installed by the end of 2010.
The Moroccan government has approved wind farms with a total capacity of 1 000 MW to come onstream by 2012. And estimates say 30 GW of power could be captured using wind farms in Iran.
Elsewhere, in the region, experts say there is huge potential for harnessing wind power off the Omani coast and winds of 11 m per second have been recorded in Fujeirah, in the UAE.
Given the intense solar radiation in the region, solar power remains the obvious first choice for renewable energy in the Middle East. But wind power with its significant cost advantage should not be overlooked as an option where nature allows it.
