Wind energy: our energy future lies in the sky

  • High wind turbines march across the USA landscape. Courtesy of Vestas Wind Systems A/S
  • Picture by Sean Woods
  • The latest turbine generation from Siemens has a six megawatt capacity with 75-metre blades, for a rotor diameter of 154 metres. The rotor has a swept area of 18 600 m2 – equivalent to almost two and a half soccer fields. Picture by Sean Woods
  • The latest turbine generation from Siemens has a six megawatt capacity with 75-metre blades, for a rotor diameter of 154 metres. The rotor has a swept area of 18 600 m2 – equivalent to almost two and a half soccer fields. Illustration by Siemens
  • Wind vanes point the turbine into the optimum position at Darling. Picture by Sean Woods
  • Turbines whirl away in a German rapeseed field; the country leads in total capacity, with 30 000 MW from 22 000 turbines.
  • Picture by Siemens
  • The UK’s London Array offshore wind power plant is situated over 245 km2 in the outer Thames Estuary off the Kent and Essex coast. Two offshore substations, right, bundle the power generated by 175 wind turbines before it is transported via high-voltage subsea cable to the coast. Picture by Siemens
Date:1 November 2012 Tags:, , ,

Fossil fuels aren’t the only game in town. Renewables – wind, in particular – are gaining traction as we plan for an electricity-hungry world.

South Africa is late in coming to the wind party. Given our substantial windswept areas – particularly in the south – that realisation is both puzzling and hard to swallow. Instead, we’ve gorged ourselves on a vast, readily available store of coal to become one of the world’s biggest emitters of carbon dioxide (CO2) and greenhouse gases.

Now we’ve gone into energy debt while we wait for new power stations to come on stream. And there is another pressing motivation: we need to look at cleaner, greener ways of producing electricity. Renewables, yes. Solar, perhaps. Wind, definitely.

Globally, wind is huge. Already, around 240 000 megawatts (240 gigawatts) of wind power is installed worldwide. That’s enough to power 40 million typical households in the developed world. The installation rate is doubling every three years, and wind is expected to be able to meet 9 per cent of the world’s electricity demands by 2020.

Our share of the total is, at 10 MW, a mere puff of wind in the gale. Can we make up for lost time?

The South African Government is looking to spend R100 billion in its Renewable Energy Independent Power Producer’s (REIPPP) Procurement Programme, the vast majority of which will be devoted to wind power. The scheme has attracted huge interest locally and internationally, says Energy Minister Dipuo Peters. In fact, as she commented recently, it has “propelled South Africa and its nascent renewable energy industry to the centre of this green revolution globally”.

That scheme forms part of the country’s Integrated Resource Plan, the roadmap to our energy future, which outlines the deployment of 17,8 GW of renewable capacity by 2030. To put that in perspective, our present total generating capacity is about 42 GW.

In addition to encouraging greener ways of producing electricity, the programme has wider goals. It is also intended to develop local industry and job creation.

The real cost of coal

Cheap South African coal has helped create a setup in which cheap electricity has been marketed to high-consumption industries. The country has focused on bulk generation of electricity, with centralised systems. However, the location of the coalfields in the north has involved a high-voltage transmission network required to distribute vast distances across country.

Problem is, until recently electricity tariffs were based on the costs of building existing power stations that had long been amortised. The picture changes drastically when you factor in the big new power generators being built (the R25-billion Medupi in Limpopo and R40-billion Kusile in Mpumalanga, which excludes interest that could quadruple the eventual total).

Eskom officials told Parliament’s portfolio committee on energy that electricity from Medupi could cost 97c per kWh, compared with winds 90 c per kWh. According to some, the levelised cost of electricity from Medupi – incorporating total project lifetime costs – are likely to be much higher than today’s tariffs: Eskom’s average selling price of electricity, is reported as being about 60c per kWh (“unit”). And that doesn’t take into account the societal costs such as air pollution.

It’s a wind world

The global wind industry is substantial, with a 2011 turnover of over R500 billion and employment of hundreds of thousands.

At the moment, Europe and China are the world leaders in wind power generation. The European Commission estimates that, by 2030, up to 135 GW could be installed in Europe’s coastal waters alone. That’s almost as much as the installed output of all the power plants in Germany, which totals 170 GW.

The European Wind Energy Association estimates that annual investment in wind power in the EU will double to 26 million euros by 2020. (Much of this money will be spent on replacing older units).

According to figures supplied by local wind project specialist and educator Francis Jackson of Windlab, the rate of wind energy installations shows a steady increase, with a total capacity of about 240 000 MW from about 6 100 just 15 years ago.

Germany leads in total capacity at nearly 30 000 MW from 22 000 turbines; 7,8 per cent of its electricity comes from wind. The state of Saxony-Anhalt gets half its electricity from wind alone. The German Association of Energy and Utilities recently reported that the country has set a new record during the first half of 2011 with 20,8 per cent of the country’s power production coming from renewable resources such as wind.

The world leader in cumulative capacity is China, at 26,2 per cent in 2011.

Denmark leads the world in the proportion of its electricity generated by wind power: 28 per cent of the annual demand of 35 TWh is generated by the country’s 5 000 turbines. Portugal (18 per cent), Spain (16,4 per cent) and Ireland (15,6 per cent) are also strong producers. Even a country as small as New Zealand has adopted an aggressive energy strategy this year that calls for 90 per cent of its electricity to be generated by renewable resources such as wind.

China has 46 000 turbines producing 62 000 MW. Its huge investment in wind came on the back of a government pushing wind energy growth as a key development area during the world economic crisis of the early 2000s.

Drivers that propelled the sector for the past five years are still at work. These include climate change, fuel prices, energy security and fossil fuel depletion.

In Africa itself, most development to date has been in the north, with 97 per cent of the continent’s total wind installations being Egypt (550 MW), Morocco (291 MW) and Tunisia (114 MW).

Regions to watch in Africa, says Jackson, are Ethiopia, Kenya, Tanzania and South Africa.

Exploiting potential

Anybody who lives in the Southwestern or Eastern Cape would suggest that there’s no shortage of wind. But is that an accurate assessment? And is the southeaster a viable source of long-term stable energy?

According to Jackson, availability of bankable wind data across the country is poor. Estimates of potential by various parties vary wildly: from 900 to 70 000 MW nationally. It’s hardly surprising that the REIPPP programme has been heavily oversubscribed.

The launch of the country’s first verified Wind Atlas in March 2012 gave the programme much-needed impetus. However, for various reasons, a significant amount of data is unsuitable for resource assessment, and there are no publicly available wind atlases of useful resolution. Private developers are doing their own monitoring using wind-mapping software.

Locally, Eskom installed a test project at Klipheuwel in the Western Cape’s Swartland in August 2002. In 2008, a four-unit 5,2 MW demonstration wind farm was installed at Darling, a short distance further north thanks to collaboration between government and the private sector under the facilitation of the South African Wind Energy Programme (SAWEP.) Cape Town buys power from the Darling operation and on-sells it via Green Energy certificates. A further single unit was installed in the Coega IDZ in the Eastern Cape in 2010.

Setbacks intrude

At the 2011 Durban UN climate summit, South Africa recommitted itself to the renewables path after an earlier attempt at integrating private energy producers with the national power network stalled. The new deal, focused on wind and solar, entailed an involved bidding system.

But in mid-September of this year, the process seemed to have staggered yet again. The government pushed back the bidding deadline on third-round projects, citing a need for officialdom to play catchup. That came as a massive blow to stakeholders, already impatient at the delay in finalising Rounds 1 and 2: they were meant to reach financial closure and be offered power-purchase agreements (PPAs) with the nominated power purchaser, Eskom, by June 2012.

Now, bidding will close in May 2013.

Through two successful bidding windows, a total of 2 460 MW has been allocated to 48 preferred bidders. Biggest of the preferred projects so far are a 135-MW facility at Cookhouse in the Eastern Cape, and one at Jeffreys Bay of nearly 134 MW. For the third window, this leaves 1 165 MW available. But, the Minister says, the process has made it clear that more will need to be made available.

Still, without the PPAs, the preferred projects are stalled. This could prove catastrophic for the smaller developers involved – and it may even persuade the bigger players to focus their energies in other, better-organised regions.

Sources: 1. Siemens: Pictures of the Future, Spring 2012. 2. Francis Jackson, lecture notes

 

Province

Active projects

Authorised

Authorised (MW)

Wind

Wind & PV

Wind

Wind & PV

Wind

Wind & PV

EC

16

1

23

1

3 843

90

KZN

2

MP

1

NC

24

7

2

1 732

2 288

WC

33

1

22

3 143

Total

76

2

52

3

8 718

2 378

 

Wind resources
Wind Action Group   www.wind-action-groups.com
SA Wind Energy Association, a trade and professional body representing the wind industry in South Africa  www.sawea.org.za
Yes to renewables  www.yestorenewables.co.za

Squeezing out more

The sight of turbines marching across the countryside is now typical in many countries. But it’s not a simple matter of putting a turbine in the path of the wind; placement is a huge challenge for the renewable energy industry. Power companies need to factor in wind turbulence and direction, and space, ecological and aesthetic considerations. All of these have potential to impact on the bottom line in a big way.

Where the wind blows is just one part of the equation. Capturing that energy efficiently is vitally important, too. The American Wind Association reports that if the United States can increase its wind energy capacity to 20 per cent by 2030, the country can reduce greenhouse gas emissions by 7 600 milliontons of CO2, reduce water consumption in the electric sector by about 50 trillion litres, and reduce consumer demand for natural gas by 12 per cent.

Wind turbine manufacturers are increasingly using sophisticated programming to optimise their setups. German company Siemens uses software to regulate wind force and output so that a rotor runs at below full speed, maximising its service life (the company quotes a design life of 20 years)

Optimal calibration of the rotor blades also lowers stress on the tower, so its walls can be made thinner, saving cost – some wind turbines stand 100 metres high. There’s also a system that can tell by the frequencies at which the nacelle vibrates whether the rotor blades are damaged.

Under development is software that regulates the load on each individual rotor in a wind farm to optimise overall performance. That’s because a turbine’s wake can cause signicant losses in nearby turbines. Cutting back on the power output of the front turbines reduces this effect on the turbines behind.

Current state-of-the- art turbines can have blades 50 metres and more long. The chief technology of cer at Siemens Wind Power, Henrik Stiesdal, predicts that land-based units will top out at around 4 MW. Offshore turbines could reach as much as 10 MW, with 100 metre-long rotor blades.

Danish energy company Vestas Wind Systems has announced that it will use IBM big data analytics software and an IBM “Firestorm” supercomputer to improve wind turbine placement for optimal energy output. The systems will analyse petabytes of data, from weather reports to tidal phases, geospatial and sensor data, satellite images, deforestation maps and weather modelling research, to pinpoint installation. The analysis, which used to take weeks, can now be done in less than an hour.

  • Why are we not utilizing the natural energy of wind turbine’s? Surely this would be the answer to our Eskom sharks? How many would one need to keep a basic three bedroom house running?