The Renewable Energies hall was one of the most popular at this year's six day Hannover Messe, the largest industry trade fair in the world. The nearly 50 wind industry stands were impressively professional. The most controversial debate taking place front stage at the congress was over the potential of clean forms of energy, but other telling debates took place in the wings, such as how to compensate for the intermittent supply from renewables and whether megawatt scale turbines are sensible. These three areas of debate are reported in some detail.

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Rumour had it that "Renewable Energies Number 14" was by far the best visited hall during the whole of the six day Hannover Messe. The industry trade fair, the largest in the world, was held April 3-8. Whether the rumour was true or not, Hall 14 was certainly an exciting place to be. To start with, Chancellor Helmut Kohl put in an appearance on the morning of the opening day; then there were the 100 or so exhibition stands spread over 4000 square metres, overrun with visitors from far and wide throughout the week. Many company reps on the impressively professional wind stands must have lost weight during the week as they nearly all reported there was never time for lunch.

Wind exhibitors were largely the industry's well-known names from Germany, Denmark and Holland. As well as some 35 or so wind turbine manufacturers, there were also more than a dozen component suppliers. Most wind companies were from mainland Europe, but turbine manufacturers FloWind, from the US, Markham, from the UK and Mitsubishi, from Japan, were among those who made the journey from farther afield. Interestingly, Germany's largest utility, RWE Energie, chose to exhibit only in the fair's renewables hall, displaying its hydro, solar and wind activities.

Potential wind turbine customers from home and abroad (particularly India) crossed paths in Hall 14 with many curious fair visitors who popped in to have a look at the renewables newcomers, even though their main interest was in other industry sectors. Wind exhibitors also had the opportunity to rub shoulders with representatives of other renewables technologies with whom they will probably sooner or later be co-operating. And at the end of the day, those wishing to recuperate their strength could take a rest on mattresses and have their brains rinsed at the Brainlight Mental Systems stand, ready for the next day's effort .

The renewable energies exhibition was organised by Winkra-Recom, which in the past has staged the Husum wind event, now under new organisation. Complementing the exhibition, Winkra also held a five day renewables congress. This covered wind, solar and biomass and attracted around 1000 participants.

Smoothing the way for renewables

Although the most controversial debate taking place front stage at the congress was over the potential of clean forms of energy, other telling debates were taking place in the wings: information has begun to filter through on ways of compensating for the intermittent supply from renewables such as wind and solar; and wind turbine manufacturers and their potential operators had much to say on the pros and cons of moving into megawatt scale machines.

On the future of renewables, the first discouraging statements came from Heinrich Kolb, under secretary at Germany's Federal Economy Ministry. Drawing on reports on renewables, produced by expert working groups for the country's major energy policy debate in 1993, Kolb said that within ten years the contribution of renewables to Germany's electricity production could increase to only 6% compared with 5% at the moment. This would involve an 11-17% increase in hydro production, a rise in wind generation by a factor of between four and ten and photovoltaic increasing its contribution by eight to 15 times. "This increase does not correspond with society's views and hopes for renewables," he remarked. His frugal forecast was countered energetically by Hermann Scheer, Federal MP and president of solar association Eurosolar. "From basic principles, renewables are inexhaustible so how can you limit them to such low percentages?" he asked. Eurosolar has shown, in a study for the European Commission, that renewables could supply 50% of Europe's energy by 2020 and at the same time create 1.25 million jobs, 250,000 in wind alone. He anticipates: "In just a few years wind energy will be the cheapest method of electricity generation in the world -- by a long chalk."

It appears, however, that Scheer lives on a different planet to the one occupied by Hans-Dieter Harig, chairman of giant utility Preussenelektra, so diverse were their views. Harig said fear of running out of fossil fuels is not enough for a massive expansion of renewables today. He quoted a study by Munich university on the costs of reducing CO2, the additional specific costs of which, when using wind to replace coal, would be DEM 150 for each tonne of CO2 saved. With nuclear the extra costs would be zero, he added. Harig nevertheless agrees that solar power should be used. Surprisingly, he remarked that an appeal for using solar combined with nuclear could bring positive results. He concluded, however, that "Preussenelektra has tried out all available renewables and they aren't any help. We know the perspectives better than those who just write reports." Later he warned: "There is no point in dreaming of worlds which aren't there."

Harig's mood visibly darkened as he listened to Uwe Carstensen, president of the German renewables association, BEE. In particular, Carstensen criticised the attack by utilities on the Electricity Feed Law, which forms the foundations of the wind market (Windpower Monthly, April 1995). Harig claimed he had no knowledge of the extremely controversial utility stance where wind turbine operators have been told that power payments under the law are only being made provisionally.

Carstensen also took those to task who claim wind energy is not competitive. He pointed out that no new generator can compete with the low generation costs achieved by power stations which have long since written off their loans. But if wind turbines were financed over ten to 15 years, they, too, would be able to compete on equal terms with conventional power stations. If the playing field were levelled now and utilities were forced to tender for the least cost and most environmentally-friendly power generation technology when building replacement capacity, then wind could easily play an important role, he said.

Looking at a new mi

xNew opportunities for taking far larger blocks of renewables capacity onto the grid are now being discussed. Perhaps surprisingly, Harig commented that there would be no problem in taking 1000 MW or more of wind energy on to the grid, for example in Schleswig-Holstein. "We do this anyway when 1000 MW capacity is closed down for any reason," he pointed out, backing arguments put forward by wind lobbyists, but which have been refuted by utilities for years.

Carstensen pointed out that wind and hydro complement each other well. The wind often blows strongest during times of the year when water levels are low. In a 24 hour cycle, wind power could be used at night for hydro pumped storage, which can then be used for peak load demand during the day.

On a similar theme, wind firm Enercon has begun a programme of turbine monitoring with utility EWE to examine problems of load management. One aspect is how to make turbines shut down more slowly in storms to give time for conventional power stations to increase their output correspondingly. Enercon is also looking at means of decentralised energy storage such as batteries or flywheels (capable of 90,000 rotations per minute and supplying 100 kW) so that wind systems can provide constant power for periods of two to three hours even when there is no wind. Other electricity storage systems, using compressed air and super conductive magnetic coils, are already utilised in isolated cases by the traditional power industry.

Wind energy systems have a capacity factor of 20-40% said Winkra Rekom. When combined with renewables where output can be fully regulated, such as hydro power or biomass, normal load management systems operated by the electricity industry today could easily cope with a much higher share of wind. In Denmark, the Elsam utility group is currently groaning because wind makes up 5.8% of its generation. But there will come a time, says Aloys Wobben of Enercon, when it will be possible to load manage systems consisting of up to 70% wind and 30% gas.

Big versus small

The advantages and disadvantages of megawatt scale turbines provoked much discussion. The general feeling from Danish manufacturers was that the move towards ever bigger sizes is typical only of the German market and is driven by the demands of German customers. There is no other country where potential customers are so bothered about size, though the concern can be partially attributed to the desire to get the most out of the limited number of good sites. One manufacturer admitted: "We aren't at all keen to move into the megawatt class already, but we have no choice. This is what German customers want."

Many have doubts about the sense of doubling turbine size and taking on a whole new gamut of problems only 18 months after 500 kW and 600 kW turbines came on the market -- and at a time when they are still throwing blades. Heinz Klinger from the Schleswig Holstein investment bank, Wing, says: " We are trying to apply the brakes."

Opinions were varied as to where the megawatt-plus machines will be installed. Some thought only in Europe, and mainly offshore. Others thought ways would be found to overcome logistic problems in developing countries to get the jumbos up in less industrialised parts of the world. For example, both Enercon and Seewind in Germany are considering ways of hoisting their 1.5 MW and 750 kW machines, respectively, without huge cranes. Another view was that the large turbines would first be concentrated in a few areas, such as industrialised southern India. Production of these machines would later spread through the subcontinent to Indonesia and beyond.

At least some manufacturers are privately plagued by niggling doubts over jumbo turbines. Although outwardly confident that their costs per kWh will certainly match, if not undercut, the middle sized turbines, there is still a lot of uncertainty. As one worriedly asked, what if the 1.5 MW class doesn't sell, but the 600-800 kW does and we haven't got one to offer? The large turbines are heading for 60 metre towers and more. What if the planning authorities decide they don't like them and refuse to grant licences? "Why don't manufacturers aim at real mass production of their 500-600 kW class?" was the probing question of another industry observer. One million 500 kW turbines is real series production, but the equivalent in 1 MW machines -- some 300,000-500,000 -- is not, he said.

The aim seems to be to get costs down to DEM 1500 or DEM 1000 per kilowatt installed -- and this will require real mass production. German manufacturers aiming to sell their 1.5 MW machines for around DEM 2.5 million would appear to be approaching DEM 1500 per kW, and are confident their jumbos will compete with the middle class of machines. But while it is interesting to speculate, only time will show what the real costs are and what the market will take.

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