J – Germany, a Case Study


Germany commenced wind power implementations in 1987, long after the US and Denmark, and between 1997 and 2007 was briefly the world leader in installed wind capacity and electricity production. In 2008, the US passed Germany in wind electricity production and is poised to pass Germany in installed capacity.

For the first 10 years growth was moderate, and small-scale, but accelerated rapidly after the SPD-Green federal government coalition was formed in 1998. At that time, Germany announced the phase out of all nuclear plants (23,000 megawatts, or MW) by 2021 and the implementation of a major alternative energy program, largely based on wind power.

By 2007, Germany had over 22,000 MW of wind power installed, which represents about 16 per cent of total capacity. This is one measure of wind penetration into the electricity system. Another is the amount of wind production as a percent of the total production, which will be substantially less.

Analysis of wind power developments in Germany reveals a number of important considerations and provides a very instructive case study. For example, it is becoming clear that the amount of wind electricity production as a per cent of the total is a key indicator of the limit for wind, and 5 per cent, as in Germany, is at the high end of the range. This is the reason why the US will take the lead globally. Its current penetration in electricity production is only about 1 per cent.

Also, the realities of wind’s capacity factor, capacity credit, and the questionable effect of wind power on CO2 emissions reductions become evident through understanding events in Germany.

Capacity Factor or Production Factor

Capacity factor is the percentage of a generation plant’s capacity that produces electricity over some period of time. It is typically calculated for a year by taking the amount of electricity actually produced in megawatt-hours (MWh) divided by the “name plate” capacity (MW) multiplied by the total number of hours in a year.

For most generation means, the amount of electricity produced is 50-90 per cent (plus) of total capacity, depending upon how much of the capacity is called up by the system operator. Nuclear, which is not easily varied, is at the high end, supplying base power. Hydro and coal can be used for base supply, but can also be used in an intermediate role where they would be called upon as daily demand increases. Gas turbine is typically called on less often depending upon which of two basic types is available. Combined Cycle gas turbine (CCGT) is typically used in an intermediate role, and Simple Cycle Gas Turbine (SCGT, sometimes called Open Cycle Gas Turbine OCGT) is used primarily for peaking power. The range for gas turbine use is from 10 per cent or less to 50 percent or more.

In the case of wind plants, the capacity factor is not determined by how often the system operator calls on them but on the limited and unreliable availability of the fuel, wind. In extensive, mature installations the capacity factor is typically about 20 per cent. It is not unusual in new, less extensive implementations of wind plants for capacity factors to be in the high 20’s before a number of factors start to come into play, for example, wear and tear, turbine blade contamination and the growing practice of curtailment of wind production (shutting down wind turbines) during periods of high output. In Germany’s case it is 17-18 per cent.

As a result, Germany’s 22,000 MW of wind, with a capital cost of about $40 billion, is really effectively a capacity of only about 4,000 MW in terms of production capability. As a result, the wind plants in Germany represent 16 per cent of the total capacity (MW), but only about 5 percent of the electricity production (MWh).

Capacity Credit

This is a measure of how much other capacity a generation means can displace. For most types of generation plant this is 100 per cent. Because of wind’s fluctuations, unreliability and low production capability, as described above, it has a capacity credit of only 8 per cent of total wind plant capacity in extensive installations like Germany. In this case wind plants displace less than 2,000 MW of other generation capacity. Capacity credit decreases as the penetration of wind increases as a percentage of the total electricity system capacity. This is acknowledged by E.ON Netz (which has a large percentage of the total wind plants in Germany in its area of operations), deENet (a consortium of 90 research organizations and services providers in Germany) and the European Wind Energy Association.

Table 1 shows the results that increasing wind capacity will have on the German electricity system assuming a 2% annual growth in total capacity and electricity production. The starting point for the data is from Eurelectric, which is an association representing the European electricity industry, and the projections for wind capacity and capacity factors are based on the German Energy Agency (DENA) report on the integration of wind energy. The increasingly higher capacity factors are the result of significant amounts of offshore wind implementations.

Table 1 – Effect of Increasing Wind Capacity in Germany





Installed Wind Capacity

20,600 MW

22,000 MW

36,000 MW

48,000 MW

% of Installed Capacity





Capacity Factor





% of Electricity Production





Capacity Credit





Other Capacity Displaced

1,700 MW

1,700 MW

2,000 MW

2,000 MW

Capital Costs

$40 billion

$43 billion

$90 billion

$140 billion

Note that in 2015 Germany will have reached the same penetration in capacity terms as Denmark, and will have to find ways to dump wind output when it is in high production mode, which is especially true with any strong wind regime, for example, offshore. Denmark has to do this to reduce the wind share of actual production to a level of about 6 per cent or less. Unlike Denmark’s situation, there will likely be few neighbours that will be in a position to take this excess production from Germany, even if there was an effective way of delivering it. Germany would likely have to simply curtail wind production. The added investment of $47 billion by 2015 is wasted. There is no sense in this program, past and future.

According to Dieter Helm, Professor of Energy Policy, University of Oxford, and an economist who specializes in utilities, infrastructure, regulation and the environment, concentrating on the energy, water and transport sectors in Britain and Europe, there are already concerns in Germany that as wind capacity moves towards 20 per cent of installed capacity (line 2 of Table 1), grid stability may be endangered.

Figure 1 shows the effect of the presence of wind in the total generation mix. The basis for the information is the same as that for Table 1.

Figure 1 – The Redundancy of Wind in the Generation Mix


In 2007, Figure 1 shows that for a demand of 95 GW (gigawatts or 1,000 MW), 119 MW of capacity is required. This is the capacity required without wind in the generation mix. The difference is the normal reserve margins that are required to provide a reliable electricity system, protecting against major plant failures and extreme weather conditions. With 22,000 MW of wind only 1,700 MW of other capacity can be displaced. This means that about 139,000 MW of total capacity is installed, or 20,000 MW (of wind capacity) more than is needed to meet electricity demand. The retained conventional capacity is required for wind backup to ensure electricity demand is reliably met. The excess wind capacity increases to 34,000 MW in 2015 and 46,000 MW in 2020.

If wind production was steady at its annual production average, it would make some contribution to the reduction in fossil fuel use and CO2 emissions reduction, albeit small. Because wind fluctuates randomly, frequently and sometimes over a wide range, the shadowing backup is required to frequently ramp up and down in opposition to wind’s fluctuations. Remember that doubling, or halving, wind speed produces 8 times the resulting fluctuations in wind electricity output (changes by a factor of three in wind speed, are magnified by 27 times). In this mode the shadowing backup generators (typically gas, and possibly some coal in Germany) consume more fuel and produce significantly higher CO2 emissions than normal, steadier operation. This is accentuated when wind is in its highest production period.

This illustrates the basis for shadowing backup in the 90-95 per cent range, as E.ON Netz reports, for implementations at the same wind penetration as Germany.

Will Germany continue with its very questionable wind power policy? I predict that they will de-commit with the rationale that as there is a shortage of wind turbines world-wide, and as they have already done their part, so to speak, they will allow their manufacturing capacities to be re-directed totally to international markets, or for movement to other countries. The latter move would undoubtedly be dependent upon the countries accepting new plants providing significant financial support. Further, they will turn their attention to the development and use of solar power, a course they have already embarked on. This provides a very plausible exit strategy from wind.

German CO2 Emissions Reductions

The German wind policies have not produced any noticeable positive effects, especially in consideration of the investment involved. Although Germany has reduced CO2 emissions approaching 20 per cent below 1990 levels (Germany’s Kyoto target is 21 per cent), this has been accomplished largely by closing the worst polluters in East Germany after reunification in the early 90s, yielding about 15 per cent. According to the European Environment Agency, any gains since are mainly due to some shift from coal to gas in the production of electricity and heat, and reductions in emissions from road transportation, households and services. Claims of reductions achieved by wind are theoretical calculations based on wind power production, ignoring the effect of the necessary shadowing backup generation operation.

It is noteworthy that the DENA wind integration study, which covers the period to 2020, did not project CO2 emissions beyond 2015.

Recently Germany has raised the issue that they should receive allowances for the increased CO2 emissions (about 100 million tons per year) if they remove the nuclear plants. This is because they would be replaced largely by coal (or gas) generation, and Germany plans to implement 25,000 MW of new coal plants over the next few years. The idea that wind power has a role in nuclear plant displacement is difficult to maintain.

As with the wind power policy, if the German Chancellor Merkel’s CDU party wins enough seats in the 2009 national elections, it could join forces with Germany’s Free Democratic Party (FDP), escape the coalition with the SPD, which set the present energy policies in place, and abandon the plan to phase out nuclear plants.

Geographic Dispersion of Wind Plants

This does theoretically provide the prospect of some smoothing among wind plants spread over large areas, but in practice, the effect could be small.

A recent study performed by Oswald Consultancy Ltd in the UK established the relatively high correspondence of weather conditions in much of the UK and northern Europe, which offsets much of the opportunity to take advantage of wind plant dispersion over large areas. Further considerations include the ability of neighbouring countries to accept any significant amount of another’s excess wind production, and the availability of the interconnection means to allow this. Oswald concluded that it would be difficult to justify such interconnections between the UK and its neighbours.

Energy Probe in Ontario reports that hourly correlation between the existing wind plants in Ontario is 60-70 per cent for those in Southern Ontario and 30-50 per cent between these and the Prince Farm wind plant near Sault Ste Marie. Further, it should not be assumed that the electricity grid in Ontario is structured in a way that would facilitate the levelling among wide-spread wind plants.

Final Comments

The main lesson than can be drawn from Germany’s experience was previously learned in Denmark. It is that wind electricity production at about 5 per cent of the total is the top end of the range that can be managed in a country’s, state’s or province’s electricity system. Problems for the electricity system become evident below that even at a few per cent. A recent major electricity system outage in Europe was the result of wind plant operation, primarily in Germany.

Ontario’s wind penetration in electricity production terms is 1 per cent now and will be 5 per cent in 2015.

Last updated June 28,2009 (involving the relationship description between wind speed changes and electricity output of wind turbines)

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1 Comment »

  1. W.E. Goodrich said

    This is one of the clearest and most succinct summaries of the German situation I have read. Congratulations on a fine job!

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