Does wind power grow faster in Germany or the UK?
Comparing wind power in Germany and Japan is relatively easy: in 2016 Germany generated 14 times more of it in absolute terms (77 TWh vs 5.2 TWh) and 26 times more in relative terms (13% vs. 0.5% of each country's electricity supply) than Japan. Such striking difference requires a convincing explanation, for example worse geographic conditions in Japan. But what if the situation is less obvious, for example if Germany is compared not to Japan, but to the UK? In 2016, Germany produced about twice as much wind power as the UK (37 TWh). However, since Germany's electricity system is larger, the relative difference between the two countries is small: 13.1% in Germany vs 10.6% of electricity in the UK was generated by wind. To complicate things further, not so long ago, the difference between Germany and the UK was almost as big as the difference between Germany and Japan today: for example in 2003, Germany generated about 15 times more wind electricity in absolute terms and about 10 times more in relative terms. Does it mean that Germany was more committed to wind power in the past, but that the UK is rapidly catching up? Or are we simply observing a predictable trend of some sort that has little to do with national policy differences?
To answer this question let us look at the evolution of the share of wind power in the national electricity supply of the two countries over time, as shown by the dotted lines in the figure below. To disentangle the change in wind power from the changing electricity supply we will analyse the ratio of the current wind power generation to the electricity supply in a reference year 2005 (solid lines on the figure). We will thus correct for different sizes of electricity systems while taking the irrelevant demand dynamics out of the equation. Specifically, this will adjust for the fact that the electricity demand (and supply) in the UK has been dropping much faster than in Germany.
Dotted lines show share in the current year's supply, solid lines - the ratio of wind power produced in a given year to the electricity supply in 2005. Data by IEA (2017) processed by V.Vinichenko.
The figure above shows that over the last two-and-a-half decades the share of wind power in both countries has been steadily growing, that Germany has always been ahead of the UK, and that the gap between the two countries was first expanding and then narrowing.
To make sense of this pattern we need insights from the technology diffusion theory. The uptake of a new technology, such as wind power, follows the so-called S-curve, a pattern discovered by sociologist Gabriel Tarde over 100 years ago. Tarde observed that the spread of social novelties is initially slow (the formative phase), then expands exponentially, and finally slows down and plateaus. During the exponential phase, the growth of a new technology is proportional to its existing use. In other words, countries that have more wind power would also expand it more rapidly. For example, between 2005 and 2006 the generation of wind power in the UK grew by 1.1 TWh/year: from 4.2 TWh/year to 5.3 TWh/year, i.e. by ca 25%. In the same period the generation of wind power in Germany grew by 9 TWh/year from 31 TWh/year to 40 TWh/year i.e. by ca 29%. Though Germany added almost 8 times more wind power, the growth in both countries was roughly proportional to their existing generation.
Does this pattern holds across more years? In 1994, wind power generation in Germany was 0.23% of the 2005 electricity supply, three years later (1997) it exceeded 0.5%, and seven years later (2001) it was ≈1.7%. In the UK, wind power produced 0.25% of (the 2005) supply in 2001, 0.5% - three years later (2004); and ≈1.7% - seven years later (2008), i.e. it reached the same levels 7 years later than in Germany. What if we plot the share of wind power in both countries but shift the time scale by 7 years so that 1994 for Germany would be aligned with 2001 for the UK? This is shown in the figure below (note the logarithmic vertical scale which is most suitable to depicting exponential growth and the different horizontal time axes for Germany and the UK).
Wind power generation (log scaleas share of national electricity supply in 2005 in Germany (1994-2016) and in the UK (2001-2016). Data by IEA (2017) processed by V.Vinichenko.
The figure shows that in the 14 years between 1994-2007 the development of wind power in Germany was very similar to that in the UK in the 14 years between 2001-2014. Both closely followed exponential trends (dotted straight lines in the figure). The average annual rate of growth of wind power in the UK was 31% and in Germany - 28%. In 2007, Germany produced ≈28 times more wind power than in 1994; in comparison, in 2014, the UK produced ≈29 times more wind power than in 2001. After 2007, the growth of wind power in Germany has slowed to 9%/year on average (dashed orange line in the figure). It is difficult to say whether the UK will repeat the same pattern as in terms of technology diffusion 'it is not there yet'.
These observations mean that after a certain point the development of wind power in both countries followed very similar trends. In our data analysis we have traced this 'certain point' as far back as 1994 in Germany and 2001 in the UK. After these years, the development of wind power in both countries could be seen as following its natural evolution accurately predicted by the classic technology diffusion theory and was apparently not affected by different political or other conditions in both countries (e.g. Germany's "Energiewende", or the UK's renewed commitment to nuclear power). There is no point in even looking for political or other explanations for the differences of wind power expansion in the UK and Germany after 2001, since there was no such difference, beyond natural technological evolution.
What does require explanation, is why wind power took off (achieved a point of 'no-return' triggering exponential expansion) in Germany sometime in the mid-1990s and in the UK - only in the early 2000s. The deployment phase of new technologies, when it grows exponentially, is usually preceded by the formative phase, when it exists in a small niche isolated from the general market. The quantitative analysis used here for the deployment phase would not work at the formative phase when new technology grows erratically, driven by unpredictable and often disruptive innovation and delayed by frequent failure. The question of what hastened wind energy take-off in Germany and slowed it down in the UK in the mid-1990s deserves a special investigation. Another analysis is required to explain why the growth of wind power in Germany slowed down after 2007.