tirsdag 30. mai 2017

China's electricity transition

This blog post shows that the transition to wind and solar energy in China's electricity production has started.

China is the world's largest emitter of greenhouse gases, and its inhabitants are suffering from air pollution caused by the burning of fossil fuels. China is determined to improve on these topics, and it is interesting to see how this has affected the country's electricity production. China publishes both its capacity and its production of electricity on the China Energy Portal. The portal is updated with data up to and including 2016. All plots in this blog post are based on data from that portal.

First some basics about electricity. Capacity is max power that may be produced. It is measured in watts (W). Production is energy that actually is produced. It is measured in watt hours (Wh). I present power with the unit GW, which is one billion watts, and energy with the unit TWh, which is one billion kilo watt hours. The capacity factor is a 'unitless ratio of an actual electrical energy output over a given period of time to the maximum possible electrical energy output over the same amount of time'.

Figure 1 shows the Chinese electricity capacity since 2006. Back then there was almost no contribution from wind and solar. In 2016 the contributions from these sources were significant.

Figure 1: China's electricity capacity

The actual contribution from wind and solar is not as positive as Figure 1 gives the impression of, because wind and solar both have smaller capacity factors than the other sources have. Figure 2 shows that.

Figure 2: The capacity factors of the Chinese electricity sources
The capacity factors of wind and solar are about 20 percent and 13 percent, respectively. Nuclear has a capacity factor larger than 80 percent, showing that nuclear power plants produce electricity almost all the time.

Figure 3 shows the Chinese electricity production by source. The contribution from thermal power plants, mostly coal, dominates. But we see, very interestingly, that the production from the thermal power plants has not increased in the last four years, despite that Figure 1 shows that the thermal capacity has increased significantly in the same years. This is why the capacity factor of the thermal power plants has decreased during the last years, as shown in Figure 2. The explanation to this must be that the thermal power plants are not run at their full capacity when there are surplus of electricity from wind and solar.

Figure 3: The Chinese electricity production by source

It is impossible to see the details of nuclear, wind and solar in Figure 3 due to the crude vertical scale. The next figure zooms in to see those details.

Figure 4: The previous figure, The Chinese electricity production by source, zoomed in to see the details of nuclear, wind and solar.
Figure 4 shows that the production by wind has become larger than the production by nuclear. It also shows that the production by solar increases exponentially by almost 100 percent a year. Wind and solar have increased from almost nothing to significant levels during the last six years.

Figure 5 shows the percent increase in the Chinese electricity production by source.

Figure 5: Percent change in the Chinese electricity production. The changes are relative to the production in the previous year.

The solar production increased by more than one hundred percent annually in 2012, 2013 and 2014. In 2015 and 2016 it increased by almost 68 percent each year.

It is impossible to predict how the electricity consumption by source will evolve in China. It depends on both policies and on technologies. But we can project what will happen under given assumptions. I will now project the consumption in the years following 2016 under the assumption that the changes measured in percent relative to the previous year will be as they were from 2015 to 2016, both for the total consumption and for all sources except thermal. The consumption by thermal is set equal to the total consumption minus the sum of the other sources. The result is shown in Figure 6.

Figure 6: A projection of the electricity production by source in China. 

The legend shows the annual increase in percent for the total production and for all sources except for thermal. Thermal will decrease due to the strong exponential growth in wind and solar. By 2023 the production by both solar and wind will be larger than by thermal.

It is now cheaper to build new electricity plants based on wind and solar than based on nuclear and fossil fuels. Wind and solar are therefore often regarded as disruptive technologies. The next blog post will deal with the transition to disruptive technologies, both in general and specifically for wind and solar power.

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