tirsdag 9. mai 2017

The Great Transition

This blog post comments on Lester Brown's book The Great Transition, Shifting from Fossil Fuels to Solar and Wind Energy.

I start with a micro-summary of Lester Brown's view on the alternatives to fossil fuels.

Lester Brown is skeptical about nuclear power, mainly due to cost, long planning and construction time to build new nuclear power plants, problems with nuclear waste, and the probability for accidents like those in Chernobyl in 1986 and Fukoshima in 2011. The share of nuclear power in the global electricity production has fallen from 18 percent in 1996 to 11 percent in 2013.

Lester Brown is also skeptical to increase the use of biomass for energy, mainly because cropland should be used for food production and because intact woods are important for biodiversity.

Lester Brown argues that wind and solar energy is the best alternative to fossil fuel energy. He presents many cases where solar or wind accounts for a significant share of the electricity production. Examples of such cases are wind in Denmark and wind and solar in Germany.

Based on what I have read in other sources I fully agree with Lester Brown's viewpoints on the alternatives to fossil fuels.

Lester Brown often refers to the capacity of the wind and solar power plants. The capacity is power measured in watts (W). For wind and solar it is the power output when the sun shines and the wind blows. The consumption is energy measured in watt hours (Wh). 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'. The wind and solar capacity factors are much less than for most other sources. We must have that in mind when we evaluate wind and solar capacities. I will in this blog post only discuss consumption, which is energy and measured in watt hours.

As mentioned in the micro-summary, Lester Brown presents many cases where solar or wind accounts for a significant share of the electricity production. But I miss an overview of the shares of the global energy sources and how they have evolved in the last decades. The rest of the blog post focuses on that.

The book was finished at the end of 2014, and it uses data available up till then. The book often refers to 'BP Statistical Review of World Energy June 2014'. It contains data up to and including 2013. Two new versions of this BP report are published since then, and the last one contains data up to and including 2015. I will present some figures based on this last report, 'BP Statistical Review of World Energy June 2016'. The figures are made based on the data in the spreadsheet that BP publishes together with the report.

Figure 1 shows the shares by fuel type of the global energy consumption. The total consumption is 13.15 Gtoe (Gtoe is billion tons oil equivalents). The renewable sources hydro, wind, solar, biomass and geothermal sum up to 1.26 Gtoe, i.e. 9.6 percent of the total.

Figure 1: Global Energy Consumption 2015 by fuel. Data from BP.

The figure shows that coal, oil and natural gas still dominate globally as energy sources. Their shares sum up to 86 percent. Wind and solar account for less than 2 percent of the total energy. That's about half of the share of nuclear energy. 

Electricity will play an increasingly important role in the future. It will gradually replace fossil fuels in many areas such as transportation. The next figures will therefore concentrate on electricity.

Figure 2 shows the world electricity consumption from 1985 up to and including 2015.

Figure 2: World electricity consumption by source. Data from BP.

In 2015, the share of electricity generated by fossil fuels was almost twice as large as the shares of the other sources combined. But the consumption of electricity generated by fossil fuels fell from 2014 to 2015, while all the other sources increased.

Figure 3 zooms in on electricity from nuclear and renewable sources in Figure 2. 

Figure 3: World electricity consumption from nuclear and renewables. Data from BP.

The contribution from nuclear peaked around 2005. Before 2005 the contributions from hydro and nuclear were about the same, but after 2005 the contribution from hydro became larger than that from nuclear. Hydro increased and nuclear slightly decreased.

The contributions from wind and solar increase exponentially. The increase in wind and solar is much larger than for the other sources when measured in per cent, as Figure 4 shows. 

Figure 4: Change in electricity consumption by source. The change is measured in percent relative to the consumption in the previous year. Data from BP.

The increase measured in TWh from 2014 to 2015 is larger for both wind and solar than for the other sources.

It is impossible to predict how the electricity consumption by source will evolve in the future. 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 2015 under the assumption that the changes measured in percent relative to the previous year will be as they were in the years 2013 to 2015, both for the total consumption and for all sources except from fossil fuels. The consumption by fossil fuels is set equal to the total consumption minus the sum of the other sources. The result is shown in Figure 5.
Figure 5: A projection of the energy consumption by source for the years 2016 to 2027.

The legend shows the annual increase in per cent for the total consumption and for all sources except for fossil fuels. The consumption by fossil fuels will decrease due to the strong exponential growth in wind and solar. By 2027 the consumption by solar will be larger than by fossil fuels, and the consumption by wind will be the same as by fossil fuels.

Lester Brown writes in his book that 'The Energy transition [to wind and solar] is here'. Figure 1 shows that in 2015 the consumption by wind and solar was less than 2 per cent of the total consumption. Figure 4 shows that in the last years wind and solar have increased much stronger than the other sources. Figure 5 shows that, if this continues for the next decade, the shares of wind and solar will dominate in a decade. Yes, the energy transition to wind and solar has started. 

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