The uncertainty of transition times

The uncertainty of transition times

Giuseppe Sammarco
Historically, every new energy source has taken decades to increase its market share over previous sources. Will renewables be the exception to the rule?

The energy market is changing: new policies, technologies and sources are prompting us to embark on a long journey towards a new world, an “energy transition” to achieve a sustainable consumption model and solutions to tackle global warming and climate change. An important and widespread debate is already ongoing on these topics, the terms and concepts of which will be examined in this series of articles. Here you have the sixth one.


In the previous article, after analyzing the major mega-trends driving the energy transition of this century, we asked some questions about the timeframe of this complex journey to a new energy paradigm. This is one of the main issues we will start to address in this article.

To understand the future, it is always useful to learn from the past. To discuss what happened in the fourth transition – that of the last 150 years which brought us to the current energy paradigm – we’ll start with a very interesting analysis by Vaclav Smil in one of his publications.

The study is summarized by the graphs in Figure 1. There are four graphs: one for coal, one for oil, one for gas and one for modern renewable energy sources (wind, solar, geothermal, and sustainable bio-energy). Coal, oil and natural gas are the main sources of energy on which the last energy transition was based. In this order, they subsequently reached commercial maturity and entered the world energy market, gradually increasing their share of consumption.

Each graph shows the evolution over time of the percentage of the individual source out of the total world consumption of primary energy, starting from once the source has reached 5%.



For example, coal reached 5% of consumption in 1840 (the starting figure of the curve) and took around 35 years to reach its 25% share, before exceeding it subsequent years. Of course, even reaching a share of 5% is no simple task: it took nearly 100 years prior to 1840 (this information is not shown in the graph).

Petrol arrived next, which reached the 5% share in 1915 after more than 50 years of very slow growth. It took approximately 40 years to reach 25% of the total energy consumption.

Lastly comes natural gas, which reached the 5% share in 1930 (after nearly 60 years of growth) and took around 55 years to reach 25%.

Of course, these were indeed other times, and technological advances were not as dynamic as they are now and did not allow for quick changes of direction. However, it must also be said that world energy consumption was much lower than today, and it was easier to increase market shares with limited increments of the quantity supplied.

Indeed, if we carefully examine these first three charts, an initial observation can be made. The first three graphs become gradually less curved as we move from the first to the third. That is to say, as the years pass and the world energy system increases in size, more and more time is needed for the new source to increase their market share over the previous ones (and partly replace them). The years of the three fossil fuels, rising from 5% to 25% (35 for coal, 40 for oil and 55 for gas) would seem to confirm this observation.

Let us now look at the fourth graph to the right, which relates to modern renewable energy sources (wind, solar, geothermal and sustainable bio-energy). Many believe that this century’s energy transition will be based on a rapid replacement of fossil fuels with solar or wind energy, since these sources are widespread and, importantly, free from carbon dioxide emissions and pollutants. Yet their level of penetration, as we have seen, is still low, accounting for just 3% of the total consumption of primary energy in 2012 (Smil’s data also includes sustainable bio-energy; in 2018 the share may have exceeded 4% and approached 5%). If these new energy sources confirm the rule of the flattening curve, they may be expected to take even more time than in the past to reach the share of 25% and higher. Even assuming an average dissemination speed between that of coal, oil and natural gas, if history repeats itself for these new energy sources, it would take several decades to achieve high consumption levels and displace existing sources.

The issue of transition times is surrounded by uncertainty and differing views. Indeed, some argue that the particular features of new renewable sources will ensure that the laws of the past no longer apply: the trend of their exponential growth will remain long-term and growing market shares will be gained extremely quickly. Yet there is also some debate over whether new renewable sources are the only way of decarbonizing and whether the timeframes and effectiveness of the transition should be measured based solely on their distribution. In the next and final article, we’ll be going into greater detail on these debates.