1. Energy and energy transitions throughout history
Energy underlies all the major economic changes that have occurred throughout history, especially those of the two last centuries. The three great industrial revolutions that transformed the world over the last 250 years were powered by a variety of energy sources. Each revolution was accompanied by changes and diversification of the energy mix on the one hand and the appearance of new sources of energy on the other, both contributing to distinguish one revolution from the next.
The First Industrial Revolution took place between the end of the XVIII century through the XIX century, powered by coal, which made the use of the steam engine possible. The Second Industrial Revolution occurred during the first half of the XX century and was driven by the use of oil to power internal combustion engines, while the Third Industrial Revolution, which began in the second half of the XX century and continues until this day, has seen the surge of electronics and Information and Communication Technologies, driven not only by oil, but also by gas and the nascent use of renewable energies. At one time, it appeared that this Third Industrial Revolution would be powered by nuclear energy, but the high cost of installation and maintenance of uranium-fueled plants, coupled with the grave accidents of Three Mile Island in 1979, Chernobyl in 1986 and Fukushima in 2011 have consigned this energy source to a secondary role in many countries that once desired to rely on its use. This is one of the reasons why the energy mix has not changed substantially since the years 1970-1980.
The distribution of the various energy sources used by humans since the start of the XIX century to the present is shown in the illustration:
Since the 1980s, “new” renewable energies (wind and solar, mainly) have been gradually added to the global energy mix alongside hydraulic power, which emerged at the beginning of the XX century. These new sources of energy should play a key role in the trend toward diversification of the energy mix and help to solve the dilemma between an unsustainable energy model and ever-increasing global demand.
2. The energy dilemma: depletion of fossil fuels and population growth
At present we are facing a “perfect storm” in the realm of energy, brought on by a lethal combination of depletion of fossil fuels and the increase in energy demand due to population increase and improvements in the quality of life of a significant part of the same.
Maximum consumption of fossil fuels, defined for oil as Hubbert’s peak has been/will be reached between 2000 and 2020. As shown in the illustration, it has become imperative to find new energy sources to replace fossil fuels in no more than 40-60 years; that is, in our children’s lifetime:
Historically, population and income increases have been the driving forces behind energy demand. As seen in the illustration above, the population has increased five-fold since 1900, income has increased by a factor of 25 and energy consumption has increased by a factor of 10. The connection appears obvious: more people with higher incomes means an increase in production and higher energy consumption.
We are therefore faced with a scenario where fossil fuels are in a phase of decline, while the population and energy consumption do not cease to increase. What should be done? The only possibility is to implement an energy transition that both satisfies increasing energy demand and prevents continuous irreversible damage to the environment.
3. Technologies for energy transition: the time for renewable energies
At present, the only energy sources in our reach that can replace fossil fuel-based energy are renewable sources. The most significant of these, due to their increased use, development and technological breakthroughs, are “new” renewable energy sources: wind, solar photovoltaic and thermosolar, to which we should add traditional energy sources, such as hydraulic and biomass energy.
All of these, especially those considered new sources, should be considered as replacement technologies that were the object of scientific curiosity in the 1970s and 1980s but have now become a necessary and indispensable part of the solution to the problem of energy stated in the previous section of this article.
Wind power was the first renewable energy source to be used on a large scale in the energy industry. Total wind power installed globally is shown in the following illustration: at the end of 2017, this total reached 540 GW. As is the case in the use of solar photovoltaic energy (progressive installation shown in the same chart), the main disadvantage is its sporadic nature, which makes it somewhat unpredictable. Developing appropriate and large-scale storage systems is essential to increase the value of wind and sun-generated electricity. Nonetheless, wind power generation at present has already demonstrated its usefulness in the energy mix of numerous countries, including Spain and its future competitiveness with fossil fuels can only improve in the coming years.
4. Obstacles for energy transition
There are three main obstacles to be overcome for swift energy transition.
- The first one is the amount of energy currently provided by non-renewable sources and the size of the energy-generating infrastructures that have been built over the years. Due to their immense scale (over and above the TW of installed power), any transition is and will continue to be slow.
- The second obstacle is economic, since power plants require a multi-million dollar investment and a decades-long life cycle. Thus, the energy mix for 2030-2040 will be heavily affected by the decisions made now. Beyond 2050, innovation, research and development, as well as government policies, will have an ever-increasing impact on changes to the current energy mix.
- The third obstacle is scientific. While energy density of non-renewable energy sources is high, wind and solar power energy densities are very low. Therefore, replacing non-renewable energy with renewable energy involves substituting high-energy density and low-cost (at least until now) sources with low-energy density and high-cost sources. In addition, the general opinion regarding the cost of renewable energies is predominant; although renewable energy prices have dropped significantly, their high cost continues to be voiced as an impediment to large-scale installation.
As mentioned previously, oil, coal and natural gas currently account for 85% of the energy mix worldwide. Even at a high and sustained rate of growth in the use of renewable energies, their participation in primary power production at 20 years from now would still be under 10% of the total, simply because the current starting point is very low.
Changing the energy model is a global challenge, witnessed by the enormous investment being made by the world’s major industrial countries to enhance energy transition toward a sustainable and fossil fuel-independent energy mix. The change is inevitable, already in progress in numerous countries and those are the first to learn to adapt will lead the change and be able to export their ideas and products to the rest. The energy industry will change gradually toward renewable energy and the transition period will be determined to a large degree by both public and private investments made in these energy sources.
A little over a year ago (January 9, 2017), former president Barack Obama published an article in the prestigious journal Science with the eye-catching title “The irreversible momentum of clean energy“. This change cannot be stopped, but can be accelerated in various ways by the decisions that are made now.
Professor of Electronics at Universidad Complutense, Madrid and member of the Spanish Royal Physics Society