There is no doubt that by 2100 the world will have abundant, cheap carbon-free energy available. Coal will only be seen in museums, and the use of oil and natural gas is falling dramatically. Technological processes will inevitably result in this, even if public policy does not facilitate it.
However, to prevent potentially catastrophic climate change, a carbon-free world economy should be in place by the middle of the century. This is also feasible, but only with the right strategic visions and strong political support. Electricity will dominate the global energy system of the future. At present, however, electricity accounts for only 20 percent of final energy demand, and direct fossil fuel use still dominates transport, building heating, and heavy industry. The energy needs of most economic activities can be met by electricity, and many of them become much more efficient as soon as they are electrified.
Internal combustion engines typically convert 60 to 80 percent of the energy they use into wasted heat and convert only 20 to 40 percent of the kinetic energy needed to drive vehicles. In contrast, electric motors have efficiencies of over 90 percent. Furthermore, their production is so simpler that within five years, the cost savings generated during production will offset the cost of batteries, making electric vehicles cheaper compared to diesel and gasoline cars. Similarly, electric heat pumps can produce more than 3 kilowatt hours to heat buildings using just one kilowatt hour of electricity. No gas boiler can produce more than 0.9 kilowatt hours with the same amount of energy input.
Although battery-powered electric motors will play an increasing role in short-haul flight and shipping, batteries are too heavy to provide power for long-haul flights or intercontinental shipping within a few decades. However, marine engines can also burn ammonia instead of petroleum, and ammonia can be a carbon-free fuel if it is provided from hydrogen produced by electrolysis of water using electricity from renewable energy sources. In addition, synthetic aviation fuel can be produced from hydrogen and carbon dioxide extracted from the air. Hydrogen, when used as a fuel or as an important chemical input, will play a major role in the decarbonisation of heavy industries (such as steel and chemicals).
Even if we do not assume fundamental technological innovations, we can certainly achieve by 2050 that electricity will cover 65-70 percent of final energy needs in the global economy and hydrogen, ammonia or synthetic fuels another 12-15 percent. Bioenergy and fossil fuels should cover only about 20 percent of total energy consumption. With such a significant restraint in the use of fossil fuels, carbon capture could provide a true carbon-free economy. Furthermore, such widespread electrification would bring huge environmental benefits by eliminating air and noise pollution and unwanted or wasted heat generation that is unavoidable by burning fossil fuels in vehicles, gas boilers and industrial processes. Building such an economy will require an annual global power supply of about 90,000 terawatt hours compared to the current level of 23,000 terawatt hours. All this must be ensured in a carbon-free manner, but this goal is also clearly achievable. The Sun radiates eight thousand times more energy to Earth each day than would otherwise be needed to meet humanity’s daily energy needs.
Ninety thousand terawatt hours of solar energy could be generated using less than 1.5 percent of land areas (this rate would be less than 0.5 percent if we could also use water surfaces). The cost of solar energy has fallen by 85 percent in the last ten years, and in many parts of the world solar energy is already cheaper than coal – and by the middle of the century it will be even more affordable. The cost of wind power has also dropped rapidly, and nuclear fusion power could be a commercially viable technology within two decades. Battery costs have fallen by more than 80 percent since 2010 and are likely to halve again by 2030, while a recent report showed that the cost of electrolysis is likely to fall soon. Many other energy storage and energy demand management technologies also promise to answer the main question of the renewable energy system: what to do if the sun is not shining and the wind is not blowing.
These developments make it inevitable that by 2100 there will be plenty of cheap and completely clean energy in the world. However, we may not be able to prevent catastrophic climate change. The use of fossil fuels is still rising and global warming will reach 3 degrees Celsius by 2100 compared to pre-industrial levels – if the situation does not change – well above the 2 degrees Celsius level set out in the Paris Climate Agreement.
Furthermore, although the cost of solar and wind energy has decreased, capacities need to be increased three to four times in order to produce 90,000 terawatt hours of clean electricity per year by 2050. The macroeconomic cost of such efforts is by no means enormous: the level of investment needed to build a carbon-free economy by 2050 would be 1-1.5 percent of global GDP per year. However, effective government measures are needed to accelerate these processes. Policies to this end must begin with the recognition that electrification and the significant use of hydrogen are the only way to achieve carbon-free economic prosperity. Governments need to set ambitious targets for increasing renewable energy, and in some cases nuclear, capacity, while using auctions to secure private sector contributions at the lowest possible cost.
The strategy for road transport should aim to eliminate internal combustion engines completely from the roads by 2050 at the latest. This requires a much sooner ban on the marketing of new vehicles with internal combustion engines. In addition, carbon pricing is needed to make decarbonization of the industry economical. Finally, governments should support new technologies that have helped to rapidly reduce the cost of solar photovoltaic technology, wind turbines, and batteries through initial subsidies. With such measures, the world could build a carbon-free economy fast enough to reduce the rate of climate change to manageable levels. However, without the right measures, a carbon-free economy would be too late.