Risks for a Successful Transition to a Net-Zero Emissions Energy System

The year 2021 brought a significant increase in ${\mathrm{CO}}_2$ emissions despite the rapid growth of new renewable energy sources (RES) installations being commissioned. Globally, this increase amounted to 6% year-on-year, and in the largest EU economy, Germany, as much as 4.5%.

Figure 1 shows the increase in the ${\mathrm{CO}}_2$ concentration in the atmosphere and the cumulative worldwide increase in RES capacity put into use. It is disturbing that, despite the exponential growth of new RES capacities, ${\mathrm{CO}}_2$ emissions are still growing. It is clear that stopping the growth of ${\mathrm{CO}}_2$ emissions still requires enormous material and financial investments. This poses a very serious threat because, as the authors of [1] point out:

“... a strong transition to RES would imply a rematerialization of the economy with the potential to counteract future efficiency improvement trends [1]”.

The rematerialization of the economy takes place when the consumption of materials is again linked to economic growth, meaning there is a greater need for manual labor, heavy industry, the opening of new mines, a greater need for energy and, consequently, more ${\mathrm{CO}}_2$ emissions. This is especially dangerous because it can lead to an energy trap, meaning that the system needs more energy just to produce more energy.

In [1], the authors show that exceeding 50% RES energy generation in the energy–electric system by 2060 may be very risky for the entire EU energy system. This is mainly due to the fact that RES technologies are characterized by high operating instability (depending on weather conditions), relatively short lifetime, very low energy density, and the need to store energy. As a result, the level of the Energy Return on Investment (EROI) coefficient, defined as [2]:

$$\mathrm{EROI}=\frac{\mathrm{usable}\mathrm{energy}\mathrm{the}\mathrm{plant}\mathrm{returns}\mathrm{during}\mathrm{its}\mathrm{lifetime}}{\mathrm{all}\mathrm{the}\mathrm{invested}\mathrm{energy}\mathrm{needed}\mathrm{to}\mathrm{make}\mathrm{this}\mathrm{energy}\mathrm{usable}}$$

(1)

is too low, and practically for all RES technologies (if we take into account energy storage) is below the level required for economic viability [2].

EROI is well correlated with quality-of-life factors such as the human development index (HDI), health expenditure, female literacy, rate of underweight children, and gender inequality [3]. Compilation and comparison of the results of the works [1,2,3] clearly shows that too fast and intensive switching to renewable energy sources may significantly deteriorate quality of life and not significantly reduce greenhouse gas emissions to the atmosphere.

At this point, one should also look at an equally disturbing fact; the low capacity factor of wind and solar installations. For wind installations, this ranges from 0.1 to 0.25 depending on the geographical location, while for wind turbines this is from 0.2 to 0.4; however, the highest is achieved on offshore installations, which are much more demanding in terms of technology and investment.

Table 1. Capacity factor of selected wind and solar power plants.

Plant & Location	Installed Capacity, MW	Energy Source	Energy Produced GWh/Year	Capacity Factor
AWEC, USA	1550	wind	3189	0.235
Whitelee, UK	539	wind	1257	0.27
Capricorn Ridge, USA	662.5	wind	1927	0.33
Limon, USA	600.6	wind	2066	0.39
Margonin, Poland	120	wind	279	0.27
Ivanpah, USA	377	solar	865	0.26
Genesis, USA	250	solar	621	0.28
Jaworzno, Poland	5	solar	5	0.11

shows some examples of large-scale RES installations with their capacity factors.

The low capacity factor means that there is a need to build large-scale and high-capacity energy storage facilities, which, apart from pumped hydroelectric energy storage (PHES), are still unavailable. If we optimistically (and unrealistically) assume that it is possible to build a PHES facility with an energy conversion efficiency of 75% everywhere, it means that for each 1 GW of energy installed in conventional energy, 5 GW of renewable energy installations are needed to replace it (assuming an equal share of solar and wind installations).

For example, for a large EU country such as Poland, which currently has 40 GW of installed capacity in the electricity system, 200 GW of renewable energy installations and hundreds of GWh of energy storage would be needed to replace it. In addition to investments worth hundreds of billions of USD, one should recall the very high requirements of land use, caused by the very low energy density of renewable energy technologies.

Wind turbine and solar panel farms require 25 and 3 ha, respectively, per 1 MW of installed capacity [4]. Continuing the considerations for a country similar to Poland, this means a land demand of 27,000 km${}^2$, which corresponds to 8.8% of the country’s area. It is worth noting that Poland has a relatively large number of national parks, the total area of which is 3300 km${}^2$.

At this point, it should be added that renewable energy installations must be duplicated by fast-starting power plants, so in the power system, large powers must also be kept in full readiness at all times, covering the demand for electricity in the event of too-low wind speeds and solar radiation. In practice, this task is performed by gas power plants (simple gas cycle), which need large amounts of fuel (natural gas), and their low efficiency causes significant ${\mathrm{CO}}_2$ emissions to the atmosphere.

It should be noted that RES installations are very sensitive to severe weather conditions. Wind farms do not operate when the wind speed exceeds cut-out speed, and in the event of icing, their production can drop by up to 80% [5]. According to the IPCC 2021 report, the upcoming climate changes will also result in an increase in severe weather conditions, which will have a significant negative impact on RES energy production and will increase the operating costs caused by damage to these installations.

Climate change is already having a very negative impact on wind energy production, as the global average wind speed has decreased by 5% and this decline is expected to continue. A similarly unfavorable feedback is visible in the production of electricity from solar energy, because with an increasing ambient temperature, the efficiency of solar energy conversion decreases from 0.3 to 0.5% per degree Celsius. As a consequence, an increase in the average temperature of the Earth by 2 degrees Celsius can lower this efficiency by 1%, and the power generated by solar farms may decrease by 5% [6].

The above statement is not intended to discredit renewable energy technologies; it is only intended to draw attention to numerous pitfalls and dangers that are not widely discussed. Furthermore, it must be recognized that significant savings and reductions in ${\mathrm{CO}}_2$ emissions can be achieved here and now through more efficient energy utilization.

A good example would be to stimulate the transition to efficient energy technologies in household appliances, which are common in all households. The Polish division of Home Appliance Europe (APPLIA), based on the example of Poland, estimates that in a large European country, household appliances consume about 11 TWh of electricity per year, and only switching to energy-saving refrigerators would save 1 TWh of electricity per year. This is equivalent to the electricity needs of around 450,000 European households.

Taking into account all the above considerations, the most advantageous technology that enables one to achieve climate goals while securing energy needs is nuclear power. It has EROI up to 100 the highest of all currently existing technologies, the longest lifetime, the lowest land use and the lowest environmental impact [2].

It is worth adding that the development of nuclear energy also stimulates the development of fusion technologies, which, according to current forecasts, should be commercially available in 20–30 years. The International Thermonuclear Experimental Reactor (ITER) experiment is due to be ready in 2025 and is to show that it is possible to obtain, in a controlled manner, 10 times more energy from nuclear fusion than the energy needed to maintain it. This seems like an undeniable indicator that the real game changer is just around the corner. Therefore, it is worth asking whether it is not better to transfer some of the expenditure on renewable energy to the development of nuclear energy and research and development of thermonuclear power generation.

Such an approach may be more effective in reducing ${\mathrm{CO}}_2$ emissions, will ensure the availability of energy at an appropriate level, and in the case of the commercialization of fusion technologies, will even allow the removal of ${\mathrm{CO}}_2$ directly from the atmosphere.