Holechek and 3 co-authors, evaluated in mid-2022 the effectiveness of using eight pathways in combination for a complete to transition from fossil fuels to renewable energy by 2050. These pathways included renewable energy development; improving energy efficiency; increasing energy conservation; carbon taxes; more equitable balancing of human wellbeing and per capita energy use; cap and trade systems; carbon capture, utilization, and storage; and nuclear power development.
They used the annual ‘British Petroleum statistical review of world energy 2021’ report as our primary database. Globally, fossil fuels, renewable (primarily hydro, wind and solar), nuclear energy accounted for 83%, 12.6%, and 6.3% of the total energy consumption in 2020. To achieve zero fossil fuel use by 2050, they found that renewable energy production will need to be increased by up to 6-fold or 8-fold if energy demand is held constant at, or increased 50% from, the 2020 energy demand level.
Constraining 2050 world energy demand to a 25% increase over the 2020 level, improves the probability of achieving independence from fossil fuels. Improvements in energy efficiency need to accelerate beyond the current rate of ~1.5% per year. Aggressive application of energy conservation policies involving land use and taxation could potentially reduce world energy use by 10% or more by 2050. Our meta-analysis shows that the minimum level of per capita energy consumption that would allow 8 billion people to have a ‘Decent Living Standard’ is on average ~70 GJ per capita per year, which is 93% of
the 2020 global average. Developed countries in temperate climates with high vehicle-dependency needed ~120 GJ per capita year−1, whereas equatorial countries with low vehicle-dependency needed 30 GJ per capita year−1.
They authors' meta-analyses indicated replacement of fossil fuels with renewable energy by 2050 may be possible but will require aggressive application of all eight pathways, major lifestyle changes in developed countries, and close cooperation among all countries.
[After discussing renewable energy uses, the authors turned to evaluating nuclear power, which we will review in the following.]
Nuclear Power Development
Prior to the March 2011 Fukushima nuclear disaster in Japan, nuclear fission power was widely considered a primary solution to fossil fuel depletion and global warming. It can potentially provide tremendous quantities of energy with very little atmospheric pollution and relatively low use of land [see references:54,55,59,76]. Since 2011, global generation of nuclear power has been in a slight downward trend that may be reversing [9,64]. Over 150 nuclear reactors are planned for the future which would increase nuclear power output by about 50%. Besides almost no atmospheric pollution, nuclear power has advantages of no intermittency problem unlike wind and solar, it is generally cheaper than wind and solar, it is not as materials intensive as wind and solar, and it requires much less land than wind, solar or biomass per kwh (kilowatt hour) produced [54–56,59]. Compared with wind power, nuclear power land requirements per kwh are only about 2–3% and compared with solar power of about 12–13% [71,94]. Corn ethanol production is the most land-intensive of all energy alternatives requiring about 100 times more land per kwh produced than nuclear power [71,94]. By some estimates nuclear power, if aggressively developed, could meet 50% of all global energy needs within 10 years and nearly all greenhouse gas targets within 30 years [95,96].
Part of this strategy would involve using nuclear power to make synfuels from CO2 and hydrogen to be used as fuels in airplanes and trucks [55]. There is
much optimism that the effectiveness of nuclear power could be greatly increased through [SMRs] and breeder reactors which can consume most of the spent fuel left as waste from conventional reactors [59,76].
Although nuclear power has potential as a partial fossil fuel replacement in climate mitigation, it has important drawbacks that involve supplies and cost of uranium [not a problem], high plant construction costs [should be considered a long-term investment], long time requirements for plant construction, high water requirements for cooling purposes [that is the reason for sitting near the oceans and rivers], hazardous waste disposal problems [not a problem], terrorist sabotage vulnerability [not a problem], and major concerns over human health and safety [demonstrated safest energy source] [41,56,70]. Thus, nuclear power is not viable for many parts of the world because annual water surpluses must be available for cooling [56]. Another problem is that under continuing global warming water sources needed for nuclear plant cooling are becoming less reliable due to more droughts and altered river flows [97]. This necessitates periodic shutdown of some nuclear plants. France, which derives 77% of its electricity from nuclear power, is now experiencing this problem [97]. The authors noted that there have been recent improvements in nuclear plant safety [55,76].
When comparing its potential use, it seems unlikely nuclear power will play the primary or decisive role in climate change mitigation, but it can be an important part of the solution.
CONCLUSIONS
The authors concluded that the main objective of this analysis was to assess the capability of renewable energy sources to globally replace fossil fuels by 2050. Climate change, which is recognized as the biggest threat to humanity, is a systemic problem that is tightly linked to global human population growth and increased per capita use of energy derived from fossil fuels. Scientific evidence directly links the use of fossil fuels to increased emissions of greenhouse
gases that quickly and irreversibly change world climate resulting in global warming.
Fossil fuels in 2020 accounted for 83% of world energy consumption compared with 86% in 2015 when the Paris Climate Agreement to limit CO2 emissions was signed. Renewable energy (primarily wind and solar) accounted for 5.7% of total energy consumption in 2020 compared with 3.3% in 2015.
Hydroelectricity and nuclear energy showed little change accounting for about 7 and 4%, respectively, in both years. Our analysis showed that in order to attain zero fossil fuel use by 2050, the annual rate of increase in renewable energy production will have to expand 6-fold if energy demand is held constant at the 2020 level and 8-fold if energy demand increases 50% due to increased population and per capita consumption. Added renewable energy is not yet replacing fossil fuels because of growth in energy demand due to increases in population and per capita consumption. It only met 42% of increased energy demand in 2019. In 2020 world energy demand declined 4.3% due to the COVID-19 pandemic but growth in new demand is expected to resume
by 2023.
Under a scenario of a 25% increase in world energy demand, a 6-fold increase in renewable energy, a doubling of nuclear power, a 31% increase in hydropower and limited use (6.5%) of fossil fuels with carbon capture and storage (CCUS), the authors determined that renewable energy could replace conventional use of fossils fuels by 2050. The biggest uncertainties in this scenario are whether renewable energy can be increased 6-fold and whether demand increase over the 2020 level can be constrained to 25%. In order to meet a 50% energy demand increase, nuclear power and fossil fuel use with CCUS would have to be greatly expanded, [which is underway].
The authors explored what minimum level of per capita energy consumption would allow 8 billion people to have a ‘Decent Living Standard’ (DLS). Our meta-analysis indicates a global average annual per capita energy consumption of ~70 GJ met these criteria, which is 93% of the current world average (75 GJ). For a DLS in developed countries in temperate climates with high vehicle dependency about four times more energy (120 GJ/year) is needed as in equatorial countries with little vehicle dependency (30 GJ/year).
The authors' review and study identified six major challenges related to transitioning from fossil fuel to renewable energy that include energy density, intermittency, location, transportation bottlenecks, environmental impacts, and land availability. It further examined how a combination of eight pathways could lead to net-zero emissions from fossil fuels.
These pathways include renewable energy development; incentives for increased energy efficiency (decoupling); energy conservation incentives; carbon taxes; more equitable balancing of human wellbeing and per capita energy use; cap and trade systems; carbon capture, storage, and utilization (CCUS); and nuclear power development.
Restricting the use of fossil fuels through carbon taxes and cap and trade policies are the primary policy tools to lower their use. However, their implementation is likely to slow or halt economic growth and cause a financial crisis. Therefore, we suggest they be implemented gradually and moderately. Aggressive application of energy conservation policies involving land use and taxation could potentially reduce global energy consumption by 10% or more over the next 30 years.
In summary the authors' analyses indicated that it is theoretically possible to achieve UN climate stabilization goals by 2050 if energy demand is constrained to 25% or less above the present level, renewable energy sources are developed at 6 to 8 times the present rate, energy efficiency and conservation measures are much more aggressively applied, nuclear power is expanded by 30% or more, developed countries (especially the US) reduce their per capita energy use by 40% or more, and carbon capture, utilization and storage methodologies are widely applied. The authors readily acknowledged achieving these goals in practice will depend on some technological breakthroughs and a high level of international cooperation that are both uncertain and may not be possible. The primary assumptions in our analyses are that wind and solar energy development will not be constrained by availability of land and metal ores. [The anticipated increase in SMRs and other new technology in nuclear power, may meet the energy requirements in the U.S. and around the world at the expense of fossil fuels over time]
The authors recognized that their assumptions may not hold. In this context they considered aggressive development of adaption as well as mitigation measures would be highly prudent.[whatever that means ...]
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