A Global Assessment: Can Renewable Energy Replace Fossil Fuels by 2050?

Jerry L. Holechek

Hatim M. E. Geli

Mohammed N. Sawalhah

3 and

Raul Valdez

New Mexico Water Resources Research Institute, New Mexico State University, Las Cruces, NM 88003, USA

Department of Lands Management and Environment, Prince Al-Hasan Bin Talal Faculty for Natural Resources and Environment, The Hashemite University, Zarqa 13133, Jordan

Department of Fish, Wildlife and Conservation Ecology, New Mexico State University, Las Cruces, NM 88003, USA

Submission received: 26 February 2022 / Revised: 31 March 2022 / Accepted: 8 April 2022 / Published: 16 April 2022

Abstract

Our study evaluated 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. We 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, we 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 . Our 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.

1. Introduction

Climate change is now considered the major threat to the future of humanity by leading scientists [1,2,3,4]. Globally, the 10 hottest years on record have occurred since 2004 with the five hottest years in the 2015–2020 period [5]. Although 2020 was the second hottest year on record worldwide, for Europe it exceeded the previous high in 2018. Since 1980, extreme climatological events involving temperatures, droughts, and forest fires have quadrupled, whereas meteorological events such as extreme storms have doubled [6,7]. In the United States (US) more than twice as many billion-dollar disasters occurred in the 2010–2019 decade compared with the 2000–2009 decade [5]. In 2020, an all-time high of 22 weather and climate disasters exceeding a loss of one billion dollars occurred in the US shattering the previous record of 16 for 2011 and 2017 [5].

So far, the global temperature increase compared with pre-industrial times (before 1850) has been near 1.2 °C with 1.1 °C since 1900 [1,8]. Of deep concern is that the increase in temperature is accelerating and is projected to be at the 1.5 °C level within 15 to 20 years if emissions of greenhouse gases (GHG’s) are not drastically reduced [1,8]. Even with the 2015 International Paris Agreement to reduce GHG emissions, global temperatures have continued to increase due to the world’s increased use of fossil fuels and deforestation [1,8,9]. With continued reliance on fossil fuels as the primary energy source, a 3 °C or more temperature increase is predicted by the end of this century [1,10]. In October of 2018, the United Nation’s International Panel on Climate Change (IPCC) put the world on notice that exceeding a 1.5 °C temperature increase will be catastrophic with consequences of unprecedented flooding, drought, rising sea level, heat waves and famine [1,2]. The biggest concern is that a tipping point or threshold may soon be crossed because of accelerated climatic warming and instability imperiling a large portion of the human population [3,4,7,10,11,12].

In October of 2018, the IPCC [2] warned that CO₂ emissions must be reduced 45% over 2010 levels by 2030 and reach net zero by 2050 to contain the global temperature increase to 1.5 °C. Various benefits of limiting temperature increase to 1.5 °C as opposed to 2 °C under the 2015 Paris Agreement were given. Very importantly, limiting global temperature increase to 1.5 °C would provide human societies and ecosystems more time to adapt to the process of climate change. Selection of approaches for achieving this objective has yet to be identified. Some experts have proposed rapid and widespread changes in the world economy involving energy use, land use, transport, industry, agriculture, and construction [13,14,15]. Because these changes would be very disruptive to the heavily globalized world economy, a less drastic approach focusing on development of renewable energy (primarily wind and solar) and enhancements in energy efficiency (decoupling) has been emphasized since the 2015 Paris Agreement by the primary CO₂ emitters (i.e., China, the United States, the European Union, Japan, Russia, India, Brazil) [16,17].

A common concern is that persistent growth in the human population requires an ever increasing consumption of energy and other natural resources nullifying gains made from efficiency improvements in resource use and expansion of renewable energy production [13,18]. Another major concern, beyond CO₂ emissions, is that the fossil fuels on which the world still depends on for over 80% of its energy needs are finite and will be critically depleted within 50 years at current use levels [9,13,19].

Our foremost goal in this conceptual analysis and review paper is to evaluate the effectiveness of the present global approach to climate stabilization (post 2015 Paris Agreement) in terms of reducing GHG emissions and containing temperature increase to 1.5 °C (e.g., see [17]). In order to evaluate the potential of renewable energy to replace fossil fuels by 2050, we developed and modeled nine scenarios involving three different levels of energy demand and three different levels of renewable energy development. The BP ‘Statistical Review of World Energy (2021)’ annual report was used as our database [9]. We focus on the replacement of fossil fuels with renewable energy sources because this is considered to be the most practical single pathway to climate stabilization when physical, financial, political, and environmental factors are all considered [1,9,15,16,17]. In 2020, fossil fuels, renewable sources, and nuclear power accounted for about 83.1%, 12.6%, and 4.3% of world energy use, respectively [1,8,9]. Within the renewable category hydropower dominated (6.86%), followed by wind (2.90%), solar (1.54%), and other renewables (1.26%). Bioenergy (~0.55%) and geothermal (~0.13%) energy are primary components of the other renewables category. Wind and solar energy are considered to have the most potential for rapid, large-scale expansion but at some point, they will probably be constrained by metal ore and land availability [15,16,17]. Although hydroelectric, biofuels, geothermal, and tidal are important renewable energy sources, at present their expansion potential is low due to factors involving either their restricted geographic distribution, large land requirements, lack of availability of undeveloped sites, and/or unsolved technical issues related to their implementation [15,16,17].

Our secondary objective involved the assessment of the roles and capabilities of seven other pathways to achieve net-zero GHG emissions from fossil fuel use when used in combination with renewable energy sources. These seven pathways included energy efficiency improvements (decoupling); energy conservation measures; carbon taxes; more equitable balancing of human well-being and per capita energy use; cap and trade systems; carbon capture, utilization, and storage (CCUS); and nuclear power development. It is generally recognized by energy authorities that some combination of these pathway in conjunction with renewable energy will be needed to achieve net-zero CO₂ emissions [9,15,17]. However, actual quantitative evaluations on how they might be applied have been lacking.

Our third objective was to derive fair per capita energy use values for developing and developed countries. Human happiness and well-being are related to per capita energy use. The average minimum per capita level of energy use needed for a materially ‘Decent Living Standard’ for different world regions is derived. This meta-analysis establishes some guidelines on what might be fair, realistic per capita energy use targets for individual countries under conditions of a restricted global energy supply that the world is increasingly confronting. Therefore, it is a critical consideration in developing policies by individual countries that will be equitable, fair and result in high global cooperation in the transition away from fossil fuels.

Our fourth objective is to provide an overview of the role fossil fuels have played in enabling the unprecedented human population increase, improvement in living conditions, increase in human longevity, and technological advances since 1850 when they became widely adopted as the primary energy source. Conversely, we point out the role fossil fuels have played in environmental decline over the last 50 years focusing on climate change. We emphasize the fossil fuels (coal, oil, natural gas) are finite in quantity, nonrenewable and will be severely depleted within 50 years. We consider in some detail six basic reasons why replacing fossil fuels with renewable energy resources over the next 30 years will be a tremendous challenge with an uncertain outcome. We consider this review very important because the range of issues and challenges we discuss relating to replacement of fossil fuels with renewable energy sources are generally not well understood by political leaders, educators and the public at large [15,17].

In terms of organization, we begin the body of our paper with a review of how the use of fossil fuels have impacted the human population and its quality of life. Next, we consider the two major challenges with a fossil fuel-based economy: depletion and climate change. Then, we begin answering the question: Can renewable energy meet world energy demand in 2050? We first focus on how much expansion will be needed in primary renewable energy sources (hydro, wind, solar) and nuclear power using BP data [9]. The results from our modelling exercise are presented in tabular form and discussed. A discussion is given of six reasons why the transition to renewable energy will be difficult and uncertain. We identify and discuss seven additional pathways that can be used in combination with renewable energy development to achieve net zero carbon dioxide emissions. The issue of what level of annual per capita energy use is needed for a ‘Decent Living Standard’ in different world regions is explored. In our conclusion we provide a perspective on feasibility of achieving a complete and equitable conversion to zero emissions by 2050 through implementation of the combination of eight pathways discussed in our paper.

The meta-analysis uniquely articulates on the potential renewable energy solutions to address the climate change problem in a way that can be easily understood by policy makers, scientists, educators and concerned citizens alike. Our paper emphasizes and shows a combination of eight pathways will be needed to attain net-zero carbon dioxide emissions from fossil fuels. Successful use of these pathways will necessitate major lifestyle changes and taxation policies whose purpose must be well understood to garner necessary public support. Our paper is among the few that address the challenge of a more constrained energy supply coupled to rising energy demand in the context of social equity. It provides guidelines on per capita energy use for a ‘Decent Living Standard’ for different world regions which should be helpful in policy decisions. Although our focus is on renewable energy, we recognize that biological and geoengineering solutions may also play critical roles in managing the problem of climate change.

2. Methods and Data

The data used in this analysis included recent estimates of global energy resources and use, and socioeconomic and climate change indicators. Data on human population and demography were obtained from the UN [20,21] and Worldometer databases [22]. Socioeconomic data that include per capita energy consumption was obtained from the BP Statistical Review of World Energy 2021 [9,23], Our World in Data-Energy Use per Person [24]. Data on Gross Domestic Product (GDP) per capita were obtained from the UN GDP per capita reports for 2021 in US dollars [25]. Data on human development and happiness were obtained from the UN Human Development Report 2019 [26] and World Happiness Report 2019 [27], respectively.

Data on world reserve of crude oil, natural gas, and coal were obtained from BP [9]. Global CO₂ concentration and emission was obtained from the WMO and USGCRP [8,12] and IPCC [1]. World energy use data were obtained from the IEA, BP [9,28] and EIA 2019 which also include data on energy use from fossil fuels. World energy consumption projections and demand scenarios were obtained from EIA 2019, IEA, and BP [9,28,29].

To evaluate the potential of renewable energy to replace fossil fuels by 2050, we developed nine scenarios involving three different levels of energy demand and three different levels of renewable energy development. We used the BP ‘Statistical Review of World Energy (2021)’ annual report as our data base [9]. Our demand scenarios for 2050 were world energy demand held constant at the 2020 level (556.6 EJ), demand at 1.25 times the 2020 level (695.4 EJ), and demand at 1.5 times the 2020 level (834.9 EJ) as projected by the IEA [18]. Our supply scenarios involved annual renewable energy increase at 1x, 3x and 6x the 2020 level (2.69 EJ) multiplied by 30 years plus the current production of renewable energy (31.71 EJ). For the six scenarios involving either a 3x or 6x renewable energy increase, we also assumed nuclear power realistically could be doubled and hydro energy expanded by 31% over 2020 levels.

where Renewable refers to the different renewable energy production scenarios; y refers to the number of years until 2050; scenarios of average production with current production of 2.89 EJ as of 2020, and 3 times of current production of 8.67 EJ and 6 times of current production of 17.34 EJ; global energy consumption based on 2020 estimates of 31.7 EJ.