**1. Introduction**

Recent decades have demonstrated an intensive development of theories, concepts and approaches related to various aspects of sustainable development such as circular economy [1], waste managemen<sup>t</sup> [2], cleaner production [3], environmental economics [4], etc. Within these approaches, a special place is occupied by the fight against global warming, which is caused by human activities, namely by higher emissions of man-made greenhouse gases, mainly CO2 [5].

As a result of multiple environmental studies carried out in relation to the above concepts, it has been found that the energy sector is one of the main sources of greenhouse gas emissions among all types of human activity [6]. This fact has become one of the main reasons for combatting the already existing energy system [7], which is founded on hydrocarbon resources (HCR).

Examples of this combatting are seen in the political arena, where it is openly declared that the era of hydrocarbons is over, and we need to switch to alternative energy sources as quickly as possible. This assertion can be found in the declarations of the G7, the World Bank, the European Investment Bank and many other international corporations that restrict access of production and geological

survey projects to the investment capital. An example of large-scale "anti-hydrocarbon" policy based on environmental taxes (Figure 1), can be seen in Europe, which has been continually criticized by the industry companies due to worsening investment climate and lower production profitability [8].

**Figure 1.** Average carbon tax rate in Europe, Euro/t. CO2 [9].

It is remarkable that the real activities of these international corporations significantly differ from their declared policy, as shown, for instance in [10–12]. For example, despite declarations, they continue to provide financial support for hydrocarbon energy projects, although indirectly.

An increase of oil production volumes in the United States of America (USA) by 8410 thous. bbl/day for the period of 2015–2018, which is twice as high as total global increase in production over the same period, is a clear example of such two-track policy (Figure 2). At the same time, a major part of USA production is shale oil, which is much more cost-intensive than conventional oil. Additionally, according to the data of the State Energy Department [13], the USA has been implementing an extensive program in support of gas hydrates studies, which is related to prospective HCR.

**Figure 2.** Global and USA oil production dynamics. Based on BP Energy Overviews.

Additionally, the collapse of oil prices in March 2020 has triggered a proactive purchase of cheap Arab Light oil by the USA and Urals oil by China to refill strategic reserves. These examples clearly show that there is no intention to decrease our activity in the hydrocarbon energy sector.

The real state and trends of the energy sector can be seen when considering forecasts of leading global companies, for example British Petroleum (BP), over different years (Table 1).


**Table 1.** The comparison of BP Energy Overviews (EO) for the period of 2014–2019.

The Table shows that the forecast proportion of HCR in the global energy balance varies slightly despite milestones with respect to their substitution for alternative energy sources. The highest decrease is shown by coal (−6%), while the proportion of oil went up by 1–2%. The share of natural gas demonstrates minor fluctuations, contributing as little as 1–2%. Taken as a whole, and based on the latest BP report, the proportion of HCR (oil, coal and natural gas) in the global energy balance will amount to nearly 76% in 2035, which is equal to 12.9 bln toe. This means a guaranteed demand for HCR, as well as tougher competition and intensification of the struggle for access to them, resulting in HCR earning a status as a geopolitical resource that can be seen even today.

A somewhat di fferent forecast based on plotting "Hubbert curves" is provided in [14], whereby the production peak of oil will occur in 2009–2021, of gas in 2024-2046, and of coal in 2042–2062. It should be noted that these results should be treated with some care, since Hubbert curves may be modified when a ffected by economic and technology factors. Nevertheless, similar results have been obtained by other authors [15,16]. Despite some variations within the ranges in years, all of the above forecasts came to the same conclusion: the production peak of the majority of HCR is still ahead of us.

It should be understood that all of the above scenarios expect that, within the next few years, oil and gas production volumes will increase due to fields with complex subsurface conditions or located in adverse climatic conditions. Pursuant to [17], the cost for development of such reserves can be 3–4 times greater than the conventional reserves of fields in the Middle East (production cost below 10 \$/bbl). Taking into account current prices for oil (around 30 \$/bbl), the development of such reserves may become economical in the case of state support or where there is intensification of technical progress rates in the production of hydrocarbons, incl. due to the digitalization of operating activities [18].

At this point, the main question is whether global regulators will be able to create the conditions required for reaching and passing the HCR production peak with regard to sustainable development principles [19], or whether industries will survive amid discriminatory financing of potentially attractive but presently non-competitive technologies.

This study presents the analysis of alternatives o ffered today for substitution of HCR and an assessment of their viability. The further contents of this article are organized as follows: Section 2 describes the main critical comments for HCR; Section 3 reviews the main alternative energy technologies and their strengths and weaknesses; Section 4 gives a consolidated description of the current position of HCR and a detailed analysis of liquified natural gas (LNG) development prospects as one of the most prospective HCRs; Section 5 contains conclusions and reasoning of the author.

#### **2. Climate Change and Public Image of HCR as a Source of CO2 Emission**

Climate change is definitely a significant issue on a global scale. There are two opposing opinions about its nature. The first opinion is that the main reason for Global Warming is the increase in the emission of technogenic greenhouse gases, mainly CO2. This is the most widespread point of view, which is partly explained by possibility of studying this phenomenon. To date, there have been many compelling studies [20], proving that mankind is provoking climate change on the planet through its activities. This has been reflected in strategic intergovernmental agreements aimed at decreasing the rate of temperature growth, such as the Paris agreement, which, however, may not be enough [21].

The main concern is that human activity may lead to the passing of a tipping point, after which climate stabilization will become impossible, even if the emissions of technogenic greenhouse gases were to be reduced [22]. Moreover, it has been shown [23] that there are many tipping elements that could lead to irreversible climate consequences. This creates confusion in the process of defining the strategic aims of global environmental activities and the ways to achieve them [24].

According to the International Energy Agency (IEA), volumes of CO2 emissions in 2019 amounted to 33 Gt, which is the peak value of all time. In addition, a significant part of these emissions is formed as a result of HCR use [25]. Multiple studies have been dedicated to the assessment of indirect losses [26] from the use of various HCR, for example: the use of land for the construction of power plants, accidents at production enterprises, servicing of nuclear waste sites, the higher probability of military conflicts due to rights of access to raw material resources, and many others. In accordance with several obsolete assessments, such factors may increase the cost of using energy resources by 0.29 \$ (wind energy sector)–14.87 \$ (coal) per 1 kWh [27]. However, to be relevant and useful, such assessments should be conducted on a regular basis and for di fferent regions, with respect to the specifics of local legislation.

The second position on Global Warming suggests that the main drivers of climate change are not related to human activity, but are connected with natural reasons. For example, NASA believes that global warming is mainly caused by changes in the Earth's orbit related to the sun. This opinion is based on the Milankovitch theory [28], which was initially ignored by the scientific community, but after the release of the study of Hays et al. [29], proving its validity in many aspects, much more attention has been given to it. However, it is extremely di fficult to push this idea forward, due to objective technical and technological reasons.

Another example is related to the influence of natural disasters. In accordance with [30], the annual volumes of CO2 emissions caused by volcanic activity may amount to almost 0.05–0.3 Gt per year. Another CO2 source is fires. For example, in 2010, forest fires in Russia resulted in CO2 emissions of more than 0.25 Gt [31]. Following the results of [32], the annual volume of CO2 emissions caused by forest fires in Russia amounted to more than 0.12 Gt for the period of 1998–2010. Forest fires in Indonesia in 1997 produced from 0.81 to 2.57 Gt of CO2 [33]. CO2 emissions as a result of burning peatlands in South-Eastern Asia are estimated at 0.637–2.255 Gt per year [34]. These are some examples of natural factors influencing the higher volume of greenhouse gas emissions, while forest fires occur regularly, especially on peatlands. In addition, according to [35], the entire volume of carbon accumulated in the atmosphere is less than the basis point of total carbon on the planet, while 99% is underground. Emissions of other greenhouse gases (CH4, NOx, etc.) have been studied to a very limited extent [36–39], making it quite complicated to assess their volumes in a substantiated way.

The main critical argumen<sup>t</sup> towards the volumes is that they make up less than 10% of total man-made CO2 emissions. However, it should be taken into account that volcanic activity, as well as fires, has taken place for thousands of years, while mankind only started to emit such CO2 volumes in recent decades. At the same time, it is obvious that additional technogenic emission is not a way to balance the global carbon cycle [40], and the contribution of mankind has become more visible in recent centuries [41].

Based on this, society is fed the idea that we should immediately reject usage of HCR without details about the dependence of our economic stability on these resources. Such an approach is questionable, because, in fact, we have to find a consensus on the need to improve the environmental safety of the processes in this industry and to support its development.

Therefore, if the significance of HCR in the economy is indisputable, the political rhetoric in this field and the attempts to create a strongly negative perception of all HCR among the public, without attention given to the di fferences between fuels and between the technologies of their production and

use, is a point of debate. Hence, it is a very important question: "Should we continue a discrimination policy towards the HCR due to their contribution to a global carbon emission, or should conditions for the sustainable development of this industry be created?", since forecasted HCR production shows that they will play a significant role in the global economy for several decades in the future.

#### **3. Alternative Energy Technologies. Problems and Prospects**

Technological transformations, especially within such a key area as the energy sector, go hand in hand with the transition to a new technological order, which is a very long-term process that may take up to several decades [42]. The creation of conditions for the implementation of these transformations and transitions with minimum losses will be of high importance, both for the environment and the economy, i.e., in view of the sustainable development principles [43]. The variety of terms defining sustainable development in modern publications does not change its common nature, offered in 1987 [44], while the principles and methods of sustainable development mainly depend on a regulator, i.e., on politics and policy [45], and may be implemented on national, regional, and local and lower levels [46,47].

The entire list of factors influencing the implementation of transformations at every level can be roughly divided into the technology-readiness level, the regulatory-readiness level, and the market-readiness level [48]. However, despite the fact that the focus of key policy provisions can be made on the basis of climatic (Kyoto Protocol) and technological (Paris Agreement) considerations, the objective fact is that there are no reliable scientific results showing how exactly technological factors influence policy development [49]. In other words, the extent of the influence of technology readiness on the formation of policy and, as a result, on the readiness of the regulatory framework, is unknown.

Elimination of this gap in knowledge requires an interdisciplinary approach [50] with studies executed by international scientific groups. This is related to a need for deep modernization of the already established global infrastructure, and requires some strategic decisions on the support of certain technological niches (technological groups) to be supported by scientifically substantiated and realistic recommendations on the determination of overall vector of activities [51] and specific measures. For further analysis, the most promising technological niches were selected from among those available today [52–54], and are reviewed below.
