**1. Introduction**

Increasing energy demand stimulates economic growth (represented by the gross domestic product (GDP), but energy consumption also causes greenhouse gas emissions. One can see that GDP allows comparing the dynamics of economic development over time and on a cross-country basis but recently one can hardly assess economic growth without attributing attention to the consumption of natural resources and preserving the environment. In was in the past decades that the increasing attention to global warming and climate change has focused on the relationship between environmental pollutants, energy consumption and economic growth [1–3]. In order to effectively control greenhouse gas (GHG) emissions and ensure the sustainability of economic development, it is important to better understand the relationships between greenhouse gas emissions, energy consumption and economic growth [4–6]. The energy consumption for each mode of transport is calculated as direct energy (consumption of fossil fuels and electricity during transport) and cumulative energy (including the energy consumed during the entire production process (exploration, extraction, transport and production of fuels). The emissions are calculated as carbon dioxide (CO2) equivalent to taking into account the total GHG potential of emissions from the combustion of fossil fuels. With regard to the above, one can differentiate between the direct CO2 equivalent, which occurs at the place of energy conversion, and the cumulative CO2 equivalent, which takes into account the entire production process (exploration, extraction, transport and production of fuel) [7,8].

One of the illustrative examples is the transport sector that, together with heating, constitutes one of the mean areas where profound electrification based on the renewable energy source (RES) became an overall target many governments worldwide committed to. Even though we do not base the results of our paper on this sector and do not analyze it or consider its in-depth implications, a simple reference can be useful here. In general, greenhouse gas emissions from the transport sector rose from around 146 megatons of carbon dioxide equivalents in 2000 to 174 megatons in 2017 [9,10]. Greenhouse gas emissions from passenger cars rose from 81 megatons in 2000 to 94 megatons in 2017. The largest increase from 50 megatons in 2000 to 72 megatons in 2017 is for freight vehicles [11]. It is important that the company monitors both intensity and overall emissions. To keep the indicator set small, only the GHG intensity is included in this toolkit. Carbon offsets or other emissions trading programs are not considered in this toolkit.

With all of the above, it has to be mentioned that the EU is on the forefront of electric transportation with an ambitious plan to operate around 250 million electric vehicles (EVs) by 2025, which represents an effective transition to the climate targets [12]. However, the effective reduction of energy consumption and greenhouse gas emissions that the electric transportation was envisaged to entail, seem to require proper energy policy and careful planning [13]. The plans for transport electrification meet lots of obstacles and introduce several paradoxes. For example, one can observe that very often the electricity for powering the electric vehicles (EVs) is produced at the coal power stations, which creates a negative overall impact for the environment. Thence, it becomes apparent that the transition to clean electric transport should proceed along the lines of green-to-green paradigm and have to be considered from the point-of-view of the sustainability spectrum. It is not easy to provide a justified opinion on how to avoid the negative impact on the environment related to electromobility implementation. One of the possibilities would be the new advances in EV technology using alternative energy sources or improvements in battery storage technology that would allow to transfer large amounts of energy over large spaces.

Overall, one would probably agree with us that economic development and growth in today's globalized and cumbersome world should be based on the optimal managemen<sup>t</sup> of natural resources that would not induce any harm or burden for the future generations to come and to their natural environment. Thence, the attention should be focused on the resource managemen<sup>t</sup> that would both ensure the global competitiveness of economies without compromising their economic growth and well-being.

This paper focuses on the renewable energy sources in the EU 2020 target for energy efficiency in the two EU Member States, Czech Republic and Slovakia. We scrutinize the EU national energy efficiency targets for 2020 (which represents an important energy policy task, as Newbery at al. [14] demonstrate) and compare them with those of the two countries in question. Moreover, we employ the Auto Regressive Integrated Moving Average (ARIMA) model to obtain the forecasts for whether the 2020 targets can be achieved.

#### **2. Energy Consumption and Greenhouse Gas Emissions**

Household energy consumption is the main reason for the sector's observed greenhouse gas emissions [15,16]. Although the ratio of total energy consumption to GHG emissions is direct, the contribution of electricity consumption to GHG generation compared to other fuels used primarily for thermal purposes is much more significant compared to their share of total energy [17,18]. This can be backed up with the fact that the average carbon intensity (in gCO2-e/kWh) is internationally used in calculating greenhouse gas (GHG) emissions from the electricity system, and the role of GHG in this system is highlighted in many reports and studies covering a wide spectre of countries, including China, Iran as well as other countries (see, e.g., [19–21]).

One of the main advantages of efficiency improvements is that they slow down the growth in energy consumption and reduce greenhouse gas emissions [22,23]. Energy intensity is the ratio of energy consumption per activity unit (such as floor space and GDP). In a way, energy efficiency is a measure of how effectively energy is used for a specific purpose and an important way of decarbonization [24–26]. The energy evaluation makes a major contribution to ensuring that users are where improvements are needed. Lots can be achieved in an energy assessment, from the disclosure of energy consumption to waste identification and efficient energy use. Efficient use of energy is still an important national and international topic in the discussion of political measures, both in European Union and abroad [27,28]. The assessment of energy efficiency in different countries is important for each country. To improve the efficiency of anyone's home, one should first carefully consider her or his options. An audit assesses electricity bills, insulation, heating and cooling systems, electrical systems as well as devices to determine how much energy your house uses and where energy is wasted. Following the recommendations and specially devised strategies can save 5% to 30% of the electricity bill [29,30].

Speaking about the penetration of the renewable energy sources into the traditional electricity and power systems, one has to look deeper into the specifics. In many countries, hydro sources are often needed to generate energy for almost all fuels and technologies to generate electricity, and energy is needed to treat and transport both water and wastewater [31–33]. A fascinating case study on the subject is the state of California in the United States with its large water supply systems (which require a lot of energy for pumping) that moves water from the relatively humid northern areas of the state to the drier and more populated southern region (including the major metropolitan areas of Los Angeles and San Diego) [34]. Conversely, the majority of the natural gas used in the water system is used for water heating on the consumer side of the water meter. Savings varied significantly across the state's hydrological region, with the largest savings in the populous south coast region (237,200 mg) and the lowest savings in the sparsely populated North Lahontan region (1400 mg) [35]. Since the savings in electricity and greenhouse gas emissions are calculated directly from the water savings, the results of these calculations showed a similar spatial variation.

When it comes to the debate of promoting renewable energy sources (RES) for the future electricity and power systems, one has to consider all possible alternatives [36–38]. Apart from the traditional renewables there are also some carbon-based alternatives to oil (e.g., methane hydrates and the conversion of coal into methane gas, or the use of oil reservoirs and shale oil), but other interesting options present themselves too [39–41]. One of them is the microbial fuel cells (MFCs) that convert biochemical to electrical energy [42–48]. MFCs can be used in biomass-based energy production, even though a plethora of technical challenges has to be solved before they will be practical for renewable energy production [49–51]. Nevertheless, their applications and possible deployment show that there are many less explored possibilities of using renewables in electricity generation, many of those not well-known to the general public or less explored by the researcher who might not be aware of all the possible implications for energy security and energy policy they might present [52–56].

All in all, energy consumption and greenhouse gas emissions constitute an important problem that all the world's largest economies are facing today, However, one can also see that this might be a political, rather than a climate protection, energy efficiency or economic issue. World leaders and important stakeholders are interested in re-election or maintaining their leading positions. Therefore, they want to make sure economic stability and growth are delivered at all costs. However, in the same time they have to face the commitments of tackling the climate changes and global warming, as well as introducing more renewable energy sources into the generation of power and electricity. Somehow, a balance should be reached and maintained to keep both the voters and the international partners satisfied. The European Union (EU) is in a specifically difficult position in this situation due to its complex structure, which lacks the traits of the federal state, and has a complex decision-making process as well as evaluation and acceptance procedures.

#### **3. Europe 2020 Strategy and the 3** × **20 Climate and Energy Package**

One would probably agree with is that EU plays a crucial role in the world as a powerful actor and leader in sustainable economic growth. The EU serves as a role model for more governments and actors when it comes to taking real and effective action [57]. The search for ways to increase and improve the use of renewable energies should not stop in 2020. Countries should continue to focus on this area in the coming decades and shape the next steps together. The first deadline for adoption of the package in Parliament was March 2009. However, there have been protests in some countries regarding the modalities to achieve these goals, particularly as a result of the economic and financial crisis that has led to tough negotiations between countries. The European Council of the 11th and 12th of December 2008 finally adopted the package but changed the original measures.

Various EU countries have many issues with meeting their energy efficiency and consumption obligations. For example, the French governmen<sup>t</sup> admits failing to meet its climate change commitments. In 2017, France achieved 16.3% of its energy consumption from renewable sources, compared to its 23% target for 2020. Wood and hydropower are the main sources of green energy in France, ahead of biofuels [58,59]. The legislative proposals concern energy efficiency, the design of the electricity market and the governance rules for the Energy Union.

The climate package recognizes energy poverty as a major challenge in Europe and, with these proposals, aims to protect vulnerable consumers through targeted socio-political and energy-efficient measures [60,61]. In the package, one can see only minimum requirements for total energy efficiency. They regulate the maximum permissible energy consumption per floor area or room volume in new and existing buildings.

There are also provisions such as energy performance certificates, indicating the energy consumption of an existing or new building or a new building unit, and usually classify it in steps that differ in terms of energy consumption per square meter [62,63]. The certificates are issued by certified energy auditors and must be issued publicly, for example in advertisements for the sale or rental of buildings.

In this regard, the policy stipulates that regular maintenance can lead to significant operational improvements and recommends combining these inspections with certifications. The number of charging stations has been growing faster and faster than the number of EVs that could use them, and their installation is becoming increasingly profitable for electricity suppliers. In order to boost the market for cleaner vehicles, the EU Parliament and the Council agreed in February 2019 to amend the directive on the promotion of clean and energy-efficient vehicles [64]. The directive stipulates that authorities that procure vehicles (e.g., for public transport) must take their CO2 emissions and the emissions of other pollutants into account. The EU emissions trading system includes emissions from more than 11,000 power plants and industrial plants and, from 2013, emissions from aviation. Around 40% of total EU emissions are covered by the regulation [65]. In addition to the EU27, Croatia, Iceland, Norway and Liechtenstein are also part of the ETS. When the EHS was introduced in 2005, it was the first trading system for greenhouse gases. As already mentioned, the EU should achieve its

overall GHG target. The EEA's projections show that it will cut its greenhouse gas emissions by six percentage points above the 2020 target with existing measures and by seven percentage points by adopting additional measures. Since 2016, five EU countries have actually increased their greenhouse gas emissions compared to 1990. Careful monitoring was applied to the primary energy consumption in order to assess progress in energy efficiency in terms of goals and policies for the European Union and its Member States. In 2009, the Europe 2020 Strategy was adapted [66]. It includes very important and timely targets set for the whole European Union are as follows:


• moving towards a 20% increase in energy efficiency (from 2005 levels).

Table 1 shows the national energy efficiency targets for 2020 for the EU28, Czech Republic and Slovakia.


Note: Mtoe—million tonnes of oil equivalent; \*1—compared to 2005 levels; \*2—share of renewable energy in gross final energy consumption; \*3—absolute level of energy consumption in 2020 (Mtoe) as notified from Member States in 2013, in the NEEAP 2014, annual reports or in separate notifications to the European commission in 2015 and 2016 (Mtoe); \*4—compared to 1990 levels.

A little explanation should be made here for better clarity of the explanation of our empirical model and its main results and implications that are presented in the next sections. As opposed to final energy consumption, primary energy consumption refers to energy that has not been subject to any conversion or transformation process. Energy intensity represents the amount of primary energy consumption per unit of GDP. The energy intensity indicator depends on the industrial structure of the economy and thus is not an exact proxy for energy efficiency in the EU Member States.

Moreover, several more methodological issues should be explained about the energy intensity (EI), gross inland energy consumption (GIEC), gross domestic product (GDP) and their relationship. All of the above can be expressed in the formula that follows:

$$EI = GIE \text{\textquotedblleft GDP} \tag{1}$$

where:

> EI—energy intensity; GIEC—gross inland energy consumption; GDP—gross domestic product.
