The level of renewable energy use and economic development of a country, as separate indicators, have an influence on the level of energy resource imports, but the mutual impact of renewable energy sources and gross national product on the growth or decrease of energy imports dependency have not been studied. Therefore, the aim of this study was to evaluate the energy security of European countries by taking into account the consumption of renewable energy sources and the economic development of the countries. In particular, the article examines the relationship between energy import dependency, gross domestic product (per capita), and renewable energy sources in 27 countries in the European Union. Regression analysis of data on EU countries for 11 years (from 2011 to 2021) was used to determine the non-linear influence of gross domestic product and renewable energy use on energy import dependency. This influence was simulated by a second-order regression equation. The analysis of the equation for extremes made it possible to conclude that with a share of energy from renewable sources at the level of 32%, the economic development of a country does not require an increase in energy import dependency, and with larger values of energy from renewable sources, a decrease in energy import dependency may occur. In addition, according to the analysis of the obtained mathematical dependence, it is recommended that countries with a gross domestic product of up to 10,000 euros per capita use renewable energy sources at the level of 40%. For the countries with a domestic product of up to 30,000 euros per capita should use renewable sources at the level of 50%. For countries with a gross domestic product of more than 30,000 euros per capita, renewable energy sources at a level of more than 55% is recommended. A high level of renewable energy use will allow a country to increase its gross domestic product without a significant increase in energy import dependency, and at the level of renewable energy sources of more than 32%, an increase in gross domestic product does not actually lead to an increase in energy import dependency. An increase in the use of renewable energy sources above 40% of the total consumption of energy resources in a specific country, in particular, and in the European Union, in general, will ensure an increase in energy security and an increase in the level of energy independence.

The aim of this study was to assess the possibilities to use brewer’s spent grains (BSGs) left over from beer production for energy purposes, and to determine its calorific value and chemical composition. The research materials were samples of wet spent grain from a brewery in Poland. Three samples, that are different in ingredient composition, were examined. The examined samples of BSGs were characterised by humidity that is typical for this product (approx. 77–80%). Convective drying of the spent grain contributed to a reduction in the water content in the biomass to below 10%. Samples of dry spent grain that were examined contained a similar amount of ash (3.8–4.1% d.m.) and organic matter (91.0–91.9% d.m.). All the examined spent grain samples demonstrated similar volatile matter content—approx. 77.8–78.7% d.m. and calorific value—approx. 15.6–15.9 MJ/kg. The estimated calorific value for wet samples (approx. 1.4–2.0 MJ/kg) indicated that it is necessary to lower water content in the biomass in order to improve its energy properties.

Soil compaction (SC) is one of the most damaging degradation processes. The effects of compaction are closely related to crop losses and GHG emissions due to additional fuel use. It is therefore important not only to correctly monitor the condition of the soil and the restoration of damaged soil but also to understand the costs of excessive exploitation of soil and individual risks in different countries and continents. A model of equations has been developed to assess the effects of compaction that can be used on a national or even single farm scale. However, for its further application, more data should be collected. Based on the data available in the public domain, the damage caused by compaction was compared between Ukrainian (UA) and Lithuanian (LT) scenarios as these countries have a similar situation but different levels of soil resource management. Soil characteristics, such as soil types and predisposition to compaction, depending on its type, were assessed in both countries. The main parameters used to estimate the damage due to SC were: yield loss; additional fuel consumption; losses of N, P, K fertilizers, water pollution, and flooding; erosion; and GHG emissions. The results reveal potential annual losses due to compaction of around EUR 27 million for Lithuania and around EUR 1.6 billion for Ukraine. Expected potential average losses per hectare of arable land are about EUR 49 ha⁻¹ y⁻¹ for Ukraine (33.9 million ha or 56.76% of the total area) and about EUR 13 ha⁻¹ y⁻¹ for Lithuania (2.11 million ha or 33.77%). Potential crop losses are one of the costliest consequences of compaction. They could cost about EUR 1 billion annually for Ukraine and about EUR 10.7 million for Lithuania. Moreover, the additional use of fuel and the associated GHG emissions can probably take away EUR 180 million (UA) and about EUR 4 million (LT) each year.

The article deals with the study of a balanced agroecosystem on the production of crop products, livestock products and biofuel with respect to its energy autonomy with ensuring its environmental safety. The structure of straw use in agroecosystem and its influence on humus balance and level of electric and thermal energy supply is investigated. The balance of humus in crop rotation was chosen as the criterion of ecological safety. The criterion of energy autonomy is the level of providing the agroecosystem with electric energy and thermal energy through the use of biofuels of its own production. The coordination of environmental safety, energy autonomy and economic efficiency was taken as the basis for the functioning of the agroecosystem. In a balanced agroecosystem on the production of crop products, livestock products and biofuel up to 41% of straw should be used to maintain the balance of humus in the soil. Up to 22% of straw can be used to produce heat and electricity for own needs. Up to 37% of straw can be used to produce electricity for sale according to the green tariff.

Multi-crop plants (fibrous hemp, maize, and faba bean) can potentially be an alternative to wood biomass pellets, but there is no detailed knowledge to support the suitability of this biomass for solid biofuel production. The aim of this study is to analyze and justify the suitability of multi-crop plant biomass for the production of biofuel pellets and to assess the environmental impact of burning them. This paper presents studies of physical-mechanical, thermal, and chemical characteristics of biofuel pellets from multi-crop plants and emissions during their combustion under laboratory conditions. The main parameters of the produced pellets were determined according to international standards, which are detailed in the methodology part. The length of the produced pellets ranged from 17.6 to 26.6 mm, and the diameter was about 6 mm. The density of wet pellets varied from 1077.67 to 1249.78 kg m⁻³. The amount of ash in the pellets varied from 5.75% to 8.02%. Determined lower calorific value of all pellets was close to 17.1 MJ kg⁻¹. The lowest CO and C_xH_y emissions were determined when burning MIX2-1 pellets (biomass of the binary crop); their values were 572 and 29 ppm, respectively. The lowest content of CO₂ was determined when burning S-Mz pellets (mono crop biomass), and it was 3.5%. The lowest NO_x emissions were also determined when burning the pellets of this sample, with a value of 124 ppm. Research results show that multi-crop plants are a suitable raw material for the production of solid biofuel, the burning of which does not cause negative consequences for the environment.

Biohydrogen production in agricultural enterprises is an urgent matter. It is appropriate to utilize two methods of biohydrogen production: a thermochemical method – from crop-based biomass and anaerobic digestion (fermentation) method – from animal-based biomass.. It is appropriate to use gasifiers for the thermochemical method and biore-actors for fermentation method. The theoretical potential of biohydrogen was established with due regard to the amount of biomass which is necessary for utilization in livestock agriculture, for fields fertilization as well as with the consideration of the coefficients of concordance with hydrogen equivalent and loss factor under biohydrogen production. The theoretical potential of biohydrogen from crop-based biomass in Ukraine amounts to 77 billion m ³ , during the period of three years (on average 25.6 billion m ³ per year).