Biomethane is one of the most promising renewable gases (hereafter – RG) – a flexible and easily storable fuel, and, when used along with the natural gas in any mixing proportion, no adjustments on equipment designed to use natural gas are required. In regions where natural gas grids already exist, there is a system suitable for distribution of the biomethane as well. Moreover, improving energy efficiency and sustainability of the gas infrastructure, it can be used as total substitute for natural gas. Since it has the same chemical properties as natural gas, with methane content level greater than 96 %, biomethane is suitable both for heat and electricity generation, and the use in transport.Biomethane is injected into the natural gas networks of many Member States of the European Union (hereafter – the EU) on a regular basis for more than a decade, with the Netherlands, Germany, Austria, Sweden and France being among pioneers in this field. In most early cases, permission to inject biomethane into the natural gas grids came as part of a policy to decarbonize the road transport sector and was granted on a case-by-case basis. The intention to legally frame and standardise the EU’s biomethane injection into the natural gas networks came much later and was fulfilled in the second half of the present decade.This paper addresses the biomethane injection into the natural gas grids in some EU countries, highlights a few crucial aspects in this process, including but not limited to trends in standardisation and legal framework, injection conditions and pressure levels, as well as centralised biogas feedstock collection points and the biomethane injection facilities. In a wider context, the paper deals with the role of biomethane in the EU energy transition and further use of the existing natural gas networks.

Currently, problems related to the operation and exploitation of safe gas distribution networks are deepening in Latvia and Eastern Europe, as the number of outworn underground gas pipelines is steadily increasing. It should be noted that there is a rather wide choice of technology and materials for gas distribution pipeline reconstruction, while at the same time there is no universal method that equally meets all possible work requirements. Therefore, it is an urgent task to understand the operational algorithm, while choosing optimal reconstruction option, classifying and determining the criteria affecting the choice, and determining the scope of each reconstruction method. For this reason, it is necessary to develop a scientifically based methodology for selecting the optimal method for the reconstruction of outworn gas distribution pipelines. Therefore, there are the following tasks that need to be accomplished: to carry out a complex analysis of reconstruction methods and factors determining the choice of an optimal gas distribution pipeline reconstruction method as well as perform the analysis of current state and development of gas supply network; to develop an algorithm for selecting an optimal gas distribution pipeline reconstruction method based on a multi-criteria approach; to develop a mathematical model for the selection of an optimal reconstruction method and scientifically based complex evaluation procedures taking into account technical and economic criteria; to analyse the interaction of the polyethylene gas pipeline with the steel frame during the post-reconstruction process using U-shaped pipe; to develop recommendations for the optimisation of gas distribution network reconstruction programmes. As a result of these tasks, a scientifically justified methodology for the selection of an optimal method for the reconstruction of the gas distribution pipes has been developed.

The aim of the research is to create the ecological heat insulation material out of coniferous tree greenery (needles and thin branches). Following the three factor experiment plan, samples were made and tested in a laboratory for their thermal conductivity and density. The findings show that the elaborated needle heat insulation material is equal to existing insulation materials from wood and it is worth to continue this research for further product development and manufacturing.

In the early 2010s, only 23 countries had access to the liquefied natural gas (hereinafter – LNG). Import terminals, despite attractive short-term economics, took long time to build, and rigid supply contracts made truly global use of LNG rather complicated. Concerns about geo-political risks also stunted demand growth from existing supply sources, even when new LNG export routes and sources became available. Current natural gas market is very different, both in terms of market participants and accessibility and diversity of services. In 2019, the number of LNG importing countries reached 43. Rising competition among suppliers and increasing liquidity of markets themselves created favourable conditions to diversify contract duration, size, and flexibility. In addition, development of floating storage and regasification unit (hereinafter – FSRU) technology provided LNG suppliers with a quick response option to sudden demand fluctuations in regional and local natural gas markets [1]. Moreover, LNG is one of the major options not only for bringing the natural gas to regions where its pipeline supply infrastructure is historically absent, limited or underdeveloped, but also for diversification of the natural gas supply routes and sources in regions with sufficient state of pipeline delivery possibilities. And it concerns smaller natural gas markets, like the Baltic States and Finland as well. Accordingly, prospects for use of LNG there in both mid and long-term perspective must be carefully evaluated, especially in regards to emerging bunkering business in the Baltic Sea aquatory and energy transition in Finland, replacing coal base-load generation with other, more sustainable and environmentally friendly alternatives.

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