Scientific justification of energy policy priorities is impossible without using corresponding analytical instruments, i.e. mathematical models. Exactness of the estimates depends, among other factors, on the correct choice of methodological approach to the research objectives and available information about the object of modeling. Analyzing the international experience of developing and use of applied systems of energy systems, the author formulates conclusions as regards practical advisability of the development of a model of Ukraine's energy system and acceptable methodological and organizational approach for the completion of the above mentioned task.

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The author is analyzing the nature and dependence of the current dynamics of energy supply, as well as basic conditions for its formation and possible directions of its development. In this scope, he shows imperfection of the approach for combination of market factors and state regulation that determine the character of coal products and natural gas supply

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The article investigates the character and conditionality of the existing practice of price formation in the international trade in natural gas. In particular, it has been established that one of important consequences of the consecutive realization of the policy of the liberalization of natural gas markets in the European countries, became decoupling between the price and principles of gas price formation. That caused a transition from the previously predominant pricing formula in the international contracts ("netbackprice") to the one based on competition principles ("gas-alternative fuel").
In European countries, they mention three basic approaches to defining the gas price in long term contracts. The first one consists in linking the gas price to the price of a basket of alternative energy resources (coal and oil products, which are traded on the stock market and have a "market price"). The other one is based on the price for monthly futures contracts for an indicative oil type (as a rule, it is Brent). And the price level on the spot market is the third reference indicator for the formation of gas price.
In parallel with the existing system of contract relations on the European gas market, in recent years, a principally new market model has been shaping whose characteristic features are a stock market based pricing formation and complete refusal from long term contracts in favor of spot transactions. The elements of the new system have been united into the EU GasTargetModel. It is planned that this model include all EU Member Countries and those of the Energy Community, whose member is Ukraine.
It is established that the contract for the sale of natural gas in 2009-2019 between National Joint-Stock Company Naftogas Ukrainy and Open Joint-Stock Company Gazprom of 19.01.2009 is a typical "take or pay" contract of Groningen type with a linking to oil product price and similar to those used by the Russian monopolist in gas trade in long term contracts with absolute majority of European countries. For Ukraine, that contract allowed a transparent and forecastable calculation of the gas price, and, while the economic justification of the basic price of 450USD per 1000 cubic meters remains disputable, it became an effective incentive to real fuel economy in our country.
The authors justify that the losses incurred due to the conclusion of the gas contract of 19.01.2009 were caused exclusively by the market factors and are similar, in their nature and volumes, to those incurred as a result of lowering prices for and reduction of the world demand for metal items, and the further steps towards its lowering, in reality, not so improved the competitiveness of Ukraine's produce on the world markets, as recovered the previous profitability level profitability of certain activities.
Besides, the high prices for the imported natural gas led to the emergence of private suppliers, in particular, Ostchem HoldingLimited, which, in 2013, supplied almost half of natural gas from abroad. At the same time, the terms of the contracts with Ostchem HoldingLimited are incomparable, in financial and commercial way, to those with Naftogas Ukrainy, which may become a precondition for the appearance of a new private vertically integrated monopoly in place of the existing state owned company.

Keywords: natural gas transfer price formation, European gas market, Ukraine's gas market, liberalization, long-term gas contracts, spot prices

Paper focuses on the present condition of the biofuels market in Ukraine, Ukraine's international obligations regarding energy consumption from renewables by 2020 and possibilities to achieve the set goal. Theoretically, reaching the set goal is possible, but in practice the goal of 10% renewables in the transport sector by 2020 will probably be unachievable. The structure of energy consumption in 2020 is expected to be significantly different from that presumed by the National Action Plan on Renewables until 2020, and less biofuels would be needed to achieve the goal of 10% renewables in transport sector by 2020 than it is set out by the mentioned Action Plan. While maintaining the structure of fuel consumption by road subsector of 2015, in order to provide 10% of energy from re-newables in the automotive sub-sector, about 164 thousand toe bioethanol and 256 thousand tons toe of biodiesel are needed. The abolishment of the mandatory blending of 5% of biofuels was inappropriate, as without this requirement market growth ceased. The measures to enhance biofuels market include reducing the excise duty rate for bioethanol compared with a rate of excise duty on petrol; adopting sustainability criteria of biofuels; expansion of types of biofuels; information campaigns to popularize biofuels; reducing the cost of parking for cars, marked for the use of large volumes of biofuels in municipal parking lots; permit for vehicles marked for the use of large amounts of biofuel to use the lanes for public transport; encouraging the market to sell biofuels with high content of biological components; providing financial preferences for sellers of petroleum products in order to create the infrastructure for blending of biological component of fuel.
The article was prepared within the research project on “Economic policy of the development of integrated energy markets of Ukraine”.

Keywords: biofuel, bioethanol, biodiesel, international obligations, state regulation

The paper focuses on the potential of biogas use in Ukraine. Regulatory policy options for biogas projects were considered, and economic assessment and assessment of biogas projects' environmental impact were made. The results show that the implementation of biogas projects in Ukraine leads to positive macroeconomic effects beginning in 2018-2019. In 2025-2029, additional GDP growth could reach 0.3%. Despite the fact that domestic consumers do not directly participate in investment processes, in the medium and long-run, all groups of households will have positive impact on the level of real income. Wide-scale implementation of biogas projects in Ukraine would lead to moderate structural changes, mainly causing a slowdown in coal output and use, natural gas mining, and steam and hot water supply. The greatest slowdown would be observed in case of coal whose demand is reduced due to the replacement by solid and gaseous biofuels. The use of biogas instead of burning fossil fuels would save 11.462-19.066 million tons of CO2eq.
In order for biogas projects to become available for medium-sized businesses in Ukraine, governmental internal and external loan guarantees should be introduced; lower interest rates on loans through the cooperation of Ukrainian banks with international and domestic financial institutions should be implemented. The cost of capital needs to be reduced; dissemination of information on the benefits of biogas projects, the priority connection to the grid for electricity producers from biogas, the modernization of electricity grids and infrastructure are needed. And in the long term, compulsory use of biogas should be introduced for agro-industrial companies whose activities are related to the formation of wastes.

Keywords: biogas, CO2 emissions, modelling, regulatory policy

Compliance to the principles of free access to gas networks on a market basis, objectivity reflection of the system's cost, transparency and predictability of market participants requires changes to the tariff setting rules for transportation services. The introduction of the "entry-exit" tariff model is intended to ensure the achieve-ment of new market requirements and the establishment of common European rules for conducting economic activities. Changing the internal model of gas trans-portation also results in a change in the pricing principles for services provided by the TSO. Henceforth, the charge for transportation services should be taken not for the transport distance, but for the capacity of the entrance and exit points which should be sold publicly and independently. It allows for a more objective consider-ation of the operating costs of servicing the system and providing greater commer-cial variability in ordering system services by business entities.
However, European legislation does not define a single standard for the "entry-exit" model. Depending on the technical features of the network and the priorities of the national policy, each country determines the best option for itself. In this paper we used a set of mathematical models to evaluate the implications of the in-troduction of three alternative variants of the tariff model in two variants of work-load GTS (optimistic and pessimistic scenarios): full "entry-exit" model, two market zones, and "entry-exit" model with a long-term reservation. The results of the calculations were compared with the baselane scenario, which does not involve a change in the market model and gas transit is carried out in accordance with the terms of long-term contracts of 2009.
In general, changing the model for providing transport services in the gas market should lead to fundamental institutional transformations of contractual relations between all market actors and the principles of market functioning.

Keywords: natural gas market, transport operator, 'entry-exit' model, long-term transit contracts