Technologies for Distributed Generation: key performance factors for industrial application

INTRODUCTION

Today, the key characteristic of the develop­ment of the electric power industry is a significant cost reduction of distributed generation sources installations, including renewable energy sourc­es. Such sources allow decentralization of elec­tric production and the large-scale development of distributed sources around the world [Trachuk A. V., Linder N.V. and others, 2017]. This sig­nificantly changes characteristics of electricity consumption, as well as and consumer behavior patterns in electricity market. Consumption is becoming more flexible and mobile. Consum­ers of electricity can in the same time become its suppliers, which requires, in turn, revision of the norms of the current system of electrici­ty market regulation (EnergyDemocracy) [Faria P., Vale Z., 2011; Volkova TO., Salnikova E.A., Shuvalova D.G., 2011; Trachuk A. V., Linder N. V., 2017]. Generating capacities of different cat­egories have their advantages and disadvantages in certain economic conditions. In this study, the goal is:

• to analyze trends in the development of small (distributed) generation; to define the main categories of objects of small and me­dium generation,
• which belong not to electric companies, but to consumers;
• to study the effects of distributed generation projects;
• to estimate the effect of large-scale application of distribut­ed generation for the country in general and recommend a number of measures and actions for development of indus­trial distributed generation in Russia.

TECHNOLOGIES AND EFFICIENCY OF DISTRIBUTED GENERATION

The literature often contrasts the own generation of consumer companies and centralized power supply [Hansen c. J., Bower J., 2004; A. A., HawkesA., 2004; Trachuk A. V., 2010a], Capacities of different categories in certain economic conditions have their advantages and disadvantages. In most studies, distributed gen­eration is understood as generation of electricity by a lot of local consumers that produce heat and electric energy for own needs and direct the surplus to the energy system through a common network infrastructure [Sellyakhova O., 2012; Trachuk AV, 2010 b]. The basic definitions of distributed generation in world prac­tice are given in Table. 1.

Distributed generation technologies. Distributed genera­tion technologies, as usual, are designed for low-power plants (up to 25 MW), including renewable electricity sources (RES). The most complete classification of distributed generation technolo­gies is provided in [Stennikova VA, Voropai NI, 2014] (Tig. 1).

Analysis shows that most of the technologies that are used for distributed generation plants are based on direct burning of solid fuel (coal, biomass and solid household waste). Combustion of natural gas is used in gas turbine plants, gas piston units, com- bined-cycle and other installations. Wind power stations, small hydroelectric power stations, solar power plants and photovoltaic installations, solar heating stations, as well as hybrid plants use relevant renewable energy sources. Heat pumps use low-poten­tial heat both for heat supply and for cold supply. Nuclear power plants of low power as autonomous sources of electric and ther­mal energy are used in isolated energy areas.

Fuel cells including gas piston aggregates, microturbines, Stirling engines, energy storage devices (chemical, inertial, grav­itational and others), rotor-blade engines, chillers (devices for air cooling) are promising.

The main sources of distributed generation have different technical characteristics (Table 2) and different economic effi­ciency as technological directions, as follows:

• gas powered engines (gas turbine installations, microtur­bines, low-power combined-cycle plants, gas piston inter­nal combustion engines) are of high quality and ensure the efficiency of energy supply;
• rotary-lobe engines of external combustion with other types of fuel, as well as technologies for obtaining gas fuel at the place of electricity production, provide a reduction in fuel risks and costs relative to tariffed types of electricity;
• small cogeneration plants make it possible to increase the efficiency of fuel use up to 80-90 percent;
• fuel cells of a new generation (in particular, such field of development as hydrogen energy) are effective in supplying isolated territories and mobile consumers.

Distributed generation is most often used:

• as autonomous sources of electricity, heat (in cogeneration mode) and cold (in tri-generation mode);
• to remove peak loads in parallel operation modes with the centralized power supply system;
• in cogeneration and trigeneration projects based on the use of alternative fuels: biogas, associated petroleum gas, coal mine methane and other types; [1] in projects with specific requirements for energy quality, re­liability, start-up times, ecology, which under specific con­ditions cannot be provided by centralized power systems [McDonald, 2005; Trachuk, 2011 a].

Autonomous sources. Distributed generation on the ba­sis of autonomous sources is used by industrial enterprises, of­fice centers, and social infrastructure facilities if the centralized technological connection is not available for some reason. Such reasons include, in particular: territorial remoteness of facilities, a shortage of installed capacity in the region, limited bandwidth of the network infrastructure. In addition, centralized power sup­ply can be economically inefficient (high connection price, high tariffs, other reasons) or may not meet the requirements of the consumer by the terms of connection taking into account recon­struction and development plans for networks and generation. This is why new or reconstructed medium and small enterprises of various industries increasingly choose distributed generation as an alternative to joining the country's energy systems.

Distributed systems, including those integrated in a local area network, can be used to supply energy to complex built-up mi­cro-district and even cities built under the national program "Af­fordable and Comfortable Housing" [Energy Efficient Megapolis - Smart city "Novaja Moskva", 2015]. Such construction can be planned in the territories not provided with the corresponding infrastructure. Distributed generation allows the introduction of power capacity in stages, as electricity consumption increases, for example, for mechanization of construction work or in ac­cordance with the order of commissioning of residential and in­frastructural facilities [Decentralised generation, 2002].

Parallel operation with the power system. If the production volume is changed or the facility is redesigned, especially with an uneven daily energy consumption profile, both a deficit and a sur­plus of electricity supplies from the central power system are pos­sible. During peak loads, a distributed system can transmit excess power when connected to a central power system. And vice versa, it may be economically efficient to design the capacities of dis­tributed systems, based on the amount of constant consumption, while the peak loads are covered by the central power system.

Cogeneration and trigeneration. Cogeneration is a process of joint generation of electricity and heat with the use of a single source of primary energy (nthe case of trigeneration, the production of cold is added). Cogeneration is the most effective solution for reconstruc­tion of boiler houses that are switching to gas or re-profiling into mini-CHP. Cogeneration and trigeneration is one of the most eco­nomical solutions for office buildings, shopping malls, sports facil­ities power supply [AckermannT., Anderson G., Soeder L., 2001].

When implementing these technologies, alternative fuels can be used. As a rule, they are used to solve a complex problem: im­prove the environmental situation and meet the company's own needs for heat and electricity. For example, associated petroleum gas - with the arrangement of new oil fields, mine methane - with the creation of effective systems of explosion safety, biogas - with the improvement of the ecological situation in the areas of urban landfills and treatment facilities.

Specialized solutions. Specialized solutions for design of distributed generation systems can be applied depending on the industry and territory features where the enterprise is located. Thus, in of greenhouse energy supply, carbon dioxide released during generation can be used; livestock farms use biogas; Eco­nomical trieneration is effective in the energy supply of swim­ming pools and water parks.

The need to comply with strict environmental requirements for emissions of harmful substances, noise, vibrations at ski re­sorts and in hunting facilities leads to the usage in design of a distributed generation system for special equipment. The same applies to mobile power sources, power supply features of re­mote unattended power systems, such as radio relay stations on long-distance communication lines, pipelines chemical protec­tion systems, weather stations.

Technical solutions - microturbines and low-power tur­bines. For a long time, from the 60s to the 90s of the 20th cen­tury, large-scale construction of distributed power systems was restrained, in particular, because of the lack of an adequate tech­nological base. The practical realization of the concept of dis­tributed generation systems was facilitated by the commercial production of a completely new class of power equipment - mi­croturbines (15 kW - I MW) and radial turbines of low power (2 MW). Nowadays, some international companies have managed to establish a mass production of reliable, simple and relatively inexpensive gas small and microturbines [Massel A., Massel L., 2015]. The design of such generation is carried out in accordance with the specific requirements of specific consumers, power units are completed depending on the purposes, tasks and use cases, including for the production of heat and cooling. Compactness, compliance with environmental requirements, low noise and vi­bration level, technical possibility of an operational load change without a significant reduction in efficiency, high reliability, and also greater efficiency in cogeneration and trigeneration modes in comparison with equipment of other classes are the main advan­tages of small and microturbines [Hovalova T.V., 2017]. These and other characteristics have influenced the increase in the spread of small and medium generation in the world [European Smart Grid, 2006]. For example, in the EU countries, distributed generation makes about 10% of the total electricity production.

In the United States, about 12 million small distributed power plants are operated (the capacity of individual installations is up to 60 MW, the total installed capacity is over 220 G, increase is about 5 GW per year). Apart of the distributed generation objects is used as an emergency reserve (about 84 GW), the rest are used as the main source of electricity. The Distributed Power Coalition of America predicts that in the next two decades 20% of new generation capacity will be from distributed generation objects [Grid 2030, 2003].'

RESEARCH METHODOLOGY

Proceeding from all above, we have formulated a research question: "What effects from the introduction of distributed gen­eration have an impact on the activities of companies in various industries and how can they affect the Russian economy?"

The empirical analysis was conducted on the basis of 12 Rus­sian companies, which work in different sectors (industrial pro­duction, housing and communal services, retail trade, construc­tion, food industry) and each of them uses its own generation.

RESEARCH RESULTS: EFFECTS OF INTRO­DUCING DISTRIBUTED GENERATION

The initial data for the study are given in Table. 3.

Effects of using distributed generation for enterprises.

Using the analysis of the data presented, a number of effects of the introduction of distributed generation for enterprises of various industries have been drawn up. The study did not attempt to assess the impact of large-scale introduction of distributed generation on the electricity (capacity) market. The revealed ef­fects can be generalized and divided into two large groups.

The technological effects include:

• Increasing the reliability of energy supply to consumers (in case when distributed generation is connected to a central­ized power supply, than in emergency situations such sys­tem maintains reliability of power supply, reduces or pre­vents damage);
• energy security through introduction of fuel free technolo­gies and expansion of the range of fuels, involvement of lo­cal energy resources, reduction of dependence on imported fuels;
• optimization of load management and creation of necessary technological reserves taking into account the production cycles of a particular enterprise;
• providing the technological component of the flexibility function of smart networks (in terms of generation);
• reducing the load on the environment, including CO emis­sions (especially reducing carbon dioxide and other pollut­ants (CO, SO ...) emissions into the atmosphere, in particu­lar for the sanatorium and resort industry in general and the oil and gas industry when flaring associated petroleum gas is burned).

Economic and social effects include:

• energy efficiency due to the following factors: optimization of the load graph, reduction of technological losses in the process of energy distribution, (the location of distributed generation facilities in the territorial proximity to the con­sumer makes it possible to dispense with the construction of regional power stations and the reconstruction or construc­tion of a network infrastructure;
• for owners of distributed generation, the cost of energy is usually lower than the regulated electricity tariffs for en­terprises, the operating costs of the units are stable and well-predicted, which allows for long-term production planning; the connection to the centralized power supply system is carried out on the basis of calculations that take into account both the payment for technological connection and the assessment of the risks of reducing the reliability of the electric power supply);
• usage of cogeneration, combination of fuels (the overall ef­ficiency of a modem combined electric and thermal power plant is 85-90%, whereas with the traditional use of only a condensing power plant, more than half of the energy re­leased from the combustion of fuel is lost due to the remov­al of surplus heat into the environment;
• due to cogeneration, the efficiency of energy and heat pro­duction increases by 30%, which is especially attractive in cases when the enterprise has by-products that serve as fuel for generation; efficient and proven technologies of com­bined production of electric energy and heat energy can be used in objects of any scale);
• providing consumers with electricity of specified quality;
• reduction of technological losses in networks, correspond­ing to a decrease in the cost of electricity;
• optimization, in some cases, significant savings, electricity costs due to a number of factors (lack of payment for tech­nological connection, optimization of the fuel component, minimization of investments in the network infrastructure, application of innovative technologies, application of spe­cialized technological solutions for a particular enterprise; There is no electricity component in the electricity tariff, that is, the tariff load in terms of the investment programs of the grid complex on all consumers of the region is decreasing);
• increasing the availability of energy supply for consumers, including those located in isolated areas, outside the Unified Energy System of the country.

It should be noted that distributed generation projects can be economically feasible at any scale [Trachuk, 2011b], but at pres­ent generation of energy at distributed generation facilities that have the status of a participant in the wholesale market, is unprof­itable for consumers, because the current rules oblige to sell gen­erated electricity to the wholesale market, buying it for consump­tion, that is infrastructure services. As a result, the profitability of distributed generation objects is ensured in the isolated mode of operation. Distributed generation projects with electric power less than 25 MW are generally recognized as economically viable (taking into account regional differences).So, the development of distributed generation requires adjusting the regulatory environ­ment, which will be noted in the conclusions.

INFLUENCE OF TECHNOLOGICAL, ECONOMIC AND SOCIAL EFFECTS OFTHE DISTRIBUTED GENERATION USAGE ON THE ECONOMY OFTHE RUSSIAN FEDERATION

The effects of distributed generation for enterprises, identi­fied in the course of the study, can affect the economy of the country as a whole, both now and in the future. As the scale of distributed generation increases, the effects will also increase. Some of the effects are transmitted directly from the level of the enterprise, some occur on a national scale.

At the same time, the database for research does not allow quantifying all possible scale effects and risks of such influence, but allows us to point out certain trends that are presented below.

Thus, the country effects achieved as a result of the introduc­tion of distributed generation allow us to conclude that the reor­ganization of the Russian electric power industry as an organiza­tional and business system into a network of localized clusters of energy producers and consumers integrated in the Unified Energy System that can use a common infrastructure and maintain a reli­able electricity supply throughout the country. The basis of such a paradigm in the electric power industry is distributed generation. Of course, a corresponding change in the regulatory environment requires a preliminary quantitative and qualitative assessment of the cost and consequences of such a transformation.

PRACTICAL APPLICATION OFTHE RESEARCH RESULTS

Based on the research results, a number of measures can be recommended for the development of industrial distributed gen­eration in Russia.

In the medium term:

• development of a strategy for the development of distribut­ed generation in the Russian Federation, including taking into account the implementation of projects for combined generation of electric power and thermal energy.

In the short term:

• adjustment of the regulatory environment, in particular the rules according to which power stations connected to the grid with a capacity of 25 MW or more are obliged to sell electricity in the wholesale market, which hinders the devel­opment of distributed generation, an increase in the power level threshold of such stations;
• simplification of the procedure for obtaining permits for the implementation of distributed generation projects;
• creation of legislative conditions allowing the entry into force of contracts for the supply of natural gas and electric power before the facility is put into operation;
• carrying out information campaigns and developing moti­vation programs, raising the level of awareness of interested persons;
• ensuring the stability of the regulatory environment after its formation for the maintenance and development of dis­tributed generation, which will help reduce investment risks for individual projects and improve the stability of energy markets in general.