JOINT ELECTRICITY AND HEAT PRODUCTION POSSIBILITIES ON THE BASIS OF THE DISTRICT TRIGENERATION PLANT

Renewable energy has become increasingly important in the last decade due to the limited reserves of fossil fuels and environmental issues related to CO2 emissions. The paper investigates the joint production possibility of electricity and heat in the Tomsk district Stepanovka, using modern trigeneration plant. The analysis was performed based on a comparison of the two alternatives for the area: the use of a diesel power plant (DPP) or gas-piston units (GPU) on biofuel. Technical and economic indicators for two different systems were calculated to evaluate the projects effectiveness.


Introduction
Reduction of natural hydrocarbon resources, rise in price of oil and gas production systems, electric and heat energy tariffs increase, environment pollution by emission of carbon dioxide and global warming [1,2] enhance the interest in the use of renewable energy sources.Personal power plants, operating on renewable energy, can become an alternative to traditional diesel power plants, operating on imported and expensive fuel, for rural areas of Tomsk region.
Energy resources consumption reduction and their efficient allocation can be provided by more efficient power plant with a combined production of heat / electricity / cold.[1] The heat excess generated in the motor can be used for heat and cold generation for consumer needs.Usually, heat demand is dramatically reduced in summer, due to heating and ventilation necessity deficiency.However it's possible to dispose of the large volumes heat by means of cold power generation for manufacture process needs.This is possible by including compressor or absorption conditioners in the heat network diagram.This allows to increase the plant efficiency in summer time.[1,2,3] The current state of the Stepanovka district communal infrastructure is characterized by a high grade of equipment deterioration; deterioration rate ranges from 48 % to 82 % for most objects.On the average, 68 % of utilities have served set time-limit.This results in excessive networks losses, the low equipment efficiency factor, excessive accident risk.This requires a higher cost of operation and maintenance of municipal infrastructure.Special attention should be given to following utilities problems: • high level of fixed assets depreciation; • engineering systems low reliability, especially electric power supply systems; • insufficient replacement scale of electrical networks and modernization of boiler stations and DES equipment; • insufficient network replacement scale and retrofitting.
According to the project the electrical energy production is planned to be covered by the diesel power plant and the biomass gas piston installation, the electric and heating systems will be reconstructed.Wastes from agriculture and timber industry may be used as a biofuel source.The exhaust steam will be provided for socially important facilities heating such as kindergarten, school, hospital and others to enhance efficiency.
The article deals with three major project aspects: • required heat and electricity loads analysis and assessment; • the technical and economic viability analysis; • environmental impact assessment.

The district energy consumption volume assessment
It is necessary to evaluate the heat and electric power consumption volumes for power supply system optimization.The utilities consumption standard values for the hot water supply in premises are shown in the Table 1.
Table 1.Consumption standard values for the hot water supply. No.

The premises accomplishment rate
The utilities consumption ratio (m 3 per month for 1 person)

Environment emissions reduction
Annual gross atmosphere emissions were calculated for the operating diesel installations according to the technique [2].As basic data we used: • data from technical manufacturer documentation of diesel installation operational power for calculation of the maximum onetime emissions; • calculations result of standard values of diesel engine annual fuel consumption for the evaluation of gross emissions in the atmosphere.
The average specific values of emissions indicators which were given in the technique [2] reflect the main toxicity parameters change regularities of diesels depending on a load and high-speed operating mode of the power plant, and also power and tip speed ratio of the diesel engine [2], [3].Also, working process organization features of multi-cylinder powerful diesel installations are taken into account.
Emissions calculations are performed for the following harmful substances coming to the atmosphere with the exhaust gases of the diesel installations: • carbon oxide (CO); • nitrogen oxides (NOx) (in terms of NO2); • hydrocarbons (CH)).

Table 2 .
The utilities consumption ratio values for heating in residential and non-residential premises of the Tomsk region during the heating season.The fuel economy of the combined energy development is distributed in proportion to (types of the developed energy) relative shares: EST BGВ-total consumption of mini-CHPP biogas for power supply; BG C -biogas costs, related to one ton of equivalent fuel; ¦ -Money inflow during n mini-CHPP maintenance years, rub.