METHODS OF REDUCTION OF CO 2 EMISSIONS AT GAS COMPRESSOR STATIONS UTILIZING COGENERATION TECHNOLOGIES

Transcription

1 METHODS OF REDUCTION OF CO 2 EMISSIONS AT GAS COMPRESSOR STATIONS UTILIZING COGENERATION TECHNOLOGIES Grygoriy BABIYEV, PhD. of Engineering, UKRTRANSGAS Affiliated Company, Ukraine 1. MANKIND AND ENVIRONMENT Mankind is regulating more and more its interaction with environment. Influencing the environment, mankind causes negative changes to it. Mankind is a considerable part of our environment and this part increases. Thus, influencing negatively the environment, mankind negatively influences itself. To conclude, mankind has to regulate its interaction with the environment actively. One of the essential aspects of such regulation is reduction of CO 2 and other greenhouse gases emissions. This is provided in the most important documents within the UN framework. 2. THE MAIN GUIDELINES FOR THE REDUCTION OF GREENHOUSE GASES EMISSIONS IN UKRAINE To reduce emissions of greenhouse gases Ukraine has to do the following: substitute high-molecular hydrocarbon fuels with low-molecular ones involve wind, solar, hydro and geothermal energy into the energetic balance of the country widely apply biomass for its further combustion and production of liquid and gaseous fuels apply energy efficient technologies and equipment increase energy efficiency of technological processes Over the last years Ukraine consumes about 75x10 9 m³ of natural gas a year, or about 40% of the country s fuel. Ukraine has a possibility to involve in its annual fuel balance 15x10 6 m 3 of biomass, what will reduce CO 2 emissions by 15x10 9 m 3 respectively. It is possible to substitute coal or oil combustion with 10x10 9 m 3 of biogas what will considerably reduce the CO 2 emissions. Ukraine is able to regulate natural gas application increasing the efficiency of its consumption. Such measures allowed to reduce natural gas consumption in Ukraine in by 11x10 9 m 3 a year what resulted in adequate reduction of CO 2 emissions by 11x10 9 m 3 a year. Ukrtransgas, the company, I am representing, holds an active position on these issues. We work on reduction of greenhouse gases with the following methods: increase of the efficiency of compressor stations engines, optimization of gas flows to reduce fuel gas consumption at all compressor stations, installation of cogeneration and trigeneration technologies on compressor stations increasing the efficiency of fuel usage, usage of turbo-expander plants for electricity production. Increase of the efficiency rates of gas engines and optimization of gas flows leads to 25-30% decrease in gas consumption and respective decrease of CO 2 emissions. Application of polygeneration at compressor stations and turbo-expander technologies allows to produce heat and power using the waste energy potential of gas transmission system. It allows to reduce CO 2 emissions in Ukraine by 5x10 9 m 3 a year. 3. APPLICATION OF COGENERATION TECHNOLOGIES AT GAS TRANSPORTATION SYSTEM Expansion of gas transportation networks dramatically actualizes the issues of optimization of energy resources and reduction of negative environmental impact through pipeline construction. At present the efficiency rate of engines at gas compressor stations is lower than 40%, and the efficiency rate of the future engines will not exceed 50%. Therefore, more than 50% of fuel gas combustion products come to the environment. These constitute energy losses, and as such they should be reduced.

2 Similar problems attract attention of pipeline industry engineers in many countries. And the main part of technical solutions to increase efficiency rate of gas turbines are based on cogeneration technologies aimed to produce additional quantities of heat and power. These technologies allow to save natural gas at power stations, and therefore to reduce СО 2 emissions to the atmosphere. The first implementation of cogeneration technologies in Ukraine is projected at Bogorodchany compressor station, Prykarpattransgas. The project calls for annual generation of 540x10 6 kwh of electricity and up to 419x10 12 Joules of heat. Ukrtransgas estimates the volume of investments required for the project at US $36x10 6. The project s construction period is 2 years. The costs of generation of 1 kwh of electricity at cogeneration facility are projected at US $ The project s payback period is 4 years after putting the facility into operation. Similar projects can be implemented at more than 40 compressor stations of Ukraine s gas transmission system, which will result in total installed capacity of some 2x10 9 W. Average implementation cost per 1 kw of installed electric capacity equals to US $500. Implementation of cogeneration technologies on all Ukrainian compressor stations with gas driven turbines allows the production of approximately (15-16)x10 9 kwh of electricity per annum, corresponding up to US $( ) x10 6. This will reduce the amount of natural gas used at thermal power plants in Ukraine by ( )x10 9 m 3 to produce the corresponding amount of electricity, and will result in decrease by ( )x10 9 m 3 of СО 2 emissions into the atmosphere (corresponding to 9.8x10 6 ton of СО 2 ). With an estimated increase by year 2020 of annual natural gas consumption in Europe by additional ( )x10 9 m 3, implementation of cogeneration facilities at existing gas transmission systems will allow to: move gas in new pipelines with electric-driven compressors powered by cogeneration plants mounted at compressor stations of the existing pipelines, supply heat from cogeneration plants to the infrastructure of existing and new pipelines. This leads to savings on costs of fuel gas used for heat production and costs of boiler houses construction, transport 150 x10 9 m 3 of gas from its production areas to Europe without utilization of 30 x x10 9 m 3 of fuel gas, reduce exhausts emissions into the atmosphere up to 300x10 9 m 3 annually by increase of annual gas transportation volumes by 150x10 9 m 3. The temperature of these emissions is about 500 о С, they consist of 30x10 9 m 3 СО 2 (or 59x10 6 ton СО 2 respectively), reduce capital outlays by 10-15% and operating costs by 30 %. 4. NEW PRINCIPAL SOLUTIONS IN PIPELINES CONSTRUCTION Utilization of cogeneration technologies allows to propose a number of new principal solutions in pipeline construction Branchless Transmission from Production Area to Consumption Area Applicable for the scheme of gas pipeline from gas production area to gas consumption area without branch pipelines to other areas (Scheme 1). In this case CHP facility and gas driven compressor stations (CS) should be built in gas production area. The capacity of CHP s electric generators should be sufficient to transport gas through electric driven CS as well as to supply power to other potential consumers, and account for losses in electricity transmission networks. CHP s steam turbine uses steam from two boilers a boiler utilizing exhaust heat from CS gas turbines, and a CHP boiler. Along the pipeline route there should be CS with electric driven force pumps. In gas consumption area, i.e. in the end point of gas pipeline, there should be an underground gas storage facility (UGS). Its take-off volumes should be sufficient for consumers supply for the period of eventual breakdown of power system supplying electric drives. If this period is short, a pipe header can be used instead of UGS construction. The use of gas driven CS is closely connected with safety issues of gas transportation, i.e. gas pipeline has its independent energy source natural gas. This scheme does not envisage gas driven compressors. This scheme is advantageous for companies striving to be players on both electricity and gas markets. The calculation of economic effectiveness is represented in Table 1.

3 Production Area Driven Compressor Station with CHP Unit Pipeline Electric Driven Compressor Stations Eventual Break in Pipeline Pipeline Consumption Area Scheme 1. Pipelines with Electric Driven Compressor Stations Supplied by CHP Unit

4 Initial Data 1.Pipeline Length - 1,000 km 2.Number of CS - 10 units 3.Annual Pipeline Capacity - 25x10 9 m 3 4. price US $100 per 1,000 m 3 5.Cost per unit of fuel gas for gas turbine engines 3.75x10 6 m 3 a year 6.Cost of construction of gas turbine compressor station US $0.05x Cost of construction of electric driven compressor station with US $0.04x10 9 Traditional Scheme for Turbine 1.Number of compressors at one station 7x10x x10 6 W 2.Number of compressors in operation - 5 units 3.Annual gas consumption at all compressor stations 1.85x10 9 m 3 4.Cost of used fuel gas - US $187.5 x Cost of construction of compressor stations US $0.5x10 9 Scheme for Turbine, CHP and Electric Drive 1.Number of compressors at one station 6x10 x10 6 W 2.Compressors in operation 5 units 3.Annual cost of fuel gas for gas turbine and CHP unit 1.145x10 9 m 3 4.Cost of used fuel gas US $114.5x Cost of construction of all compressor stations and CHP unit US $0.687x Additional profit from reduction of operating costs and CO 2 emissions within 20 years US $1.96x10 9 Table1: Economic Efficiency of Pipeline Construction for Different Schemes of CS Equipment and Energy Supply The main advantages of this approach are: considerable energy saving, considerable operating costs reduction, considerable reduction of СО 2 emissions and, as a result, reduction of payment for emissions, simplification of pipeline maintenance and management structures as well as local service lines scheme Approximation to Settlements or Other Heat Consumers Applicable for construction of a pipeline with compressor stations located close to residential areas or other heat consumers (Scheme 2). In this case the pipeline can have complex configuration, and pipeline linear part can be longer than optimal. This option includes location of CS close to heat consumption areas. CS should be driven by gas turbines with heat recovering boilers. Although the pipeline length increases 1.5 times comparing to the optimal length, there is no need to build branch pipelines as well as separate gas metering and gas distribution stations to such facilities. The economic indicators of this approach (Table 2) prove its effectiveness for new pipeline construction, even with double the optimal length. Initial data for compared pipeline variants Traditional gas pipeline: length 1,000 km, number of CS 10 units 1 pipeline located close to heat consumers: length 1,500 km, number of CS 15 units. Cost increase compared to traditional solution: pipeline construction - US$ 0.85x10 9, annual operating costs US $0.0625x10 9 The main profitability indicators of a pipeline located close to heat consumers: 2 - annual heat sales US $0.175x annual earnings from reduction of CO 2 emissions US$ 0.01x Annual operating profit of a gas pipeline located close to heat consumers US $0.1225x Additional investment return period 7 years Table 2: Economic Efficiency of Pipeline Construction with CS Located Close to Heat Consumers

5 Production Area Compressor Stations with Turbines and Heat Utilizers Consumption Area Consumption Area Eventual Break in Pipeline Compressor Stations with Turbines and Heat Utilizers Consumption Area Consumption Area Scheme 2. Pipeline with Compressor Stations Located Close to Heat Consumers

6 4.3. Construction of new Routes Consisting of Several Parallel Pipelines In this case (Scheme 3) gas driven CS with cogeneration facilities are projected at one pipeline, CS with electric drives are projected at another pipeline. The amount of generated electricity at the pipeline with cogeneration facilities should be sufficient to transport additional 40% of natural gas volumes through the pipeline with electric driven CS. Throughput capacity of pipelines should be calculated considering this factor. This scheme can be also applicable when cogeneration facilities are built at gas driven CS of the existing pipeline and a new pipeline with electric driven CS is built in the route of the existing pipeline. According to technical and economic analysis of the above approaches, construction of cogeneration facilities at the existing and new gas pipelines is feasible. 5. FEASIBILITY OF APPLICATION OF COGENERATION TECHNOLOGIES AT GAS TRANSPORTATION SYSTEMS Cogeneration facilities at gas pipelines allow to organize pipeline construction according to new solutions. Implementation of cogeneration facilities while transporting gas from Russia to Europe allows to reduce fuel gas consumption by up to 30x10 9 m 3 a year and will respectively reduce the СО 2 emissions. International organizations dealing with environment, energy, gas, energy efficiency issues, could examine the possibilities of implementation of cogeneration facilities at gas transport and recommend them for preferable or essential use in projected new pipelines and modernization of the existing pipelines. Volumes of natural gas transported in the world exceed 2x10 12 m 3. Application of cogeneration technologies could reduce gas volumes at compressor stations approximately at 50x10 9 m 3 and reduce the CO 2 emissions respectively.

7 Production Area Pipeline with Electric Driven CS Pipeline with Driven CS and Cogeneration Facilities Consumption Area Scheme 3. Construction of New Parallel Pipelines and Cogeneration Facilities