Cogeneration, CHP As a Future Power & Heat Contents… Introduction. What is Cogeneration (CHP) ? Why Cogeneration ? Cogeneration Principle. Cogeneration Technologies. Application of Cogeneration. Economics of Cogeneration. Usefulness of Cogeneration Technology. Policies. Summary. Introduction Yes……I, you, society, organization, state, nation and world need development. Not only development but a Sustainable development. Sustainable development benefits social, economic, technological, and environmental. Power (electricity) and Heat (i.e.CHP) plays a major role for development. Yes… Cogeneration, Combined Heat and Power (CHP) can fulfill it for long way. What is Cogeneration ? • Cogeneration = the simultaneous production of heat and power, with a view to the practical application of both products. • A way of local energy production. • Used instead of separate production of heat and electricity. • Heat is main product, electricity by-product or alternate. • Uses heat that is lost otherwise. • Way to use energy more efficiently. • Different area’s of application. • Different technologies. Why Cogeneration ? • Improve energy efficiency. • Reduce use of fossil fuel. • Reduce emission of CO2. Also, • Reduce cost of energy. • If heat fits demand, the cheapest way of electricity production. • Improve security of supply. • Use of organic waste as fuel. • Position on energy market. Why Cogeneration ? Conventional power generation, on average, is only 35% efficient. Up to 65% of the energy potential is released as waste heat. More recent combined cycle generation can improve this to 55%. In conventional electricity generation, further losses of around 5-10% are associated with the transmission and distribution of electricity. Through the utilization of the heat, the efficiency of cogeneration plant can reach 90% or more. Cogeneration therefore offers energy savings ranging between 15-40%. Separate production of Electricity & Heat Cogeneration Energy Efficiency (I) Energy Efficiency (II) Energy Efficiency (III) Cogeneration Principle • When steam or gas expands through a turbine, nearly 60 to 70% of the input energy escapes with the exhaust steam or gas. • This energy in the exhaust steam or gas is utilized for meeting the process heat requirements, the efficiency of utilization of the fuel increases. • Such an application, where the electrical power and process heat requirements are met from the fuel, is termed as “Cogeneration”. • Since, most of the industries need both heat and electrical energy, cogeneration can be a sensible investment for industries. • It is also known as ‘Combined Heat and Power (CHP)’ and ‘Total Energy System’. Classification of Cogeneration Systems • There are two main types of cogeneration concepts – Topping Cycle plants – Bottoming Cycle plants Topping Cycle • A topping cycle plant generates electricity or mechanical power first • The four types of topping cycle cogeneration systems are: 1) A gas turbine or diesel engine producing electrical or mechanical power followed by a heat recovery boiler to create steam to drive a secondary steam turbine. This is called a combined-cycle topping system. Topping Cycle 2) The second type of system burns fuel (any type) to produce high-pressure steam that then passes through a steam turbine to produce power with the exhaust provides low- pressure process steam. This is a steam-turbine topping system. 3) A third type employs hot water from an engine jacket cooling system flowing to a heat recovery boiler, where it is converted to process steam and hot water for space heating 4) The fourth type is a gas-turbine topping system. A natural gas turbine drives a generator. The exhaust gas goes to a heat recovery boiler that makes process steam and process heat. Bottoming Cycle A bottoming cycle plant generates heat first. These plants are much less common than topping cycle plants. These plants exist in heavy industries such as glass or metal manufacturing where very high temperature furnaces are used. The waste gases coming out of the furnace is utilized in a boiler to generate steam, which drives the turbine to produce electricity. Cogeneration Technologies Backpressure Technology. Extraction Condensing Technology. Gas Turbine Heat Recovery Boiler Technology. Combined Cycle Technology. Reciprocating Engine Technology. Micro-turbines. Fuel cells. Stirling engines. Microturbine • Nowadays there are microturbines as small as 25 kW. • In general, microturbines can generate anywhere from 25 kW to 200 kW of electricity. • Microturbines are small high-speed generator power plants that include the turbine, compressor, generator, all of which are on a single shaft. • As well as the power electronics to deliver the power to the grid. • Moving part, use air bearings and do not need lubricating oil. • They are primarily fuelled with natural gas, but they can also operate with diesel, gasoline or other • similar high-energy fossil fuels. Research is ongoing on using biogas. Microturbine Microturbine Fuel cells • Fuel cells convert the chemical energy of hydrogen and oxygen directly into electricity without combustion and mechanical work such as in turbines or engines. • In fuel cells, the fuel and oxidant (air) are continuously fed to the cell. • All fuel cells are based on the oxidation of hydrogen. • The hydrogen used as fuel can be derived from a variety of sources, including natural gas, propane, coal and renewable such as biomass, or, through electrolysis, wind and solar energy. • A typical single cell delivers up to 1 volt. In order to get sufficient power; a fuel cell stack is made of several single cells connected in series. Fuel cells Fuel cells Stirling engines • The Stirling engine is an external combustion device and therefore differs substantially from conventional combustion plant where the fuel burns inside the machine. • Heat is supplied to the Stirling engine by an external source, such as burning gas, and this makes a working fluid, e.g. helium, expand and cause one of the two pistons to move inside a cylinder. This is known as the working piston. • A second piston, known as a displacer, then transfers the gas to a cool zone where it is recompressed by the working piston. The displacer then transfers the compressed gas or air to the hot region and the cycle continues. • The Stirling engine has fewer moving parts than conventional engines, and no valves, tappets, fuel injectors or spark ignition systems. It is therefore quieter than normal engines Stirling engines Heat-to-Power Ratio • Most important technical parameter influencing the selection of the type of cogeneration system. • The heat-to-power ratio of a facility should match with the characteristics of the cogeneration system to be installed. • It is defined as the “ratio of thermal energy to electricity required by the energy consuming facility”. • It can be expressed in different units such as Btu/kWh, kcal/kWh, lb./hr/kW. Heat-to-Power Ratio Heat-to-power ratios and other parameters of cogeneration systems Cogeneration Heat-to- Power Overall System Power Output (as efficiency ratio percent of (percent (kWth/kWe) fuel input Back-pressure steam 4.0-14.3 14-28 84-92 turbine Extraction- 2.0-10 22-40 60-80 condensing steam turbine Gas turbine 1.3-2.0 24-35 70-85 Combined cycle 1.0-1.7 34-40 69-83 Reciprocating engine 1.1-2.5 33-53 75-85 Advantages & Disadvantages Advantages Disadvantages Steam •High overall efficiency; •High heat: power ratios; Turbines •Any type of fuel may be used; •High cost; •Heat to power ratios can be varied through flexible •Slow start-up. operation; •Ability to meet more than one site heat grade requirement; •Wide range of sizes available; •Long working life. Gas •High reliability which permits - long-term •Limited number of unit sizes within the Turbines •unattended operation; Output range; •High grade heat available; •Lower mechanical efficiency than •Constant high speed enabling - close frequency Reciprocating engines; •Control of electrical output; •If gas fired, requires high-pressure supply or in-house boosters; •High power:weight ratio; •High noise levels (of high frequency can •No cooling water required; be easily alternated); •Relatively low investment cost per kWe •Poor efficiency at low loading (but they •electrical output can operate continuously at low loads); •Wide fuel range capability (diesel, LPG, •Can operate on premium fuels but need to •naphtha, associated gas, landfill sewage); be clean of dry; •Multi fuel capability; •Low emissions. Advantages & Disadvantages Advantages Disadvantages Reciprocati •High power efficiency, achievable over a wide load •Must be cooled, even if the ng Engines range; heat recovered is not reusable; •Relatively low investment cost per kWe •Low power:weight ratio and electrical output; out-of balance •Wide range of unit sizes from 3 kWe (there are •Forces requiring substantial 2,000 3 kWe installations in Germany) upward; foundations; •Part-load operation flexibility from 30% to 100% •High levels of low frequency with high efficiency; noise; •Can be used in island mode (all ships do this) good •High maintenance costs. load following capability; •Fast start-up time of 15 second to full load (gas •turbine needs 0.5 – 2 hours); •Real multi-fuel capability, can also use HFO as fuel; •Can be overhaul on site with normal operators; •Low investment cost in small sizes; •Can operate with low-pressure gas (down to 1 bar Advantages & Disadvantages Advantages Disadvantages Stirling •Technical advantages: •Little experience in low power engines •Much experience in high power range; range; •Less moving parts with low friction; •Poor shaft efficiency by the •No internal burner chamber; existing •High theoretical efficiency; •machines (350 –800 Watt shaft power); •Suitable for mass production. •Better efficiency at 3,000 Watt •Advantages for micro-cogeneration: shaft power; •No extra thermal-boiler necessary; •First machines have been/are •Electricity production independent from heat very expensive. •production; •Very low emissions; •Easy to control; •Can be built as an interchangeable unit. Application of Cogeneration • Scale of application : Large scale – small scale. • Heat usage : Special – process. • Technology : Backpressure, Gas turbine, Combined cycle, gas engine. • User : One user – more users. • Ownership : User – cooperation. Application of Cogeneration Industrial: • Pharmaceuticals & fine chemicals • Paper and board manufacture • Brewing, distilling & malting • Ceramics • Brick • Cement • Food processing • Textile processing • Minerals processing • Oil Refineries • Iron and Steel • Motor industry • Horticulture and glasshouses • Timber processing Application of Cogeneration Buildings: • District heating. • Hotels. • Hospitals. • Leisure centres & swimming pools. • College campuses & schools. • Airports. • Prisons, police stations, barracks etc. • Supermarkets and large stores. • Office buildings. • Individual Houses. Application of Cogeneration Renewable Energy: • Sewage treatment works • Poultry and other farm sites • Short rotation coppice woodland • Energy crops • Agro-wastes (ex: bio gas) Energy from waste: • Gasified Municipal Solid Waste • Municipal incinerators • Landfill sites • Hospital waste incinerators Application of Cogeneration Application of Cogeneration Application of Cogeneration Economic Value of Cogeneration • Depends very much on tariff system. • Heat - avoided cost of separate heat production. • Electricity 1) Less purchase (kWh). 2) Sale of surplus electricity. 3) Peak sharing. • Carbon credits (future). Energy Flows Money Flows Rs. Rs. Rs. Economics Usefulness of Cogeneration Technologies • To reduce power and other energy costs. • To improve productivity and reduce costs of production through reliable uninterrupted availability of quality power from Cogeneration plant. • Cogeneration system helps to locate manufacturing facility in remote low cost areas. • Improves energy efficiency, and reduces CO2 emissions therefore it supports sustainable development initiatives. • The system collects carbon credits which can be traded to earn revenue. • Due to uninterrupted power supply it improves working conditions of employees raising their motivation. This indirectly benefits in higher and better quality production. Usefulness of Cogeneration Technologies • Cogeneration System saves water consumption & water costs. • Improves brand image and social standing. • Cogeneration is the most efficient way of generating electricity, heat and cooling from a given amount of fuel. It saves between 15-40% of energy when compared with the separate production of electricity and heat. • Cogeneration helps reduce CO2 emissions significantly. It also reduces investments into electricity transmission capacity, avoids transmission losses, and ensures security of high quality power supply. • A number of different fuels and proven, reliable technologies can be used. • A concurrent need for heat, electricity and possibly cooling indicates suitable sites for cogeneration. Usefulness of Cogeneration Technologies • The initial investment in cogeneration projects can be relatively high but payback periods between 3-5 years might be expected. • The payback period and profitability of cogeneration schemes depends crucially on the difference between the fuel price and the sales price for electricity. • Global environmental concerns, ongoing liberalization of many energy markets, and projected energy demand growth in developing countries are likely to improve market conditions for cogeneration in the near future. Policies in support of Cogeneration • In India, power development is the joint responsibility of the Central and State government. • In fact, Section 44 (1) of E(S) Act 1948 bars any licensee or any other person other than the government or a government corporation from setting up a generating station without the consent of the State Electricity Board (SEB) concerned. • And Section 44 (2A) requires the SEB to consult the Central Electricity Authority (CEA) before issuing a consent for capacities more than 25 MW. In India, cogeneration is synonymous with captive generation. • Thus there was a need to open an alternative route other than private generating companies, where the industries themselves will be interested in meeting their own power demand by pooling resources together. Captive/cogeneration power plants offer such an alternative. Summary • Cogeneration is proven technology. • Cogeneration helps for sustainable development. • Cogeneration improves energy efficiency….. …….if heat is used in a proper way. • Otherwise it is just a bad way of electricity production. • Scale is not a limit for cogeneration. • Right dimensioning is crucial for economic application. • Economic performance will increase because of environmental policy. for your attention “Cogeneration, the path to profit and Sustainable development” Policies in support of Cogeneration • Central Government Policy Initiatives •The Center asked all state Governments in October1995 for the first time to create an institutional mechanism allowing captive/cogeneration power plants an easy and automatic entry through quick clearance, rational tariff for purchase of surplus power by the grid, and third party access for direct sale of power to other industrial units. The Center notified a resolution on "Promotion of Cogeneration Power Plants" on 6 November1996. The basic features are: •It recognized the importance of cogeneration and emphasized its development with the combined objectives of promoting better utilization of precious energy resources in industrial activities and creation of additional power generation capacity in the system. •Captive power plants of any other persons (including juristic persons and excepting generating companies) are not subject to the provisions of Section 29(2) of the E(S) Act. Policies in support of Cogeneration • It recognized that industry in general and a process industry in particular needs energy in more than one form, and if the energy requirements and supply to the industrial units are carefully planned overall efficiency of a very high order is possible to achieve. •Emphasis on institutional mechanisms highlighting the issues involved. •Two basic cogeneration cycles have been identified: •Topping Cycle - Any facility that uses fuel input for power generation and heat for other industrial activities. In any facility with a supplementary firing facility, it would be required that the useful heat to be utilized in the industrial activities, is more than the heat to be supplied to the system through supplementary firing by at least 20%. •Bottoming Cycle - Any facility that uses waste industrial heat for power generation by supplementing heat from any fossil fuel. •Qualifying Requirements A facility may qualify to be termed as a cogeneration facility if it satisfies certain operating and efficiency standards. Policies in support of Cogeneration • Qualifying Requirements for Topping Cycle: •It depends on the type of fuel used as the overall efficiency levels likely to be achieved for power generation varies with the choice of fuel. For coal and refinery bottoms, the sum of useful power output and one half the useful thermal output should be greater than 45% of the facility's energy consumption. For liquid fuel, the sum of useful power output and useful thermal output should be greater than 65% of the facility's energy consumption. •The Facility must be able to supply at least 5 MW of power for at least 250 days in a year. •Qualifying Requirements for Bottoming Cycle: The total useful power output in any calendar year must not be less than 50% of the total heat input through supplementary firing. •Benefits of Cogeneration Systems: •High efficiency - by utilizing the same fuel to provide heat and electricity, and thereby reduce fuel consumption, fuel cost, electric utility bills, and provide economic competitive advantages through a maximized return on investment capital; Policies in support of Cogeneration • More useful energy due to recovery of otherwise wasted heat; and energy conservation; •More environment friendly because of efficient fuel use and reduced air emissions (GHG, sulfur dioxide, nitrogen oxides, particulate) and reduced thermal pollution; •A reliable source of power and process steam or heat. This is particularly important in regions prone to frequent disruptions in electricity supply; •Onsite electricity generation can eliminate losses (8-10%) in the transmission and distribution systems; and •Low gestation period. •Foreign Investment Policy •Foreign investors can enter into a joint venture with an Indian partner for financial and/or technical collaboration and also for setting up renewable energy-based power generation projects. •Liberalized foreign investment approval regime to facilitate foreign investment and transfer of technology through joint ventures. •The proposals for up to 74% foreign equity participation in a joint venture qualify for automatic approval. Policies in support of Cogeneration • 100% foreign investment as equity is permissible with the approval of the Foreign Investment Promotion Board (FIPB). •Various Chambers of Commerce and Industry Associations in India can be approached for providing guidance to investors in finding appropriate partners. •Foreign investors can also set up a liaison office in India. •Government of India is also encouraging foreign investors to set up renewable energy based power generation projects on Build Own and Operate (BOO) basis. •Policy Initiatives at State Government Level •For encouraging investment by the private and public sector companies in power generation through renewable energy, a set of guidelines have been issued by the Ministry of Non-Conventional Energy Sources for consideration by the States. •In addition, some States are providing concession/ exemption in State Sales Tax and Octroi, etc. •Maharashtra allows projects on a co-operative basis also and the Maharashtra State Electricity Board provides equity participation. •Karnataka extends a subsidy of Rs 2.5 million/MW. Success Story Godavari Sugars: • The Godavari Sugar Mills Ltd, Sameerwadi, Karnataka, has a present crushing capacity of 8,500 TCD. The management conceived the idea of setting up a 24 MW high-efficiency cogeneration plant in 1997. • Reliance Energy, Noida was the EPC contractor for the cogeneration project, and Desein (P) Ltd was the project consultant and also the Operations & Maintenance (O&M) contractor for the project for five years. Such an EPC/O&M contract for a cogeneration project was undertaken for the first time in India. The 24 MW cogeneration plant was synchronized with the Karnataka Power Transmission Corporation (KPTCL) grid through a sub-station at Mahalingpur on 16 March 2002. Commercial operation commenced from April 9, 2002. • There is a captive consumption of 6 MW during the season and 3 MW in the off-season and the balance is exported to the KPTCL. Apart from power generation, the cogeneration plant also meets part of the steam requirements of the sugar factory and distillery. • The total project cost of Rs 108 crore was met with loans (Rs 74 crore) from lDBI, Andhra Bank and the State Bank of India (SBI), while the equity was met (Rs 34 crore) with the USAID GEP-ABC grant of Rs 4.2 crore. Success Story Godavari Sugars: • The plant is fully automatic with state-of-the-art technology including triple modular redundancy in all controls. The plant also incorporates the latest version of distributed control systems (DCS). Special Features of the Cogeneration Plant • The highest capacity bagasse -fired boiler in India. • Turnkey EPC/O&M contract for the first time in India. • Fully automatic plant with logic redundancy for all criticial controls. • Mechanized bagasse stacking. • Modern fire-fighting system.
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