Cogeneration= Combined Heat and Power Production=CHP Indrotuction What is CHP? Generation of multiple forms of energy in one system/ device: heat and power or mechanical energy Main targets: to “produce” forms of energy as energy efficiency and environmental sustainability PEE- Primary energy saving….. Kyoto protocol……. What kind possibilities are put into practice to achieve above named target? Fuel Cell?, Wind Energy, Solar, Hydro, Biomass, Waste utilization/gasification, …….DSM CHP is the only way to simultaneously use a variety of fuels to produce heat and electricity with high efficiency and low emissions. What we need to implement CHP?- Heat demand- In technical CHP process electricity is generated and the unavoidable waste heat is used to heat up residential, public and commercial buildings as well as industrial facilities. Example: one should consider CHP analogous to hydropower. In order to have a hydro power plant, there must be a waterfall first. 1
Transcript
Cogeneration=Combined Heat and Power Production=CHP
IndrotuctionWhat is CHP?
Generation of multiple forms of energy in one system/ device: heat and power or mechanical energy
Main targets: to “produce” forms of energy as energy efficiency and environmental sustainability
PEE- Primary energy saving…..
Kyoto protocol…….
What kind possibilities are put into practice to achieve above named target? Fuel Cell?, Wind Energy, Solar, Hydro, Biomass, Waste utilization/gasification, …….DSM
CHP is the only way to simultaneously use a variety of fuels to produce heat and electricity with high efficiency and low emissions.
What we need to implement CHP?-
Heat demand- In technical CHP process electricity is generated and the unavoidable waste heat is used to heat up residential, public and commercial buildings as well as industrial facilities.
Example: one should consider CHP analogous to hydropower. In order to have a hydro power plant, there must be a waterfall first. Similarly, to have a CHP plant, there must be the demand of heating or cooling of the local municipal or industrial facilities available. Therefore, from the physical and economic point of view, the waterfall and the heat demand are both considered as necessary assets for generation of electric power at high efficiency.
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The CHP production offers an excellent way to integrate the local energy supply in such a way that the local needs of industrial steam, domestic hot water, room space heating and possible room space cooling can be combined with parallel production of electric power, as presented in below:
Benefits of CHP?
The energy efficiency of CHP is typically 40% higher than the one with separate production of electric power at a condensing power plant and heat at a heat-only-boiler (HoB), all of them using the same fuel. In other words, the CHP uses 30% less fuel than the separate production
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Electricity
District District DomesticCooling Heating hot water
Steam for SpaceIndustry Heating
CHP Plant
Establishment:
Production of 100 units of electric power and heat requires 310 units of fuel at efficiency of 64,5%, when produced by ordinary gas fired combined cycle condensing power plants and boiler plants but only 222 units at efficiency of 90%, if produced by a gas fired combined cycle CHP plant (Sankey diagram)or
SISEND-INPUTVÄLJUND-OUTPUTKondesatsioon- condensing plantGaasil töötav kombi- gas using CHP module Katel-boilerKaod-lossesSoojusenegia- heatElektrienergia- electricityMaagaas-natural gas
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Separate Production
Fuel 310197 113
Combustion Combustion lossloss 14 Power Heat 7
Condensingloss DH network loss
81 5
Distribution loss 2
Products 100 100
CHP
Fuel 222
Combustion loss15
Distribution loss2 DH network loss
5Power Heat
Products 100 100
Based on solid fuels, the total efficiency is also typically 40% higher than the one with separate production of electric power at a condensing power plant and heat at a heat-only-boiler (HoB), all of them using the same fuel, but the power to heat ratio is lower than with gas;
Based on the CHP technology in small scale, the power to heat ratio is usually lower than with CHP in large scale, but similar benefits in fuel economy and environmental protection can be achieved as with the large plants.
Definition by Heat enginge / its “prime movers”
Internal combustion engines Combustion or gas turbines, Steam turbines Microturbines Fuel cells
100 68
24 U
nits
34 U
nits
6 Units (Losses)
60
40
36 Units (Losses)
= 85%
= 40%
10 Units (Losses)
Conventional Generation (58% Overall Efficiency)
Combined Heat & Power (85% Overall Efficiency)
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Some typical CHP plants and a conventional HoB are presented:
Solid Fuel Fired CHP Plant
The steam boiler using coal, peat or renewable fuels produces steam at high pressure and temperature to be used in a steam turbine either of backpressure or extraction- condensing type. The turbine runs the generator to produce electricity. The plant is relatively expensive but is able to use low-grade fuels at low operational costs.
Remarks:Back-pressure means the low steam pressure prevailing at the end of the steam turbine. The back pressure is needed to produce district heating or steam for industry. Without the backpressure, the steam could expand to zero pressure (vacuum) and produce more electricity than with backpressure. In this case the turbine would be called a condensing turbine designed for separate sole generation of electricity without useful heat. Condensing-extraction means a mixture of a backpressure and a condensing turbine. The steam needed for district heating or industry is extracted from the turbine before led to the final condensing turbine part
Gas Turbine Plant
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Solid Fuel CHP HoBElectricity
Bio fuel Fuel
DH DH
Gas Turbine CHP CHP Engine
Gas fuel DHAir DH
Gas fuelElectricity
Electricity
The flue gases of the gas turbine, run by natural gas or light fuel oil, will be directed to a heat boiler, where the heat is recovered to heating purposes and simultaneously the flue gas temperature is cooled down close to the ambient temperature. The turbine will run the generator to produce electricity. The plant is usually small and economic but with poor power to heat ratio on partial heat load.
CHP Engine Plant.
Fuel oil or natural gas depending on the engine design runs the piston engine of the CHP engine plant. The heat energy of both the flue gases of the gas engine and the engine cooling system will be recovered for useful needs. The power to heat ratio is high but the engine needs a little more maintenance than the gas turbine.
Combined Cycle CHP Plant
Interconnection of the gas and steam cycles will yield more electric energy and at higher efficiency than the cycles separately would do.
Combined (gas and steam) cycle CHP plant in two variants: The upper one is based on gas only and represents a modern plant, whereas the lower one is a new gas turbine integrated to the existing solid fuel fired plant afterwards
Power to heat ratio
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Combined Cycle CHP with Gaseous Fuelsa. New Gas Cycle b. Existing Steam Cycle
Flue gas Electricity
Gas fuel
AirDH
Electricity
Combined Cycle CHP with Solid and Gaseous Fuelsa. New Gas Cycle b. New Steam Cycle
Flue gas Electricity
Gas fuel Solid fuel
AirDH
Electricity
The electric power is the more valuable product of the CHP, because alternatively it is usually generated by other thermal (nuclear or coal driven) power plants in a condensing process at low efficiency.
Waste heat recovery units
The heat recovery boiler is an essential component of the cogeneration installation. It re-covers the heat from the exhaust gases of gas turbines or reciprocating engines.
Manufacturers are developing smaller and smaller systems and nowadays there are micro turbines as small as 25 kWe. In general, micro turbines can generate anywhere from 25 kWe to 200 kWe of electricity. 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.
micro turbine CHP
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. The hydrogen used as fuel can be derived from a variety of sources, including natural gas, propane, coal and renewables such as biomass, or, through electrolysis, wind and solar energy.
Organic Rankine cycle:
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ORC unit
Economic Boundaries of CHP?
The CHP technology is very capital intensive. In order to pay back the high investments,
the annual operation time shall be as long as possible, typically more than 4 000 hours;
the produced heat energy usually covers the major part, 50-80%, of the industrial and/or the municipal heat demand;
the price of fuel and waste heat should be relatively low, and,
The price of the electricity sold to the grid shall be sufficiently high to gain sales revenues.
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0%
20%
40%
60%
80%
100%
0 1 2 3 4 5 6 7 8
Thousand hours
Perc
enta
ge o
f Hea
t Loa
d
Load Bio CHP Gas turbGas engine Many CHPs
Some typical sizes of CHP capacity in a modern DH system with load dispatch
DH opens for efficient integration of combined generation of heating and cooling services in a CHP system.
Basically, the CHP and DH represent well-known technology and every day practice.
CHP covers a substantial portion in the electricity production balance of a number of countries: In Finland 36%, in Denmark 62%, in Germany 11% and in Sweden 6%.
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Centralised versus Decentralised CHP?
In a small municipality there are not many options for optimal structuring of the CHP capacity. In large municipalities, however, there are two main policies for consideration: the centralised and the decentralised CHP.
The centralised CHP, the typical solution, consist of one or a few large plants, which are connected to the DH system. The comparative advantages are as follows:
Low investment unit costs due to economy of scale; Centralised flue gas cleaning benefits from economy of scale; and, Less staff needed due to economy of scale.
The decentralised CHP consists of a number of relatively small CHP units scattered to various parts of the municipality. The comparative advantages are as follows:
Lower costs of DH network investments, because less transmission lines are needed; Step by step expansion of CHP capacity according to needs and resources; and, Possibility to locate the individual CHP units to places where the local heat loads of
the municipality and industry can be combined to the sole CHP plant.
CHP with District Cooling
The 12th International Symposium on District Heating and Cooling, 5-7 september 2010
In The Symposium research regarding district heating and cooling will be presented, but special focus will be on following:• Renewable district heating and cooling• Innovative district heating and cooling technologies • Heat and energy planning relevant to district heating and cooling• Innovative legislation and energy policies relevant to district heating and cooling
Costs of CHPThe investment costs of a CHP plant depend on the size (economy of scale) and type: high with solid and lower with gaseous and liquid fuels.
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The financial viability depends very much on the operation costs and sales revenues being a function of
Power to heat ratio varying from 0,2 up to 1,0 depending on the type and the actual loading of the CHP plant;
The peak load duration time varying from 4 000 to 8 000 hours a year; Variations of heat load on daily and weekly basis during the winter, summer and
intermediate seasons; Relations of fuel prices between natural gas, oil, coal, peat and biomass; Price of electricity for sale to either the low, medium or high voltage grid and
depending on the time of sales; Price of heat for sale to heat customers; Costs of various emissions; Connections to fuel supply, water and heat networks and the electric grid; and, Financial parameters including taxes.
Indicative costs of CHP (2002 )Type of Plant
Combined Cycle
Combined Cycle
Combined Cycle, back -pressure
Gas Turbine
Gas engine
Gas engine
Extraction Plant
Steam Turbine back-pressure
Steam Turbine back -pressure
Fuel Gas Gas Gas Gas Gas Gas Coal Coal BioSize el/heat (MW) 220/200 80/70 80/70 10/18 2/2,7 10/12,5 200/30
020/40 20/40
ProductionElectricityHeat(GWh/year)
990900
360315
360315
4581
912
4556
9001350
90180
90180
Operational hours per year
4500 4500 4500 4500 4500 4500 4500 4500 4500
Fuel priceEUR/MWh
14 15 15 16 16 16 8 8 8
Heat price from CHP-plant, EUR/MWh
16 16 16 16 16 16 16 16 16
Electricity price EUR/MWh
40 40 40 40 40 40 40 40 40
Investmentmillion EUR
155 66 60 6 1,6 7,5 350 40 40
Internal Rate of Return, %
14 11 12 14 9 12 8 8 8
Allocation of CHP Costs to Power and Heat
The allocation of CHP costs to power and heat has been an eternal problem and various solutions have been used in the countries. Basically, the problems and possible solutions are
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demonstrated in below, where the selected allocation method only shifts costs from one side to the other while keeping the total costs constant
Allocation of CHP costs to power and heat.
Remarks: The problem of CHP cost allocation is another traditional chicken and egg problem: The pricing of chicken and eggs depends complete on the market. To cover the costs, and simultaneously, have a fair profit, one has to choose a proper costing (and pricing) of the products. Reducing price of eggs, for in-stance, would require raising the price of chicken to meet constant revenues. The analogy to combined pro-duction prevails here as well, according to which one cannot have production of eggs (electricity) without having a chicken (heat).
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Heat
C
Total Costs = Constant
D?
B
A
Electricity
Competition on Heat Market in Transition Economy:
DH vs. Gas
Problems of DH
Symptom
Reaction of DHE
Losses of DH
Heat Sales
Tariff Change
Heating Costsat Customer
Number of Customers
Heat sales
Heat tariff
Actions
Final result
No Rehabilitation: Business as usual
After DH Rehabilitation:Improved Business
Increasing due to ageing Reducing due to modern technology
Increased due to higher tariff
Reducing due to energy conservation
Reducing due to lost customers and energy
conservation
Slight increase needed to cover fixed costs
Strong increase needed to cover high costs
Reduced in total
Customers escape to Gas Old customers remain with DH
Attracting and connecting new customers to DH
Destruction of DH Success of DH and CHP
Introducing/Improving CHP
Reduced heating costs at customers
Remaining customers forced to look for alternatives
Remaining on the reduced level
Needs to be raised
Falling down
Remains constant
High Losses of DH
High Tariff of DH
High Costs of DH for customers
Unhappy Customers
Poor Quality of DH
CHP Directive of EU
Due to increasing importance of cogeneration, the Commission has proposed a special Directive to stipulate the CHP related approach inside the EU.
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Guarantee of Origin
In general, the combined heat and power production plant, in order to get certified as a high-efficiency cogeneration plant,
