economically justifiable demand is a demand that does not exceed the needs for heat or cooling and which would otherwise be satisfied at market conditions by energy generation processes other than cogeneration.
Definition : Cogeneration is the simultaneous generation in one process of thermal energy and electrical and/or mechanical energy; Useful heat is heat produced in a cogeneration process to satisfy an economically justifiable demand for heating or cooling; The heat produced by cogeneration can be delivered through various mediums, including warm water (e.g., for space heating and hot water systems), steam or hot air (e.g., for commercial and industrial uses). It is also possible to do Trigeneration, the production of electricity, heat and cooling. Trigeneration is an attractive option in situations where all three needs exist, such as in production processes with cooling requirements.
Cogeneration technologies Combined cycle gas turbine with heat recovery Steam backpressure turbine Steam condensing extraction turbine Gas turbine with heat recovery Internal combustion engine Micro turbines Sterling engines Steam engines Fuel cells ORC
Other classifications: Topping cycle Bottoming cycle Cogeneration units: Micro-cogeneration means below 50 kWe; Small-scale cogeneration means below 1 MWe. Power to heat ratio (P/H): the ratio between electricity from cogeneration and useful heat when operating in full cogeneration mode
Efficiency coefficient for heat generation only Fuel type Overall efficiencySolid fuels Hard coal/coke 0.88 Peat 0.86 Wood fuels 0.86 Oil, LPG 0.89 Biofuels 0.89 Natural gas 0.9 Biogas 0.7
Efficiency coefficient for electricitygeneration only Fuel type Overall efficiencySolid fuels Hard coal/coke 0.442 Peat 0.390 Wood fuels 0.330 Oil, LPG 0.442 Biofuels 0.442 Natural gas 0.525 Biogas 0.420
Alternatives for heat and electricity supplyCondensing power plant Electricity CHP Electricity Heat energy Heat energy Boiler house
Where can CHP be EconomicallyAttractive?Data Centers Nursing HomesColleges & Universities Office BuildingsEthanol/ Biofuel Process Large Multi-Family Plants ApartmentsFood Processing Plants Refrigerated WarehousesHospitals RestaurantsHotels SupermarketsIce Arenas TheatresChemicals, Pulp & Paper, GreenhousesFabricated Metals, Plastics Wastewater Treatment Facilities
Why is There an Opportunity? Rising Concerns Over – Blackouts/Brownouts – Power Supply Constraints – Marked Increases in Electricity & Fuel Prices Selected Power Outage Costs
Generators Two Types of GeneratorsInduction Synchronous• Requires Grid Power • Self Excited (Does Source to Operate Not Need Grid to Operate)• When Grid Goes Down, CHP System • CHP System can Goes Down Continue to Operate thru Grid• Less Complicated & Outages Less Costly to • More Complicated & Interconnect Costly to• Preferred by Utilities Interconnect (Safety) • Preferred by Customers
CHP Recycles the Waste Heat from PowerGeneration achieving efficiencies of over 80%.
CHP and separate generation Fuel input Output Fuel input Separate generation CHP Power station Electricity Electricity81 35% 43% 35 100 Useful heat53 Heat Boiler house 50% 50 95%Total 134 Total 100 134 − 100 Primary energy savings = = 25% 134
Benefits of CHPHigh Efficiency, On-Site Generation Means : Improved Reliability.(Avoiding business disruptions) 50% less CO2 emissions.(Monetizing Environmental benefits) Up to 80% energy efficient.(Reducing Fuel use) Removes requirement for back-up diesels (Conserve Natural Resources) Can uplift Green Star ratings by 1-2 stars. Usually cost-effective. Support Grid Infrastructure Fewer T&D Constraints Defer Costly Grid Upgrades Price Stability Facilitates Deployment of New Clean Energy Technologies
Environmental benefits 250 200 150 W 100 O h C 2 k / 50O mo h nC 2e a g y s r t f , i 0 2005 2006 2007 2008 2009 2010 2011 2013 2015 2018 2020 CO2 emissions reduced by 75%-90% (44-54 thousand Tonnes/year) Overall efficiency in CHP mode – 89%
Conclusion:The main reasons for higher specific energy consumption in Indian Industries are obsolete technology, lower capacity utilization and poor operating and maintenance practices.EC has received increased attention in India since the mid seventies but its impact is felt at a low face due to inhibiting attitudes, insufficient technical know-how, market distortions, high cost of efficient end use devices, capital shortage etc.There is a need to design interventions in terms of policies and institutions which addresses these issues and create incentives for energy conservation.