bike-fitline.com Power Block Technology for CSP www.renac.de 1
Power Block Technology for CSP Introduction: Conversion of Thermal Energy into Electricity Thermodynamic Basics Rankine Cycle (Steam Plants) Brayton Cycle (Gas turbine plants) Combined cycle plants Other processes Steam Plant Technology Integration of CSP Collectors into Power Plants www.renac.de 2
Working Principle of a Power Block 1. The thermal energy of the solar field is being transferred to a working medium (usually water/steam) Q th Q th 2. A heat engine converts the thermal energy into mechanical energy (spinning axis) Q th E mech 3. A dynamo/generator converts mechanical energy into electricity by breaking the spinning axis E mech E el Most important power block issue for CSP is step 2.) the thermodynamic conversion www.renac.de 3
Temperature and Efficiency Solar field: high operating temperature means high thermal losses Turbine: Thermodynamic cycle effciency improves with temperature (Carnot-Limit) Hence optimum temperature range www.renac.de 4
Clausius Rankine Cycle: Idealised Reference Cycle for Steam Power Plants Working Steps: pump: 1-2: boiler: 2-3: turbine: 3-4: Condenser: 4-1 Thermal efficiency: ηth= ΔW/ΔQin Andrew Ainsworth www.renac.de 5
Joule Brayton Cycle: Idealised Reference Cycle for Gas Turbines Working Steps: compressor: 1 2 combustion chamber: 2 3: idealised turbine: 3 4: UTPB Upper Temperature (turbine inlet): above 1000 C Lower Temperature (turbine outlet): 500 C This high temperature is exhausted to the ambient - potential use? www.renac.de 6
Combined Cycle Plants (Gas Turbine + Steam Turbine) Gas Turbine outlet gas is used as heat source in subsequent steam plant This leads to high efficiencies However only possible with gasified or liquid fuels, usually natural gas Innovative Steam Technologies www.renac.de 7
Main Components in a Steam Plant Intermediate superheating Turbine Boiler Siemens Generator Condenser FhG-ISE Feed water pump Preheaters Condensate pump Total net plant efficiency η el -n et 20 45% (depending on plant size, plant layout and operation parameters) www.renac.de 8
Commercial Info Typical Plant Sizes and Suppliers Fossil steam plants: 500 1000 MW el fuels: hard and brown coal, heavy oil, light oil, natural gas Nuclear steam plants: 1000 1500 MW el Waste incineration, biomass plants 1 50 MW el Solar thermal power plants 1 400 MW el (up to 280 MW el in planning) Suppliers for Steam Plants and Turbines: General Electric, Siemens, Alstom, Mitsubishi www.renac.de 9
Solar Only Plant Solar Field as only heat source 100% solar energy production possible DSG: control aspects in power plants need to be proved E.ON Engineering www.renac.de 10
Solar Plant with Hybrid Heat Source Boiler in parallel to solar field Other fuels can be used: natural gas, biomass, coal, oil Different operation strategies are possible, e.g.: 24 hr-operation load-driven operation E.ON Engineering www.renac.de 11
Solar Plant with Thermal Storage Storage medium is heated during day (loading) Unloading by transferring heat from storage to cycle Solarmillennium www.renac.de 12
Solar Plant with Thermal Storage Andasol power plant (Andalucia, Spain) 50 MW el 7 hrs storage capacity In summer almost 24 hr operation DLR www.renac.de 13
Increase of Full Load Hours (FLH) with TES Increase of power block utilization Overall efficiency of the plant rises due to power conversion at nominal load of turbine Load management according to demand is possible higher revenues DLR www.renac.de 14
Solar Feed Water Preheating power block infrastructure can fully be used, even retrofit of existing plants is possible Reference: Liddell, Australia, combination with coal fired plant Solar field HE 6 Fraunhofer ISE www.renac.de 15
Integrated Solar Combined Cycle (ISCC) Abengoa Solar Solar field is additional heat source for the steam turbine in CC plant Capacities: 200-500 MW el fossil, 30 MW el solar ISCC s being built in Morocco, Egypt & Algeria, possibly soon in Mexico www.renac.de 16
Integrated Solar Combined Cycle Pros and Cons + Little additional invest related to solar + Large capacities are built + Plant is fully operational without solar field - solar fraction very little (2-10% per year) - Dependency on natural gas - Turbine part load losses during non-solar operation if badly designed, additional CC fuel consumption instead of less! - Operators not necessarily motivated to operate solar field Possibly interesting for market introduction, but no longterm concept www.renac.de 17
Conclusions Variety of options for the integration of CSP collectors into power blocks are possible Most CSP power plants are solar only steam plants (with little fossil co-firing) e.g. SEGS I-IX, Nevada Solar 1, Andasol, PS10 Some ISCC plants are under development / construction www.renac.de 18