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Electricity: Fuel of GDP
Where Does Electricity Come From?
Heat
Heat Makes Steam
Steam Becomes Electricity
Best efficiency at highest temperaturePrimarily limited by materials
Thermal Power Generation
½ all US potable water used here
It’s not the heat,
• 40% of heat energy becomes electricity
• Total heat released is insignificant
It’s not the heat, it’s the CO2
• Each molecule of CO2, during its life in the atmosphere, traps 100,000 times more heat than was released when it formed.
‐ Ken Caldeira, Carnegie Inst.Power generation is over 40% of US and
world CO2 emissions, and is the fastest growing sector.
100,000 times
=
Business As Usual: A Problem
We have a problem
Targets and Methods
http://tinyurl.com/hansen350
Primary Resources: Fuel Supplywaves
SOLAR
World energy use
R. Perez et al.
Wind
GasOTEC
BIO Oil
HYDRO
Uranium
COAL
Solar Thermal Power
• Now competitively priced in US
• At $30/ton CO2, economics drives deployment
• Can deliver 90% of grid power• Thousands of megawatts in contract/construction now
• Needed construction rates achievable
• US 2006 electricity: 92x92 mi
On Peak Pwr is Most Expensive(and fastest growing)
Base Load (coal, nuclear)
IntermediateCombined Cycle
Peaking GT
Solar Is Strategic and Economical
• Summer peak load growing 2x average use
• All “peak” load gas‐fired
• Electricity generation fastest growing use of natural gas
• McKinsey, CERA, Simmons predict doubling++ of US natural gas prices within 5 years
Solar Thermal Power: 1914
Solar thermal power systems
Dish Tower
Trough Linear Fresnel
Concentrate Sunlight50-3000x concentration
Track Sun Position daily/seasonally
Store Heat Energy
Convert Heat To PowerTurbine and Stirling Engines
Economics• Collector Cost Per Area• Optical Efficiency• Thermal Losses• Engine Thermal Efficiency
Factors Driving Cost‐Efficiency
• Engine Efficiency
• Reflector Field CostPer Area
• Thermal Losses
α ε σ T4
α Receiver Areaε Emissivity
High Solar Concentration: Materials-limited, cost of precision reflectors and trackers
Lower Concentration: Reductions in reflector cost outweigh lower thermal efficiency
Solar thermal power systemsContinuous Fresnel
Point
Line
Dish TowerStirling Energy SystemsInfiniaAbengoaSolar ReserveBrightsourceTorresol
Solar MilleniumAccionaAbengoa
Ausra
1000-3000 C 550-1000 C
350-450 C 280-380 C
Trough Linear Fresnel
Concept of Tower TechnologyConcept of Tower Technology
Storage
Trough
354 MW Solar Electric Generating Systems (SEGS)
Solar Energy Generating Systems (SEGS)
l
Linear Fresnel
177 MW, 1 square mile
28Carrizo Energy Farm for PG&E in CA; rendering; Online 11/10
Solar Field Costs (Reflector + Receiver) DLR 2007 assessment of solar thermal pwr AQUA‐CSP
Variable ε:Selective Surfaces
Solar Thermal Plant Elements
31
Thermal Energy StorageChallenges
Highly specific design specifications regarding: primary HTF ‐ pressure ‐ temperature ‐ power level ‐ capacity
Storagesystem
ONE single storage technology will not meet the unique requirements of different solar power plants
Thermal Energy Storage for CSP Plants Status und Development
• Commercially available storage systems– Steam Accumulator– 2‐Tank sensible molten salt storage based on nitrate salts
• Alternative materials and concepts tested in lab and pilot scale– Solid medium sensible heat storage ‐ concrete storage– Latent heat ‐ PCM storage– Combined storage system (concrete/PCM) for water/steam fluid– Improved molten salt storage concepts– Solid media storage for Solar Tower with Air Receiver (e.g. natural
rocks, checker bricks, sand) • Future focus for CSP
– Higher plant efficiency => Increase process temperature– New fluids: steam, molten salt, gas/air
Steam AccumulatorsPS10
Saturated steam at 250°C50 min storage operation at 50% load
Molten Salt Storage – Andasol 1
Ø 38,5 m
14 m
292 °C 386 °C
• Storage capacity 1010 MWh (7.7h)
• Nitrate salts (60% NaNO3 + 40% KNO3)
• Salt inventory 28.500 t• Tank volume 14.000 m³• 6 HTF/salt heat exchangers
Storage: Meet Peak Demand++
Least Cost per kWh around 14 hrs storage
Optimal economics depend on tariff
California pays 2x/kWh noon-8pm M-F
Spain, others no TOD
Solar Thermal can supplyover 95% US Grid Power
Mills & Morgan, SolarPACES 2008
11
Solar Thermal vs Conventional ‐ 2013
$/MWh
39
Land is not (remotely) a constraint
More than 90% of world pp could be servedby clean power from deserts (DESERTEC.org) !
world electricity demand
(18,000 TWh/y)
can be produced from
300 x 300 km²
=0.23% of all deserts
distributed over “10 000” sites
Gerhard Knies, CSP 2008 Barcelona 40
US Solar Resource
100%US electricity92x92 miles
World Solar Resources
42
High Voltage Direct Current (HVDC)Low‐Loss (3%/1000 km)
CoR White Paper 2007
Sun-belt + technology belt
• synergies
• interconnection
• technology cooperation
deserts + technology
for energy, water and
climate security
Gerhard Knies, Taipei e‐parl. + WFC 2008‐03‐1/2
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Interstate Highway System
HVDC SuperhighwaysInterchanges to today's hubsStability, Cost, Job Growth, Energy + Climate Security
Can this be done?Give us 100% Clean Electricitywithin 10 years.
• 800 GW by 2017
• 80 GW/yr build!
• Resource availability
• Readiness of technology
• Transmission corridors
• Cost of power
• Reliability of supply
US Power Generation 50 yr History
www.eia.doe.gov
47
Market forces caused 70 GW/yr buildout
China building >100 GW/yr
Can we build 80 GW/yr? Yes Can
48http://tinyurl.com/perez-v-08
