W. Udo Schröder, 2013 Schröder, W.Udo ESTS Solar Power 1
Partially Sunny World
2 ESTS Solar Power SolarESTS
Need 20 TW world wide harvest sunlight (total insolation 105 TW). Methods: Indirect (thermal) conversion to electricity: concentrated solar power plant (CSP) Passive heating Direct (photon e-,h exciton) conversion to el. :photo-voltaic (PV), amorphous Si, single crystal Si, thin-film, organic W. Udo Schröder, 2013 Free Power: Solar Radiation
Solar Constant 2 4 RSE 8 2 Earth area AE 5.1 10 km
2 1 random exposed to Sun disk of area AREE R A directions SE 4
42AR 3 SATR 4 SE RSSSE 2 4 RSE E 2 8 4 RS 2 RSE=1.50∙10 km ST S 2 1.370kW m RSE Time averaged over spinning earth A 4 A E RSE 2 Seffective S4 0.343 kW m
Albedo reflectivity,E 0.3 ( expt .)
ESTS Solar Power SolarESTS mean power absorbed by Earth' s surface Effect of solar irradiation on Earth surface 2 is non-cumulative thermal equilibrium Seff 1 E S 4 0.240 kW m
퐴푛푔푙푒 표푓 푖푛푐푖푑푒푛푐푒 ≠ 900 푟푒푑푢푐푒푑 푟푎푑 푑푒푛푠푖푡푦 0 ′ 2 푅푂퐶@ 50 푙푎푡푖푡푢푑푒 → 푆 푒푓푓 ≈ 0.170 푘푊 푚 W. Udo Schröder, 2013
Average Daily Insolation 4
August in NY: (2-4)kWh/d·m2
Energy use US-NE:
ESTS Solar Power SolarESTS (20-30) kWh/d·pers, twice that in US-SW
http://rredc.nrel.gov/solar/old_data/ nsrdb/1961-1990/redbook/atlas/
W. Udo Schröder, 2013 Selective Filter Effect of Atmosphere
Adapted from Liou, An Introduction to Atmospheric Intense solar radiation available at wave Radiation, Academic Press, lengths from the UV, over visible to IR. San Diego, 2002. Spectral gaps due to atmospheric absorption. Dispersion by Rayleigh scattering (blue sky) Utilization for electricity production:
Solar thermal (CSP) thermal conversion 5 Photo-voltaic (PV) direct electrical Strong absorption conversion. of solar radiation in IR by atmosphere Important: collectors’ orientation toward Sun
Log scale ESTS Solar Power SolarESTS
Apparent orbits of Sun on sky require different tilt of sensors for best efficiency e. Can vary by De = ±15%.
Concentrated Solar Power= CSP “Receivers” collect and focus sunlight, Tracking for q, f) best efficiency. Adapted from G. Boyle et al., Renewable energy, OUP W. Udo Schröder, 2013 CSP Plants World Wide
Project Country Power Work Fluid Storage Commission
(Mwe) ______6 Liquid Sodium Sodium Steam Nitrate Salt/Water Steam Nitrate Salt/Water Steam Oil/Rock Steam Nitrate Salt Nitrate Salt Nitrate Salt Hitech Salt Hitech Salt Steam Steam, Water Air Ceramics Nitrate Salt Nitrate Salt Steam, sat. Steam
ESTS Solar Power SolarESTS Air Ceramics Steam, sat. Steam, Water Nitrate Salt Nitrate Salt
W. Udo Schröder, 2013
Line-Focus CSP Collectors 7
Steam Line Tracking Mirrors Line Focus
ESTS Solar Power SolarESTS DT = 500- 4000C
Typically, collector fluid=oil, produces superheated steam in a heat exchanger
Currently largest trough systems generate 80 MWe. Overnight heat storage in molten salt (K/Na nitrate) storage tanks (remains liquid in large T range, large heat capacity)
After DOE Energy Efficiency and Renewable Energies. W. Udo Schröder, 2013 Line-Focus CSP Collector
Receiver Tube (oil) 8
“Solar One” Mojave Desert 1982-1988
Planned: 9 power plants in Mojave Desert (3 sites), total
ESTS Solar Power SolarESTS 6 2 354 MWe, 2·10 m collector area.
Efficiencies e = 0.16-0.18
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Solar Tower Power Plant 9
Tracking Heliostats ESTS Solar Power SolarESTS
1982-1988: “Solar One”, 10-MW plant (Barstow/CA). 1996-1999: “Solar Two”, 10-MW, molten nitrate salt as primary medium. Spain: several operational thermal (water/steam) tower plants, 11-20 MW
W. Udo Schröder, 2013
Heliostat Tracking Mirrors
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The Solar One “proof of principle” project produced 10 MW of electricity. Used 1,818 heliostat tracking mirrors, each covered area of 40 m² (430 ft²). Total area = 72,650 m² (782,000 ft²).
W. Udo Schröder, 2013 Crescent Dunes Solar Energy Project
The US Department of Energy invested $737 million into the Crescent Dunes Solar Energy Project in Nevada. Can generate power into the
11 night by using molten salt as energy storage medium.
≈ 20,000 heliostats focus sunlight onto receiver and heat working fluid (K/Na Nitrate salt) to 5660C.
Salt retains its thermal energy for a relatively long time. Mixed with water produces steam to drive
turbines and electric generator. ESTS Solar Power SolarESTS e ≈ (10-15)% predicted.
W. Udo Schröder, 2013 Distributed Energy Storage Techniques
Mechanical energy storage Gravitational, pumped hydropower,
compressed-air, flywheels 12 Electrical/Electrochemical storage Super capacitors, supercon magnets Batteries: Lead-acid, Ni-Cd, Li-ion, redox- flow/fuel cells
Chemical energy storage
Water dissociation hydrogen ESTS Solar Power SolarESTS Thermal energy storage Change in internal heat energy (“sensible heat”), Phase change (transition) latent heat molten salt storage, thermo-chemical heat
W. Udo Schröder, 2013
Survey: Electricity Storage Technologies
13 Energy: Energy: Science Technology Society&
http://redmountaininsights.com/Utility-Energy-Storage-Market-Guide-I3550?ref=cc
W. Udo Schröder, 2012 Thermal Energy Storage Materials
Physical properties (i) Favorable phase equilibrium. (ii) High density. (iii) Small volume change. (iv) Low vapor pressure.
14 Kinetic properties (i) No supercooling. (ii) Sufficient crystallization rate.
Chemical properties (i) Long-term chemical stability. (ii) Compatibility construction materials (iii) No toxicity. Thermal properties (iv) No fire hazard.
(i) Suitable phase-transition temperature. ESTS Solar Power SolarESTS (ii) High latent heat of transition. Economics (iii) Good heat transfer. (i) Abundant. (ii) Available. (iii) Cost effective. Recent review of PCM storage materials: A. Sharma et al., Renewable and Sustainable Energy Reviews 13 (2009) 318– 345
W. Udo Schröder, 2013 Heat Transfer/Thermal Storage Materials
For design of large production facilities, accurate physical and thermodynamic properties of must be known.
Required data:
15 a) melting point; b) viscosity; c) apparent heat of fusion; d) thermal conductivity; e) heat capacity; f) density; g) volumetric expansion;
h) vapor pressure. ESTS Solar Power SolarESTS
“Designer materials” for heat transfer: mixtures of Water: cp(H2O)= 4.184 J/(g·°C) salts, control various thermodynamic parameters. CvH = 74.539 J/(mol·K) (25 °C) Water or oil have limited temperature range for liquid Heat of fusion =333.6 J/g phase vapor requires pressure vessels, pipes. Molten salts = good compromise. Cordaro et al., Sandia Lab, 1980s.
W. Udo Schröder, 2013 Nitrate Salts: Thermodynamic Properties
Non-ideal mixtures: Non- linear behavior, not proportional to mole fraction.
Large enthalpy of fusion 16 stores large amount of energy in molten phase, recover upon fusion (solidification).
Na/K nitrates (NaNO3, (KNO3) have suitable thermodynamic
properties. ESTS Solar Power SolarESTS
Water: cp(H2O)= 4.184 J/(g·°C) CvH = 74.539 J/(mol·K) (25 °C) Heat of fusion DHf = 333.6 J/g =6.01J/mol Heat of vaporization DHv = 40.7 kJ/mol Cordaro et al., Sandia Lab, 1980s.
W. Udo Schröder, 2013
Concentrated Solar Power Generation
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Since molten salt is able to reach very high temperatures (over 1000 degrees Fahrenheit) and can hold more heat than the synthetic oil used in other CSP plants, the plant is able to continue to produce electricity even after the sun has gone down.
W. Udo Schröder, 2013 Heat Transfer/Storage
Thermal storage and heat exchange in solid material: Silica sand, ceramicc.
Can be driven directly (store thermal energy by heating silica material), or in reverse (withdraw
thermal energy to heat cold fluid) 18
The early trough plants used mineral oil as the heat-transfer and storage fluid; Solar Two: used molten salt (K/Na Nitrates, DH of
fusion, phase change heat conductivity) ESTS Solar Power SolarESTS
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Heat Transfer/Storage
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W. Udo Schröder, 2013 Updraft Towers
Solar chimney in Principle of operation: Manzanares/Spain Sunlight collector produces hot air, which escapes through chimney and produces
draft driving a turbine.
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An Australian plan: construct (world's first large-scale) solar thermal power station Buronga in New South Wales. 200-MW 'Solar Mission' should produce enough
electricity to power 200,000 homes, reducing CO2 emissions by 750,000 t Turbines are driven by heat rising from the transparent "collector" surrounding the tower.
W. Udo Schröder, 2013
Not To Be: DESERTEC Energy-Association
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Updraft Towers
23 ESTS Solar Power SolarESTS An Australian plan to construct the world's first large-scale solar thermal power station is taking shape at Buronga in the Wentworth Shire of New South Wales. The first 200MW power station in the 'Solar Mission' project will produce enough electricity to power 200,000 households while reducing greenhouse CO2 emissions by as much as 750,000 tonnes.The thermal power station generates electricity when turbines are driven by heat rising from the transparent "collector" surrounding the tower.
W. Udo Schröder, 2013 24
According to the report, the median pre-tax value of such cash incentives ranged from $0.90/W to $1.20/W for systems installed in 2011, depending on system size. These incentives have declined significantly over time, falling by roughly 80 percent over the past decade, and by 21 percent to 43 percent from just 2010 to 2011. (Allan Chen, http://newscenter.lbl.gov/news- releases/2012/11/27/the-installed-price-of-solar-photovoltaic-systems-in-the-u-s-continues-to- decline-at-a-rapid-pace/)
An interesting consideration regarding cost-effectiveness and subsidies is that in its early Energy: Energy: Science, Technology, Society years, nuclear fission technology received subsidy support of $19 per kilo watt hour produced, compared to $8.90 per kilo watt hour for solar, and just $0.57 per kilo watt hour for wind power [ Badcock, J., and Lenzen, M. (2010). Subsidies for electricity-generating technologies: A review.Energy Policy, 38, 5038-5047.].
W. Udo Schröder, 2012 Arnett Public Library Solar System
Solar panel installed power 50kW @ $3.15 / W installed Capital investment $157,000.00 24.7kWh per day in Jan 2013 1kW continuous power
25 e 0.02 (2%) Energy: Energy: Science, Technology, Society
W. Udo Schröder, 2012 • The Manzanares solar chimney was a prototype built in Spain in the early 1980's. The experimental chimney was financed by the German and Spanish governments and operated successfully for 7 years.
• The chimney had a diameter of 10 m and a height of 200 m. The base of the chimney 26 was surrounded by a 200 m diameter greenhouse with an open outer rim. The transparent plastic roof of the greenhouse was 2 m above the ground. A vertical axis turbine consisting of a rotor similar to a helicopter rotor drove an electrical generator. The greenhouse increased the air temperature 20°C above ambient. The maximum electrical power output was 50 kW. The power output was steadier than that of conventional wind turbines. The solar chimney would start automatically shortly after sunrise, synchronize and connect to the Spanish electrical grid. The chimney was supported with guy wires. Unfortunately the chimney was eventually
blown down in a wind storm. ESTS Solar Power SolarESTS
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W. Udo Schröder, 2013 Eco Footprint
Solar energy technologies have the potential to satisfy a major portion of U.S. electricity 19 demands as an alternative to fossil fuels, reducing greenhouse gas emissions. But utility-scale 20 solar power systems require substantial land, and at least in the case of solar thermal facilities, 21 water is also required. A recent Department of Energy study 29 concluded that meeting 14% of the 22 U.S. demand for electricity with solar power by 2030 could require twice the land area of 23 Delaware and, depending on the cooling technology, significant water resources . • Another technology for utility-scale electricity 28 generation – concentrating solar systems, requires up to 15 acres per MW and wet cooling 29 (DOE 2012). consumes 1,040 gallons of water per MWh ( • DOE 2012). Land and biodiversity constraints were 1 amply illustrated with the suspension of a concentrating solar power (CSP) farm, the $2.2B BrightSource Energy solar farm in the Ivanpah Valley, CA, when desert tortoise relocation and 3
protection cost the company as much as $40M (Cart 2012; Wang 2011). 4 ESTS Solar Power SolarESTS
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US Solar 2011
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W. Udo Schröder, 2013 Price/Performance
Average prices of photovoltaic cells and modules per peak watt of capacity shipped 33 have declined steady over the past several years. For photovoltaic cells, the average price has decreased more than 18 percent, from $1.13 in 2010 to $0.92 in 2011, and the average price of photovoltaic modules fell nearly 19 percent,
from $1.96 in 2010 to ESTS Solar Power SolarESTS $1.59 in 2011(Figure 2 and Table 4) Efficiency = percentage of incident solar energy (input) converts to electricity (output) under standard rating conditions. In 2011: •16 percent for Crystalline Silicon PV module. •11 percent for Thin-film PV module. •29 percent for Concentrator PV module.
W. Udo Schröder, 2013 n 2011, 1,161,589 peak kilowatts of PV modules were manufactured in the United States. This is 9 percent more than in 2010. Manufacturers in California, Ohio, Oregon, and Tennessee produced almost 75 percent of the domestically manufactured PV modules (Table 7). Crystalline silicon accounted for more than 64 percent of the annual domestically manufactured PV modules, followed by thin-film modules with nearly 32 percent. Together, crystalline silicon and thin-film accounted for more than 96 percent of all PV manufacturing.
34 Imports of PV modules shipments totaled 3,323,865 peak kilowatts in 2011. The predominant type of import shipment was crystalline silicon modules, accounting for nearly 81 percent (2,678,848 peak kilowatts) of total imports. China (51 percent), the Philippines (21 percent), and Malaysia (16 percent) accounted for about 88 percent of total import shipments (Table 8).
U.S. PV module shipments to grid-connected distributed PV systems in 2011 accounted for 2,152,947 peak kilowatts, or nearly 74 percent of the domestic market. Of the domestic shipments to grid-connected distributed PV systems, 96
percent was crystalline silicon, ESTS Solar Power SolarESTS
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Alternating current and direct current (AC and DC). To compare EIA's lower bound with solar industry estimates, it is important to consider the units with which they are described. Organizations
like IREC and the Solar Energy Industries Association report in MWDC, because solar panels produce DC power. EIA collects electric capacity data in MWAC, the type of electricity used in homes and on the grid, and which is produced by non-PV generators. Moving the electricity from the solar panel to the grid involves some losses, and equipment and other considerations differ from installation to installation. W. Udo Schröder, 2013
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Price: € (0.2-0.3)/kWh
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• Nitsch et al., Schluesseltechnologie Reg. En.
W. Udo Schröder, 2013 Abbildung 4.6 zeigt den voraussichtlichen zeitlichen Verlauf der Kosten für importierten Solarstrom aus dem Maghreb bis 2020. Die Investition für eine Hochspannungs-GleichstromÜbertragungsleitung (HGÜ) mit 2.000 MW Leistung über eine Strecke von etwa 3.000
km 39 liegt heute bei etwa 5 Mrd. DM. Für die Übertragung von Solarstrom aus dem Maghreb nach Deutschland durch HGÜ wären Kosten von etwa 5 Pf/kWh zu veranschlagen, d.h. Solarstrom aus solarthermischen Kraftwerken aus dem Maghreb könnte in Deutschland heute für etwa 23-25 Pf/kWh bereitgestellt werden. Unter der Voraussetzung, dass die Markteinführung solarthermischer Kraftwerke wie vorab geschildert erfolgt, wäre ab 2010 ein Kostenniveau von unter 15 Pf/kWh für solaren Importstrom in Deutschland erreichbar. Zu diesem Zeitpunkt könnte mit der Realisierung einer solchen Infrastruktur
ESTS Solar Power SolarESTS begonnen werden.
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• Scientific American
40 ESTS Solar Power SolarESTS
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Energy Storage
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W. Udo Schröder, 2013 In 2010 the largest concentrating solar power plant since the 1980s was completed when Florida Power and Light installed a 75 MWAC
CSP plant near Indiantown, Florida.
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Seventy-nine percent of total solar water heating installations in 2009 was on residential buildings. Contrast that with photovoltaics where residential installations were only 29% of the total installations in 2010. Diversification indifferent market sectors has helped PV growth sustain itself year after year.
W. Udo Schröder, 2013 • Nevada’s new molten salt solar plant will be run by rocket scientists from Pratt and Whitney. Companies such as SolarReserve have championed the use of molten salt in solar thermal projects because unlike water, it retains heat for a very long time. In this case, it is hoped that the plant will continue to produce power for 12 hours after the sun has set. The National Solar Thermal Test Facility has conducted several
44 studies and concluded that molten salt is the most efficient material when it comes to storing the sun’s heat. • In the report, it was stated that, “molten salt is used in solar power tower systems because it is liquid at atmosphere pressure, it provides an efficient, low-cost medium in which to store thermal energy, its operating temperatures are compatible with today’s high-pressure and high-temperature steam turbines, and it is non-flammable and nontoxic.” Another benefit of salt is that it is very widely available as a natural resource, therefore costs are cheaper too. •
Read more: Nevada's New Molten Salt Solar Plant Will Produce Power Long After the Sun Sets | Inhabitat - Sustainable Design Innovation, Eco Architecture, Green ESTS Solar Power SolarESTS Building
W. Udo Schröder, 2013 Sicily Molten Salt
Since molten salt is able to reach very high temperatures (over 1000 degrees Fahrenheit) and can hold more heat than the synthetic oil used in other CSP plants, the plant is able to continue to produce electricity
45 even after the sun has gone down.
Some CSP plants use molten salt storage in order to extend their operation, but collectors rely on oil as the heat collection
ESTS Solar Power SolarESTS medium. 2 heat transfer systems (oil-to-molten-salt +molten-salt-to-steam) increases the complexity, decreases efficiency of the system. The salts used in the system are also environmentally benign, unlike the synthetic oils used in other CSP systems. W. Udo Schröder, 2013
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IREC 2012 Updates & Trends Report W. Udo Schröder, 2013
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W. Udo Schröder, 2013 PV 2011
Utility-sector PV installations more than doubled in 2011 compared to 2010. The utility sector’s share of all U.S. gridconnected PV installations grew from virtually none in 2006 to 15% in 2009, to 32% in 2010, and to 38% in
2011. Of the 10 49 largest PV installations in the United States, five were installed in 2011. In 2011, 81 utility-sector installations larger than 1 MWDC were installed with a total capacity of 640 MWDC. These large installations were 92% of the utility-sector installations in 2011. The two largest U.S. PV installations installed
ESTS Solar Power SolarESTS in the U.S. in 2011 were the 49 MWDC Mesquite Solar 1 Plant in Arlington, Arizona, which supplies power to Pacific Gas and Electric Co. customers in northern California, and the 35 MWDC plant in W. Udo Schröder, 2013 Webberville, Texas, which supplies power to Austin Energy.
Solid-State Physics
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Cost of PV cells US$/W 51
Cost of Si US$/kg Si ESTS Solar Power SolarESTS
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According to the report, the median pre-tax value of such cash incentives ranged from $0.90/W to $1.20/W for systems installed in 2011, depending on system size. These incentives have declined significantly over time, falling by roughly 80 percent over the past decade, and by 21 percent to 43 percent from just 2010 to 2011. (Allan Chen, http://newscenter.lbl.gov/news- releases/2012/11/27/the-installed-price-of-solar-photovoltaic-systems-in-the-u-s-continues-to-
decline-at-a-rapid-pace/) ESTS Solar Power SolarESTS
An interesting consideration regarding cost-effectiveness and subsidies is that in its early years, nuclear fission technology received subsidy support of $19 per kilo watt hour produced, compared to $8.90 per kilo watt hour for solar, and just $0.57 per kilo watt hour for wind power [ Badcock, J., and Lenzen, M. (2010). Subsidies for electricity-generating technologies: A review.Energy Policy, 38, 5038-5047.].
W. Udo Schröder, 2013 Arnett Public Library Solar System
Solar panel installed power 50kW @ $3.15 / W installed Capital investment $157,000.00 24.7kWh per day in Jan 2013 1kW continuous power
56 e 0.02 (2%) ESTS Solar Power SolarESTS
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Green Buildings 57
UT Dallas student service building. Leadership in Energy and Environmental Design (LEED) consists of a suite of rating systems for the design, construction and operation of high performance green buildings, homes and neighborhoods. Developed by the U.S. Green Building Council (USGBC), and spearheaded by Robert K. Watson, Founding Chairman LEED Steering Committee from 1995 until 2006, LEED is intended to provide building owners and operators a concise framework for identifying and implementing practical and measurable green building design, construction, operations and maintenance solutions. ESTS Solar Power SolarESTS Since its inception in 1998, the U.S. Green Building Council[5] has grown to encompass more than 7,000 projects in the United States and 30 countries, covering over 1.501 billion square feet (140 km²) of development area.[6] The hallmark of LEED is that it is an open and transparent process where the technical criteria proposed by USGBC members are publicly reviewed for approval by the almost 20,000 member organizations that currently constitute the USGBC. The Green Building Certification Institute (GBCI) was established by USGBC to provide a series of exams to allow individuals to become accredited for their knowledge of the LEED rating system. This is recognized through either the LEED Accredited Professional (LEED AP) or LEED Green Associate[7] (LEED Green Assoc.) designation. GBCI also provides third-party certification for projects pursuing LEED.
W. Udo Schröder, 2013
TU Darmstadt
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W. Udo Schröder, 2013 Sustainable Energy Strategy
Goals: Maximum possible energy security and independence Criteria for a sustainable energy strategy (based on existing reality)
• provides safe energy supply;
59 • enhances energy independence;
• allows for flexible response to a variable mix of energy demands;
• accounts for existing infrastructure and its evolutionary inertia;
• does not rely on future technological breakthroughs, but is adaptable;
• does not waste useful resources;
• is acceptable to the public. ESTS Solar Power SolarESTS
Diversity of technologies desirable, ramp up most potent candidates now.
W. Udo Schröder, 2013
• NCADAC
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http://www.pv- tech.org/news/polysilicon_demand_outpaci
ng_silicon_per_watt_reduction_strategies ESTS Solar Power SolarESTS
Source: GTM Research http://www.greentechmedia.com/articles/read/global -pv-prices-will-increase-nine-percent-in-2014 W. Udo Schröder, 2013