Impact of Solar panels on global climate

Aixue Hu, Samuel Levis, Gerald A. Meehl, Weiqing Han, Warren M. Washington, Keith W. Oleson, Bas J. van Ruijven, Mingqiong He,

Warren G. Strand

DOE/UCAR Cooperative Agreement Regional and Global Climate Modeling Program

Hu, et al., 2016, Impact of Solar Panels on global climate. Nature Climate Change, 6, 290-294, doi:10.1038/NCLIMATE2843.

Energy sources

Fossil fuel 10

18 Jo

ules

Global mean T in RCP8.5: 4oC by 2100 8oC by 2300

World renewable energy

Total energy used in the word: 567X1018J (2012) 18 TW (population 7.0B) So if we could harvest small amount of the available solar energy, it would be enough.

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Model and Experiments: Model: CCSM4, with 1 degree horizontal resolution for all components

Forcing: RCP2.6 (2006-2100)

Experiments: 1. Control – standard RCP2.6 simulation and no solar panels; 2. SPDU – Solar panels are installed in cities and major desert areas; 3. SPDU+UH – Same as in 2, but energy is consumed in urban regions; 4. SPDLess – Solar panels are installed in a limited area.

Assumptions: Solar panels reflect 10% of incoming solar radiation(albedo= 0.1), then convert 30% of the absorbed solar radiation to electricity and this electricity is transported elsewhere (90%*30%=27%). The rest (63%) heats the ground. Solar panel efficiency can reach ~40% for Concentrated PV, Thermophotovoltaic (TPV), Concentrated solar power (CSP)

Regions where solar panels are artificially installed

Green stippling is for reduced solar panel installation experiment

Four experiments: 1. Control 2. SPDU 3. SPDU+UH 4. SPDLess %

TW 2010 2050 2100

All scenarios

If all final energy were solar-electricity

15 30 45

Low scenarios

If all final energy were solar-electricity

14 25 31

Energy demand based on the IPCC AR5

SPDU SPDU+UH SPDLess Power production (TW)

739±5 740±5 59±1

Power production urban only (TW)

48±1 48±1 0

Solar Panel Power Production

Global and regional mean temperature

CCSM4 CMIP5

Power consumed 110 TW 0.84±0.21

Albedo Changes

The Effective albedo in regions where solar panels are installed in SPDU, SPDU+UH and SPDLess experiments is actually larger than that in the Control since part of the solar radiation reaching the solar panels is converted to electricity and consumed elsewhere.

Summary 1. It is unavoidable for human beings to convert the

major energy sources from fossil fuel to renewable energy. Solar energy could be the major energy source in the future.

2. Large scale application of the solar panels could significantly affect the regional and global climate – such as a local cooling.

3. Consuming the solar energy can produce a compensating effect on the surface temperature, leading to an insignificant change of the global mean T, but regionally, especially in urban areas, T still can increase significantly.

DOE/UCAR Cooperative Agreement Regional and Global Climate Modeling Program

DOE/UCAR Cooperative Agreement Regional and Global Climate Modeling Program

Thank You

NCAR is sponsored by the National Science Foundation

This work is funded by the Office of Science (BER), US Department of Energy, Cooperative Agreement No. DE-FC02-97ER62402.

Control Changes from Control SPDU SPDU+UH

Global mean temperature (oC)

15.08±0.13 -0.34±0.12 -0.25±0.12

Land mean temperature (oC)

12.11±0.21 -0.58±0.19 -0.41±0.18

Urban mean temperature (oC)

21.10±0.20 -0.26±0.19 0.84±0.21

Global mean Precipitation (m/yr)

1.131±0.011 -0.012±0.010 -0.009 ±0.011

Land mean precipitation (m/yr)

0.901±0.029 -0.008±0.024 0.000±0.026

Changes of Temperature and Precipitation

Global mean temperature anomaly relative to Control

Results shown later is the 90-yr mean (2011-2100)

Units: TW (1012W) Control Changes SPDU SPDU+UH

Global incident solar radiation (ISR)

97394±151 231±178 (0.24%)

177±166

Land ISR 31709±112 111±113 110±125 Ocean ISR 65685±118 120±151 67±144 Global absorbed solar radiation (ASR)

84801±140 -274±135 (-0.3%)

-284±143

Land ASR 23936±92 -320±88 -315±96 Ocean ASR 60865±113 46±97 31±109

Changes in global incident and absorbed solar radiation

Changes of Surface Temperature and Precipitation in RCP4.5, RCP6.0 and RCP8.5 relative to RCP2.6 in CCSM4

Control Changes from Control SPDU area SPDU SPDU+UH

SPD incident direct solar radiation (TW)

2703±13 35±19 (1.3%) 49±18 (1.8%)

SPD total cloud cover (%) 21.5±1 -1.1±1.3 (-5%) -1.5±1.3 (-7%) SPD absorbed direct solar radiation (TW)

1955±9 -374±3 (-19%) -367±3 (-19%)

SPD reflected direct solar radiation (TW)

748±5 -330±3 (-44%) -330±3 (-44%)

SPD T in desert solar panel region (oC)

16.24±0.25 -2.35±0.34 -2.17±0.38

SPD P in desert solar panel region (mm/yr)

271±47 -41±47 (-15%) -63±40 (-23%)

SPD Albedo 0.295±0.003 .114±0.003 .113±0.003

Changes of climate variables in solar panel installed desert areas

Solar Panels: Three major types of solar panels: 1. Photovoltaic (PV) panels that convert light directly to

electricity 2. Thermophotovoltaic (TPV) panels that convert radiant heat

differentials to electricity via photons 3. Concentrated solar power (CSP) using mirrors or lenses to

concentrate sunlight to heat a fluid in order to drive a turbine and generate power

Efficiency of the solar panels 1. PV ~ 10-20% 2. TPV ~ 40% up to 80% 3. CSP ~ 40% 4. Concentrated PV ~ 40%

SPDU SPDU+UH SPDLess Power production (TW)

739±5 740±5 59±1

Power production urban only (TW)

48±1 48±1 0

Solar Panel Power Production

Achievable solar power in the world range from ~400 to 8800 TW, given the current system performance, topographic limitations, environmental, and land-use constraints (Rogner, H.-H. et al., 2012) Roof area ~40%; if 50% installation PP ~10TW desert area ~40%; PP ~296TW/~24TW

Changes of global and regional mean precipitation

Solar Panels: Three major types of solar panels: 1. Photovoltaic (PV) panels or Concentrated PV 2. Thermophotovoltaic (TPV) panels 3. Concentrated solar power (CSP)

Efficiency of these solar panels can all reach ~40%