Potential Climate Impact of

Large-Scale Deployment of Renewable Energy Technologies

Chien Wang (MIT)

�Desired Energy Output:

supply 10% of the estimated world energy demand in 2100

(1400 EJ/yr; Reilly and Paltsev, 2007)

�Installation Scale:

~4.4 millions 1-MW devices (operating continuously! actual

output varies with wind speed) that would occupy a very

large area!

�Interesting Science Issue:

What are the possible climatic impacts of such a large-scale

installation of windmills?

1. A large-scale installation of windmills

Simulating the Climate Effects of Large-scale

Installation of Windmills

• NCAR CCM3 GCM+slab ocean, T42 (~2.8 degree, 18 layers) resolution

• Simulate windmills based on changes in surface roughness that convert kinetic energy to targeted power outputs

• Land Installation: all grass and shrub regions (~58 M km2)

• Ocean Installation: ocean depth < 200 m(~10 M km2)

• 60-year model runs with and without “windmills”

• Use the last 20-year mean of differences between the 2 runs to isolate the effects of windmills

Red Color: Change of surface momentum Drag (10-3);

known ranges of real windfarms: 5 - 13

Blue Color: Location of oceanic “installation sites”

Wang and Prinn (2010)

What a windmill would do to the atmosphere:

Energy cascade in the planetary boundary layer

Kinetic Energy Turbulent

Kinetic Energy

Molecular and

surface

mechanic

dissipation

Heat and matter

mixing- dKE/dt = dTKE/dt

Windmill =

Converting KE to

Electric Energy

- dKE/dt = dTKE/dt + dCEE/dt

Temperature

Change in the

Lowest Model

Layer

Wang and Prinn (2010)

Not the same story as GHG-caused warming

Wang and Prinn (2010)

Significant changes in

precipitation caused

by the windmills

reflect a substantial

alteration to the

pattern of

atmospheric general

circulation

Precipitation

Changes

Wang and Prinn (2010)

The

Reliability

Issue

NA = North America

SA = South America

AF = Africa

AU = Australia

EA = East Asia

Wang and Prinn (2010)

Mysterious Ocean Deployment Story

Wang and Prinn (2010)

Ocean drag

configured in

the model

might be too

large?

Wang and Prinn (2010)

Major Climate Effects of Modeled

Large-Scale Installation of Windmills

• Using land-based wind turbines to meet 10% or more of global energy demand in 2100 could cause surface warming exceeding 1oC over land installations

• Surface cooling exceeding 1oC is computed over ocean installations, but the validity of simulating the impacts of wind turbines by simply increasing the ocean surface drag needs further study

• Significant warming or cooling remote from both the land and ocean installations, and alterations of the global distributionsof rainfall and clouds

• Intermittency of wind power on various time scales poses a demand for one or more options to ensure reliability

• High-resolution climate modeling, process modeling, and field observations are needed

2. Large-Scale Deployment of Solar Panel

� NCAR CCM3 +slab ocean,

T42 (~2.8 degree, 18 layers)

resolution

� Assume solar panels reduce

grid albedo by 0.02, 10%

conversion efficiency

� Solar panel arrays

“installed” in Sahara and

Mideast deserts (~10 M

km2)

� 60-year model runs with

and without “solar panels”

� Use the last 20-year mean

of differences between the

2 runs to isolate the effects

of solar panels

Large-Scale Deployment of Solar Panel

3. Two Stories about Indirect Effects of Biofuels:

Ecosystem GHG implication

Year

2000 2010 2020 2030 2040 2050 2060 2070 2080 2090 2100

mill

ion k

m2

0

15

30

45

60

75

90

105

120

135

Food Crop

Pasture

Managed Forest

Biofuel

Grasslands

Shrublands

Natural Forests

Other

Year

2000 2010 2020 2030 2040 2050 2060 2070 2080 2090 2100

mill

ion k

m2

0

15

30

45

60

75

90

105

120

135

Food Crop

Pasture

Managed Forests

Biofuels

Grasslands

Shrublands

Natural Forests

Other

Land Use Evolutions Land Use Evolutions

Deforestation Scenario:convert nature areas to meet

the demand as far as profitable

Intensification Scenario:more intense use of existing

managed land

Melillo et al., (2009)

Two Stories about Indirect Effects of Biofuels:

Ecosystem GHG implication

Year

2000 2020 2040 2060 2080 2100

Carb

on F

lux ( P

g C

O2-e

q )

-180

-150

-120

-90

-60

-30

0

30

60

90Direct

Indirect

Net Land Carbon Flux

Year

2000 2020 2040 2060 2080 2100

Carb

on F

lux ( P

g C

O2-e

q )

-180

-150

-120

-90

-60

-30

0

30

60

90

Direct

Indirect

Net Land Carbon Flux

Year

2000 2020 2040 2060 2080 2100

Net Bala

nce ( P

g C

O2-e

q )

-600

-400

-200

0

200

400

600

800

1000Fossil Fuel Abatement

Net Land Carbon Flux

Fertilizer N2O Emissions

Net Abatement

Net Land Carbon Flux (Negative = Emissions)

Net Carbon Balance

Melillo et al., (2009)

Major Climate Effects of Modeled

Large-Scale Installation of Windmills

• Vegetation and soil carbon effects on biofuels land use are mixed

• Indirect greenhouse gases implication associated with intensive biofuel scenario is very likely

• Extensive reliance on biomass for electricity would have ecosystem GHG implications

• In-depth research through modeling on the potential GHG implication of various scenarios associated with biofuel electricity production is needed

Ecosystem GHG implication of BiofuelsWhat have we learned and what type of research is need

• High-resolution GCM for both wind and solar simulations

• More detailed energy (heat) partitioning, updated conversion rates

• Detailed process modeling (LES, mesoscale models) to support GCM parameterization

• In-depth economic analyses and modeling on the potential GHG implication of various scenarios associated with biofuel electricity production

• Large-scale deployment of renewable technologies in a changing climate

Needed Research