Microclimate effects of wind farms on crop yields

Reap the Whirlwind Microclimate effects of wind farms on crop yields

Dan Kaffine CU Dept. of Economics and RASEI

7/22/2014

Mo8va8on

• US electricity from wind has grown from <1% in 2007 to nearly 5% currently – growth likely to conKnue • With that growth, increased interest in understanding potenKal posiKve and negaKve externaliKes associated with wind •  Emissions, property values, health, wildlife, grid stability, O&M impacts on fossil fuel plants, jobs

• Given overlap of “Wind Belt” and “Farm Belt” – might wind power affect crops? •  If so, important implicaKons for private and social welfare

Wind belt and farm belt

Why might there be a link?

• We know that climate (temp, precip, etc) affects crops • We also know that wind turbines create “microclimate” effects

•  Mixing of air temperatures •  Mixing of CO2 •  Humidity effects • Wind speed •  Scale 10-‐60km downwind

• Do these microclimate effects also impact crops? •  If so, is it a posiKve or negaKve impact?

Science

Basic idea

•  Examine impact of wind farms on crop yields following Deschenes and Greenstone (2007) – county-‐level panel

𝑦↓𝑐𝑡 = 𝛼↓𝑐 +𝛽𝑊↓𝑐𝑡 + 𝛾𝑋↓𝑐𝑡 + 𝑌↓𝑡 + 𝜀↓𝑐𝑡 

•  Regress yield 𝑦↓𝑐𝑡  in county c at Kme t against wind capacity 𝑊↓𝑐𝑡  •  Control for precipitaKon, temperature, etc in 𝑋↓𝑐𝑡  •  County fixed-‐effects and year fixed-‐effects to remove Kme-‐invariant county characterisKcs and common yield shocks over Kme

•  Data sources •  Wind capacity – EIA-‐860 •  Yields, acreage, producKon – NASS census (every 5 years) •  Precip, temp – various sources

Preliminary work

•  Start by looking at Iowa •  Lots of wind, small counKes •  Average county size is 30 km x 30 km •  99 counKes, 4 censii of data (1997-‐2012) •  Corn is king (also look at soy, oats and silage)

•  First cut: simple county and year FE model • While this ignores important factors, useful first akempt to see if the relaKonship we expect to see exists • Will be further refined in the months to come

Preliminary results -‐ IA Crop yield

Corn grain (bu) 0.0197 11.80* 3,495* 0.0187* 10.24* 3,075*

(0.0136) (7.32) (1,957) (0.0114) (6.18) (1,691)

Wind measure MW MW/sqmi MW/acre MW MW/sqmi MW/acre

County FE Y Y Y N N N

Ag District FE N N N Y Y Y

Year FE Y Y Y Y Y Y

N 396 396 396 396 396 396

Preliminary results -‐ IA Crop yield

Corn grain (bu) 0.0197 11.80* 3,495* 0.0187* 10.24* 3,075*

(0.0136) (7.32) (1,957) (0.0114) (6.18) (1,691)

Soy (bu) -‐0.0030 -‐0.941 -‐206 -‐0.0030 -‐1.16 -‐263

(0.0032) (1.71) (328) (0.0030) (1.58) (310)

Oats (bu) 0.0014 0.963 0.704 0.008 4.84 2.12

(0.009) (4.90) (1.61) (0.007) (4.22) (1.41)

Corn silage (t) -‐0.000 -‐0.715 -‐7.76* 0.002 0.874 -‐1.38

(0.003) (1.69) (4.34) (0.003) (1.39) (3.44)

Wind measure MW MW/sqmi MW/acre MW MW/sqmi MW/acre

County FE Y Y Y N N N

Ag District FE N N N Y Y Y

Year FE Y Y Y Y Y Y

N 396 396 396 396 396 396

Next steps

• Modestly encouraging results •  Lots to do

•  Definitely need to include precipitaKon and temperature data •  More states •  More Census data (<1997)

• Hopefully preliminary finding holds up •  Point esKmate on corn suggests about ~$6/MWh posiKve benefit •  Smaller than ~$30/MWh CO2 avoidance benefit BUT it’s all local •  At 2013 generaKon levels and prices, ~$100 million in benefit to Iowans

Thanks!

•  Email: [email protected]

Microclimate effects of wind farms on crop yields

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