Heidi Hartmann from Argonne National Laboratory presented on the growth of utility-scale solar development in the US and potential benefits of establishing pollinator habitat at solar sites. Utility-scale solar capacity grew 93% annually between 2008-2018, with 33.8 GW installed in 2018 across 275 square miles. Typical construction clears vegetation but some companies now use low-impact methods like leaving plants. Establishing pollinator habitat could help declining pollinator populations while providing agricultural benefits to nearby crops through increased pollination worth millions of dollars annually. Field studies are underway to measure pollinator response at solar sites.

1. Heidi Hartmann
Argonne National Laboratory,
Environmental Science Division
Presentation for Soil and Water Conservation Society
Annual Meeting – Pittsburgh, PA July 30, 2019
Collaborators: Ihor Hlohowskyj and Lee Walston - Argonne; Rob Davis, Fresh Energy;
Brenda Beatty, Jordan Macknick, James McCall - NREL

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SWCS Annual Conference July 30, 2019
Utility-Scale Solar Development in the U.S.
§ Utility-scale solar development grew at an average rate of 93% per year between
2008 and 2018, faster than any other electric generating technology
§ Facility footprints: 6-8 acres per MW
§ 33.8 GW of installed capacity in 2018: corresponds to about 275 mi2 or 711 km2
total footprint
§ Varying growth
projections; the most
conservative estimate
is10-fold growth by 2050
(EIA), DOE projects this
will happen by 2030.
U.S. Installed Capacity (USEIA 2019)

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Impacts of Utility-Scale Solar Development
§ “Typical” construction methods – clear vegetation, grade, leave bare or cover with
gravel or turf grass
§ Important location-specific impacts to consider include loss of habitat (especially for
species status species), soil erosion, dust generation, increased runoff, loss of
wetlands and farm lands
§ “Over the past 2-4 years, many companies are trying “low impact” site development
– leaving vegetation in place or seeding native plants under and around solar
panels after construction
“Typical” site preparation – grading, then gravel or bare soil
“Low-impact” site preparation – pollinator friendly vegetation.
Credit: Dennis Schroder, NREL
SWCS Annual Conference July 30, 2019

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SWCS Annual Conference July 30, 2019
Status of Pollinators is Declining
§ Large loss of grasslands and wetland due to human development (e.g., since 1996
about 167 million acres converted to croplands to support biofuels industry)
§ Significant pollinator declines observed in U.S. and globally – from 2008 to 2013,
wild bee abundance declined across 23% of US land area
§ Winter colony losses of managed honeybees of more than 30% in the mid-2000s –
many causes: queen failure, pathogens, parasites, pesticides, climate change
Health honey bee hive – GA Dept of Agriculture
Mouth to mouth feeding one possible facilitator of CCD (USDA 2012)

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• Regional flowering plants attract and
support insect pollinators by providing
nesting and foraging areas.
• Restores other ecosystem services
(storm water & erosion control, better
soil quality and quantity; carbon
storage; increased biodiversity,
aesthetics, community acceptance
• Agricultural benefits?
A B
C D
No Vegetation Turf Grass
Onsite
Pollinator
Offsite
Pollinator
Establishing Pollinator Habitat at Solar Facilities can
address multiple problems
Photo credit: Dennis Schroeder, NREL
Photo credit: Rob Davis, Fresh Energy

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SWCS Annual Conference July 30, 2019

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– Pest control
– Increased pollination
– Reduced dependence on
commercial pollination
Potential Agricultural Benefits
Pollinator Habitat
Increases Insect
Visitation to
Nearby Crops
Up to 75% of crop
species benefit to
some degree from
animal pollination
(Klein et al. 2007)
Insect pollinators
can increase cotton
boll mass by up to
16.5%
(Rhodes 2002)
Insect pollinators
can increase
soybean production
by up to 18%
(Milfont et al. 2013)
SWCS Annual Conference July 30, 2019

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Examining Potential for Agricultural Benefits from
Pollinator Habitat at Solar Facilities in the US
The first step towards quantifying the pollination service benefits of solar-pollinator habitat was to
identify the areas of co-location where solar-pollinator habitat may be most beneficial to crop production.
CroplandDataLayer,USDANationalAgriculturalStatisticsService
Pollination
dependence:
Klein et al.
(2007) and
Aizen et al.
(2009)
Walston, LJ; SK Mishra; HM Hartmann; I Hlohowskyj; J McCall; J Macknick; Environ. Sci. Technol. 2018, 52, 7566-7576

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Examining Potential for Agricultural Benefits (cont.)
Identified over 1,360 mi2 of
agricultural land near existing and
planned solar facilities that may
benefit from insect pollinators
Summary of Total Pollinator-Dependent
Agriculture Near Solar Facilities
(>0% insect pollination benefit)
Over 20 different crop types
Other dependent
crops include:
Peanuts,
Strawberries,
Cranberries,
Blueberries, Melons,
Beans, Apples,
Pumpkins/squash,
Peaches

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Examining Potential for Agricultural Benefits from
Pollinator Habitat at Solar Facilities in the US
California
Almonds
• The 29,718 ha (73,434 acres)
of almond orchards near solar
facilities in California
represents nearly 8% of the
total almond production in
California, which is an industry
valued at over $5 billion USD.
• A 1% yield increase could be
valued at over $4 million USD.
• Possible additional economic
tradeoffs associated with
reduced honeybee rental fees
($300-$400 per acre).
Massachusetts
Cranberries
• The 1,904 ha (4,705 acres) of
cranberry bogs near solar
facilities in Massachusetts
represents nearly one-third of
the total cranberry production in
the state, which is valued at
about $80 million USD.
• A 1% yield increase could be
valued at over $266,000 USD.
Examples
(Photo credit: University of Maine –
Cooperative Research Extension)
(Photo by Kathy Keatley Garvey, UC-Davis)

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Field Work Activities (Planned 2019-2021)
•2 or 3
Minnesota solar
facilities
•Transect-based
study design
•Surveys to
include onsite
pollinator
habitat as well
as adjacent
agricultural
areas
Measure insect pollinator community abundance and diversity in response to
solar-pollinator habitat establishment

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Baseline Sampling Results – August 2018
• Baseline sampling from seven
transects at each of two solar
sites.
• Little flowering vegetation present
- pollinator-friendly seed mix
newly planted 2 months prior
• More pollinators were observed at
Facility 1 (maximum of
55/transect) than at Facility 2
(maximum of 26/transect)
• possibly due to substantially
higher wind speeds during
sampling at Facility 2.
• At both sites pollinators
observed were mainly
hoverflies. Also a leafcutter
bee, two forage looper
moths, and several
unidentified moth species.

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Year 1 – July - August 2019
• Conducting sampling at 2 sites every two weeks mid July through end of August
• Natives currently in bloom at solar facilities include black-eyed susan, wild bergamot, purple prairie
clover, long-headed coneflower, swamp milkweed, and vervain.
• Interim data comparing pollinator counts to baseline will be compiled/analyzed soon.

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InSPIRE Partnerships
• Partnerships with industry, researchers, seed providers, conservation groups, restoration specialists
• Several groups collecting similar data.
Photos: Monarch Caterpillar and Chrysalis, Eryngium yuccifolium (Rattlesnake Master), Milkweed Field, Ernst Seeds,
Meadville PA

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Quantifying Other Ecosystem Service Benefits
• Solar development and soil and water conservation
• Modeling using region-specific parameters
• Carbon storage estimation
Looking Ahead…
SWCS Annual Conference July 30, 2019

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Work funded by DOE’s Solar Energy Technologies Office
Part of the InSPIRE (Innovative Site Preparation and Impact Reductions on the
Environment) project
https://www.nrel.gov/news/features/2019/beneath-solar-panels-the-seeds-of-opportunity-sprout.html
https://www.anl.gov/article/can-solar-energy-save-the-bees
Thank You!
Heidi Hartmann
Argonne National Laboratoy
Environmental Science
Division
hmhartmann@anl.gov
630-252-6487
SWCS Annual Conference July 30, 2019