Bioenergy and Deep Decarbonization
Ron Sands
USDA Economic Research Service
Kansas City, Missouri, USA
The 26th Asia-Pacific Integrated Modeling (AIM) International Workshop
National Institute for Environmental Studies, Tsukuba, Japan
3-4 September 2020
Online Workshop
The findings and conclusions in this presentation are those of the author and should not be
construed to represent any official USDA or U.S. Government determination or policy. This
research was supported by the U.S. Department of Agriculture, Economic Research Service.

Outline• Scenarios based on NAVIGATE and AgMIP deepdecarbonization studies• Mitigation scenarios simulated in Future Agricultural
Resources Model (FARM)– Computable general equilibrium– 13 world regions– Five-year times steps beginning in 2011 (base year for
GTAP 9 social accounting matrix) through 2101

• Bio-electricity with CO2 Capture and Storage (BECCS)
and Afforestation become major land uses
• Implications for land use and agriculturalintensification2

Mitigation scenarios
Scenario

Economy-wide CO2 price

BECCS

Afforestation

C30-gr5 with Afforestation
and BECCSXX

X

C80-gr5 with Afforestation
and BECCS

X

XX

C80-gr5 with Afforestation

X

C80-gr5 with BECCSXReferenceXX

The Reference scenario is based on Shared Socio-economic Pathway 2 (“middle-of-the-road).
C30-gr5: CO2 prices reach $30 / t CO2 in 2040 and increase 5% per year thereafter.
C80-gr5: CO2 prices reach $80 / t CO2 in 2040 and increase 5% per year thereafter.

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CO2 price scenarios
1,800
1,600
1,400
1,200
c80-gr5

1,000

c30-gr5$ / t CO2

c80-const

800

c30-const
600
40020002011 2016 2021 2026 2031 2036 2041 2046 2051 2056 2061 2066 2071 2076 2081 2086 2091 2096 2101

Source: NAVIGATE model intercomparison project4

Conceptual demand for “negative emissions”•••“Negative emissions” is not the best term because the general public will not understand what thismeans. “Carbon dioxide removal” is clearer.
As the CO2 price increases, economy-wide demand for emissions decreases and eventually
becomes negative
Can the NAVIGATE price scenarios drive net global CO2 emissions below zero by 2100 in the FARM
model? What model structure can simulate this behavior?
CO2 price$1- CO2 emissions+ CO2 emissions
base-year emissions (2011)

5Bioenergy with CO2 capture and storage (BECCS)•••••Bio-electricity used with CO2 Capture and Storage (CCS)
Energy crop (switchgrass) as feedstock
Joint products of electricity and CO2 removal
CCS becomes active at high CO2 prices, when it is cheaper to capture and store CO2 than pay CO2 priceAt low CO2 prices, the supply of permits cancels demand for permits, and the model operates as if CCS is
not an option
BECCS: biomass with CCS option
permits(supply)

electricityelectricity: biomass without CCS

σ=0

σ=0

biomass-CCS nestbiomass

σ≥0capitalσ=0labor

σ = 0.7
capitalrentBECCS

σ=0biomass

option CCS
σ=3CCS

permits(demand)Note: σ is the elasticity of substitution in production.
σ = 0 means fixed-coefficient with no substitution between inputs.

σ=0

σ = 1.5
capitalelectricity

storeCO26

World CO2 emissions: C30-gr5 scenario
60,00050,00040,00030,000

Reference (SSP2)
Gross Positive CO2

Mt CO2 20,000

Net CO2
Gross Negative CO2

10,00002011 2016 2021 2026 2031 2036 2041 2046 2051 2056 2061 2066 2071 2076 2081 2086 2091 2096 2101-10,000-20,000

Notes: CO2 prices reach $30 / t CO2 in 2040 and increase 5% per year thereafter. Simulations using the Future AgriculturalResources Model (FARM). Gross negative CO2 emissions are from BECCS only. This figure does not include CO2 removal byafforestation.

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World CO2 emissions: C80-gr5 scenario
60,00050,00040,00030,000

Reference (SSP2)
Gross Positive CO2Mt CO2 20,000

Net CO2
Gross Negative CO2

10,00002011 2016 2021 2026 2031 2036 2041 2046 2051 2056 2061 2066 2071 2076 2081 2086 2091 2096 2101

-10,000-20,000

Notes: CO2 prices reach $80 / t CO2 in 2040 and increase 5% per year thereafter. Simulations using the Future Agricultural
Resources Model (FARM). Gross negative CO2 emissions are from BECCS only. This figure does not include CO2 removal byafforestation.

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World CO2 emissions: C80-gr5 no BECCS scenario
60,00050,00040,00030,000

Reference (SSP2)
Gross Positive CO2

Mt CO2 20,000

Net CO2
Gross Negative CO2

10,00002011 2016 2021 2026 2031 2036 2041 2046 2051 2056 2061 2066 2071 2076 2081 2086 2091 2096 2101

-10,000-20,000

Notes: CO2 prices reach $80 / t CO2 in 2040 and increase 5% per year thereafter. Simulations using the Future AgriculturalResources Model (FARM). This figure does not include CO2 removal by afforestation.

9Afforestation and carbon dioxide removal••

Typical range in literature is 0.5 to 3.6 billion tons CO2 per year (IPCC, 2018: Global Warmingof 1.5°C. An IPCC Special Report, page 270).
Scenario in the FARM model––•Carbon pools–––••

Exogenous increase in global forest area over the century
Not clear how this can be incorporated in a modeling framework
Above ground (forest, pasture)
Perennial roots (forest, pasture)
Soil (forest, pasture, cropland)

Carbon stock calculation based on coefficients for each carbon pool and change in area
Preliminary FARM afforestation scenario––––

Increase in forest area of 296 million hectares over 90 years (2011 – 2101)
Cumulative carbon dioxide removal of 109 billion tons CO2 over 90 years
Average removal rate of 1.2 billion tons CO2 per year
Forests are a potential source of feedstock for BECCS, but not included in this scenario

10Land use change•••

Net land use change sums to zero in each scenario.
In afforestation scenario, the increase in forest land is comparable to increase in land forenergy crops (by design).
Afforestation is a major land use, but with much less carbon sequestered. However, there
may be other benefits of afforestation such as biodiversity.

11Land use and agricultural intensification••••

Our measure of intensification is crop calories per hectare per year
Calories as a common unit allows aggregation over food products and crop types, and provides alink from primary crop calories to final consumption of food calories
1 million kcal is approximately the quantity of food calories consumed per person per year
Large-scale BECSS and afforestation is dependent on the crop yield required to maintain the same
diet as in the reference scenario

Scenario
Reference (base year)
Reference (2101)
Mitigation with BECCS (2101)
Mitigation with BECCS and Afforestation(2101)

Food croparea(Mha)
1,466
1,422
1,234
1,107

Energy cropArea(Mha)
736363323

Change inForest area(Mha)+ 22+ 12+ 284

Crop yield(millionkcal / ha)
6.5
9.410.6
11.8

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Summary• Negative emissions from BECCS offset gross CO2 emissions that arevery expensive to reduce (e.g., air transportation)• At very high CO2 prices, global net-CO2 emissions can become
negative, at least in model simulations• Potential remains to reduce remaining gross CO2 emissions (e.g.,electric vehicles, hydrogen for industrial process heat)• Preliminary results for afforestation show limited carbon
sequestration potential relative to BECCS– Forestry is not easy to model and deserves more attention– Natural forests vs. plantation forests– Forests as a potential feedstock for BECCS• Agricultural intensification over 90 years (2011 – 2101)– Crop yield per hectare increases by 44 percent in reference scenario– Crop yield per hectare increases by 80 percent in full mitigation
scenario

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