Sustainable Transportation Energy with Net Negative Carbon
Emissions* Eric D. Larson
Energy Systems Analysis Group Andlinger Center for Energy and the Environment
Princeton University
GCEP Research Symposium 2015: Driving Change in the Energy Field Global Climate and Energy Project, Stanford University
Palo Alto, CA, 13-14 October 2015
with co-investigators Robert Williams, Princeton University
David Tilman and Clarence Lehman, University of Minnesota
* The investigators thank Stanford University’s Global Climate and Energy Project for funds supporting this research.
Motivating Assumptions • Carbon-bearing liquid fuels, with high energy densities and vast
established physical infrastructure, will continue to play dominant roles in transportation for at least several decades.
• Continued “business-as-usual” for transportation energy will contribute to likely global warming exceeding the 2oC threshold agreed to by world leaders.
• Staying below 2oC global warming will likely require deployment of energy systems characterized by net negative greenhouse gas (GHG) emissions, key among which are technologies using biomass-energy with CO2 capture and storage (BECCS). – “Many (integrated assessment) models could not limit likely warming to
below 2°C if bioenergy, CCS, and their combination (BECCS) are limited (high confidence).” [IPCC, AR5, WGIII]
• The scarcity of sustainable biomass supplies relative to energy needs requires innovative and judicious approaches, including coordinated use of biomass and fossil fuels in transition term.
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Schematic Lifecycle Carbon Balance bi
omas
s up
stre
am e
mis
sion
s
coal
ups
trea
m e
mis
sion
s
char
coalve
hicl
e ta
ilpip
e
CO2storage
fuel
flue
gase
s
phot
osyn
thes
is
biomassem
issi
ons
biom
ass
upst
ream
em
issi
ons
Production Facility
fuel
com
bust
ion
3 Larson, Fiorese, Liu, Williams, Kreutz, Consonni, “Co-Production of Synfuels and Electricity from Coal + Biomass with Zero Net Carbon Emissions: An Illinois Case Study,” Energy and Environmental Science, 3(1): 28-42, 2010.
soil / roots
Project Goals • Identify and analyze promising biomass-based pathways to net
negative carbon emissions for transportation by mid-century. – Field studies of potential lignocellulosic (non-food) biomass-energy supplies
from degraded lands in the U.S. (estimated > 450 million acres) – Alternative bioconversion technology assessments – Integrated techno-economic bio production/conversion systems analyses. – Assessment of potential for commercial deployment of competing options – Quantification of national potential, using residues and degraded lands.
Ecosystems (UMN)Carbon storage and
sustainability of biomass production
Energy Systems (PU) Fuels and electricity
technologies modeling and lifecycle evaluation
Biomass yields, carbon storage,
ecosystem impactsTechnologies,
economics, lifecycle carbon and water
Sustainable negative C emissions transportation
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Process designs & simulations for making - hydrocarbon
liquid fuels (non-alcohol)
- with CO2 capture and storage
- from biomass - from biomass +
fossil fuels
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light hydrocarbons
heavy hydrocarbons
biomass
Sizing & drying
Catalytic hydro-
pyrolysis
Hydro-deoxygenation Distillation
Pressure swing ads.
char electricity
Pressureswing ads.
Steam Reformer
Water-gas shiftCombustor
combustion product gas
CO2 capture
CO2
Steam & power
air
H2
H2
tail gas
tailgas
fluegas
non-condensable gases
Acid GasRemoval RefineF-T
Synthesis
CO2
Synthetic Diesel & Gasoline
unconverted syngas+ C1 - C4 FT gases
H2 Prod
purge
Powerisland
power
ATRO2 steam
FB Gasifier& Cyclone
Chopping & Lock hopper
biomass
TarCracking
steam
CO2 dry ash
Filter
O2
Air SepPlant
air
CO2
De-acetylate Pretreat
Enzymeproduction
Enzymatichydrolysis
Aerobicmetabolism
Separationupgrading
Waste watertreatment
biomass
cellulase
sugars
CO2
hydrocarbonproduct
waste
brine
Powerisland
off-gas, sludge
H2O, NaOH
waste
off-gases
CO2H2O, chemlignin
H2, catalyst
waste
freefattyacids
substrate,nutrients
power
GASIFICATION
HYDRO-PYROLYSIS
BIOCHEMICAL PROCESSING
Comparative Evaluation Metrics • Integrated set of ecosystem and energy system metrics to help
quantify potential of alternative systems – Net greenhouse gas emissions – Environmental, ecological, and land-use impacts – Economic competitiveness under plausible carbon mitigation
policies – Commercially deploy-ability to meet substantial share of US
transportation service demands by mid-century
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0.0
0.5
1.0
1.5
2.0
2.5
3.0
-2.25 -2.00 -1.75 -1.50 -1.25 -1.00 -0.75 -0.50 -0.25 0.00 0.25 0.50 0.75 1.00
Biom
ass I
nten
sity
(BI)
Greenhouse Gas Emissions Index (GHGI2005)
𝐺𝐺𝐺𝐺2005 = 𝑇𝑇𝑇𝑇𝑇 𝑇𝑙𝑙𝑙𝑙𝑙𝑙𝑇𝑙 𝑙𝑒𝑙𝑒𝑒𝑙𝑇𝑒𝑒 𝑙𝑇𝑓 𝑇𝑡𝑙 𝑒𝑙𝑒𝑇𝑙𝑒
𝐿𝑙𝑙𝑙𝑙𝑙𝑙𝑇𝑙 𝑙𝑒𝑙𝑒𝑒𝑙𝑇𝑒𝑒 𝑙𝑇𝑓 2005 𝑓𝑙𝑙𝑙𝑓𝑙𝑒𝑙𝑙 𝑒𝑙𝑒𝑇𝑙𝑒
Illustrative Energy Balance & GHG Emissions Metrics
1. National Research Council, America’s Energy Future, 2009. 2. Larson, et al., Energy Env. Sci, 3(1): 28-42, 2010. 3. Preliminary work.
𝐵𝐺 = 𝐵𝑙𝑇𝑒𝑇𝑒𝑒 𝐸𝑒𝑙𝑓𝐸𝑙 𝐺𝑒𝐼𝐼𝑇
𝐿𝑙𝐿𝐼𝑙𝐿 𝐹𝐼𝑙𝑇 𝐸𝑒𝑙𝑓𝐸𝑙 𝑂𝐼𝑇𝐼𝐼𝑇
Fischer-Tropsch fuels from coal + biomass, with CCS2
native grasses (18%), with soil/root C storage
corn stover (26%)
Cellulosic ethanol from switchgrass1
No CCS With CCS
from native grasses with soil/root C storage
with CCS no CCS
Fischer-Tropsch fuels2
from corn stover no CCS
with CCS
from forest residues Hydropyrolysis fuels3
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Key Economic Metrics • Capital cost intensity • Internal rate of return on equity • Levelized cost of production
Negative emissions may have high value by mid-century.
Global CO2 emission price trajectory (median) for 2o C scenario. CO2 emission prices estimated by multiple integrated assessment models for different global warming scenarios.
IPCC, 5th Assessment Report, Working Group III Contribution (Figure TS.12).
9
0
10
20
30
40
50
0 100 200
G-FT (CCS)
HPyr (Amine)
Near-term gasification-based fuels from corn stover, with CCS [TRL=7]*
Future hydropyrolysis-based fuels from forest residues, with CCS [TRL=4]
Greenhouse Gas Emissions Price, $/tCO2eq
Lev
eliz
ed B
iofu
el P
rodu
ctio
n C
ost,
$/G
J LH
V (2
014$
)
Different technology readiness levels (TRL) complicate comparisons
* Major cost reduction potential with chemical looping based gasification (focus of RD&D for coal at the National Energy Technology Laboratory) [TRL=3].
Land-Related Sustainability Metrics
• Soil productivity impacts (organic matter, nutrients, erosion) • Water (and air) impacts (N, P, pesticide pollution, etc.) • Loss of ecosystem services and biodiversity • Direct and indirect land use impacts on GHG emissions • Direct and indirect land use impacts on food production
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To minimize negative impacts, use agriculturally-degraded lands for biomass energy production and/or use residues for energy.
Understanding biomass production on degraded lands will build on the Cedar Creek Experiment
Established in 1994 to study the fundamental impacts of biological diversity on ecosystem functioning
168 Plots – Each 9 m x 9 m Random Compositions of
1, 2, 4, 8, or 16 Species
Plus, 184 Plots with 32 Species or Other Treatments
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On degraded soil, high-diversity grasses store C in roots and as soil organic matter
12
Soil Carbon Soil Nitrogen
16
8 2 4
1
13
Diverse plots store more C (and also N) in soil
Soil carbon build-up on degraded soils is projected to continue for over a century, with diverse plots cumulatively storing 35 more tonnes C per hectare than mono-species.
(Fornara & Tilman, Plant functional composition influences rates of soil carbon and nitrogen accumulation, J Ecology, 96: 314-322, 2008.)
Measuring energy content Bales – about one ton each.
Higher productivity (and stability) results largely from interspecies complementarity. With 16 species, productivity was 211% higher than average monoculture and 64% higher than best monoculture species.
2010-2012
Above-ground biomass productivity is higher on degraded soils when species diversity is higher
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Soil
Nitr
ate
Con
cent
ratio
n
Greater root mass with high species diversity enables more nitrate uptake, which improves quality of runoff water
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During summers, biomass is a collection of grasses and flowers, good wildlife habitat.
Prairie bioenergy and wildlife
Wildlife surveys also include birds, mammals, and reptiles.
Quantifying wildlife impact, these researchers are surveying insects, which are essential pollinators and food for birds and small mammals.
Insect surveys are calibrated by exhaustive measures in small plots correlated with the larger-scale measures.
In fall, after vegetation has senesced and migratory wildlife has left, biomass is harvested for energy.
Work at Minnesota will build knowledge of sustainable yields and C impacts, focusing on:
• impact of fertilization on structure and diversity of species, • soil carbon sequestration mechanisms and duration, aimed at
identifying engineering solutions to maximize soil carbon storage, • impact of returning byproducts of biomass conversion to the
land, e.g., inorganic ash and carbonaceous char from gasification • species mixtures that include both early and late-successional
species for rapid initial ramp-up of biomass production, • methods for reestablishing native grasslands on degraded soil
without intensive spraying and tilling that can release stored soil carbon and partially negate the carbon benefits of biomass
• projecting findings to the national scale using models that combine USDA and other geo-referenced databases relating to soils, land uses, hay and crop yields, and current and projected climate patterns and related broad-scale indices. 22
Global Transport-Energy Thought Experiment
23 mpg 19 27 62
GtCO2eq/yr
Larson, et al., “Fossil Energy,” in The Global Energy Assessment, 2012.
(assuming no soil or root C storage)
0.0 ?
IPCC confident of at least 100 EJ/y of sustainable biomass in 2050
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Thank you!
Eric D. Larson Senior Research Engineer
Energy Systems Analysis Group Andlinger Center for Energy and the Environment
Princeton University, Princeton, NJ [email protected]