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

5

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 elarson@princeton.edu