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Seeking Synergy Between Technological and Ecological Systems for Sustainable Engineering
Bhavik R. Bakshi
William G. Lowrie Department of Chemical & Biomolecular Engineering
The Ohio State University, Columbus, OH 43210
Department of Chemical Engineering,Carnegie Mellon University, March 26, 2013
Ecosystems and Sustainability
� Availability of ecosystem goods and services (Natural Capital) is essential for sustainability
� It is the source of all other goods and services
� But its role is greatly underappreciated
EconomicProducts &ServicesEconomy
NaturalCapital
Ecosystem
Sun
Drawing Down Natural CapitalRegulating
• Air quality regulation
• Regional and local climate regulation
• Erosion regulation
• Water purification
• Pest regulation
Provisioning
• Capture fisheries
• Wild foods
• Wood fuel
• Genetic resources
Cultural
• Spiritual & religious values
• Aesthetic values
DegradedDegraded
• Pest regulation
• Pollination
• Natural hazard regulation
resources
• Biochemicals
• Fresh water
MixedMixed
EnhancedEnhanced
• Timber
• Fiber
• Water regulation (e.g., flood protection)
• Disease regulation
• Recreation & ecotourism
• Crops• Livestock• Aquaculture
• Carbon sequestration
Anthropogenic Impacts & Ecological Limits
Climate Change
Atmospheric AerosolLoading
Chemical PollutionOcean Acidification
Stratospheric Ozone Depletion
Rockstrom et al., Nature, 2009; http://vimeo.com/anthropocene/shortfilm
Nitrogen cycle
Biodiversity Loss
Depletion
Phosphorous cycle
Global Freshwater UseChange in Land Use
Typical Engineering Response
� Develop new technologies
� Fuels and materials from biomass
� Enhanced oil recovery, fracking
� Genetically engineered crops
� Enhance efficiency
� Process systems engineering has played a key role� Process systems engineering has played a key role
� From process to enterprise scales
� May not solve the problem, but shift it outside the analysis boundary
“The significant problems we face cannot be solved at the
same level of thinking we were at when we created them”
- Albert Einstein
Ecosystem
Economy
Value ChainIncreasing
system scope
and complexity
Increasing
relevance to
global sustainabilityEnterprise
From PSE to Sustainable Engineering
Domain of Process Systems Engineering
Process
Process &
Prepare
Inputs
Fabricate
& Package
Product
Distribute
& Support
Product
Extract
Raw
Materials
Recover,
Recycle or
Dispose
Flows &
Services
Flows &
Impacts
Bakshi, B. R., and J. Fiksel,
AIChE J., 2003
Challenges in Sustainable Engineering
� Consider network of processes across scales
� Choose more “eco-efficient” alternative
Life Cycle Assessment
Life Cycle Assessment
� Aims to consider all processes from “cradle to grave”
� Need data for each stage of life cycle
Production
Extraction
& Processing
Energy Emission
Environment
life cycle
� Energy
� Materials
� Emissions
� Popular and standardized
Use
Disposal
Reuse or
recycleMaterial
Waste
Waste Emission
Carbon Footprint of Selected Biofuels
8E+12
1E+13
1.2E+13
1.4E+13
GasolineDiesel
15
-2E+12
0
2E+12
4E+12
6E+12
CornEthanol
CornStover
YellowPoplar
News-print
Switch-grass
MSW
Life Cycle Approaches in Industry
� “Sustainability Nears a Tipping Point”
� Survey of 4000 managers from 113 countries
� MIT Sloan Management Review (Jan 23, 2012)
Challenges in Sustainable Engineering
� Consider network of processes across scales
� Choose more “eco-efficient” alternative
� Account for role of ecosystem services
� Quantify contribution from nature to human activities
Life Cycle Assessment
� Quantify contribution from nature to human activities
Ecologically-Based Life Cycle Assessment
Eco-LCA Network Model
Zhang, Baral, Bakshi, Env. Sci. Tech., 2010
Framework for Eco-LCA
Equations for Eco-LCA
� Intensity of resource use in each sector,
R = (I – AT)-1X-1vph
aij=zij/xj
� Life cycle resource use for final demand, fnew
vph,new = RTfnew
� Life cycle network analysis,
^
� Life cycle network analysis,
(I – A)-1 = I + A + A2 + A3 + …
� Hybrid Eco-LCA can combine detailed process level information with economy scale model
Direct Indirect
Eco-LCA softwarehttp://resilience.osu.edu/ecolca/
Nitrogen footprint
1.50E+11
2.00E+11
2.50E+11CornEthanol
CornStover
Switch-grass
-2E+12
0
2E+12
4E+12
6E+12
8E+12
1E+13
1.2E+13
1.4E+13
Carbon Footprint
0.00E+00
5.00E+10
1.00E+11
1.50E+11
Gasoline
Diesel
Stover
YellowPoplar
News-print
grass
MSW
Ecosystem Services in Eco-LCA
� PROVISIONING SERVICES
� Fuels
� Crude Oil; Natural gas; Coal; Nuclear fuel
� Ores
� Iron; Copper; Silver; Zinc and lead; Gold; Other metallic ores
� Primary production
� Fish & related species
� Wood
� Grass
� Land
� Cropland; Rangeland and pasture; Timber
� Pollination
� Sunlight
� Hydropotential
� Geothermal
� Wind
� Non-metallic
� Minerals; Crushed stone; Sand
� Water
� Irrigation water
� Thermoelectric power generation water
� Public Supply Water
� SUPPORTING SERVICES
� Mineralization
� Nitrogen, Phosphorus
� Soil
� Nitrogen deposition from atmosphere; Detrital matter; erosion
� Farm, Timber, Ranch
* Work In Progress
Ecosystem Services in Eco-LCA
� REGULATING SERVICES
� Carbon Sequestration
� Yard trimming and food scrap stocks in landfills
� Urban trees
� Soil (land converted to grassland)
� Soil (cropland remaining cropland)
� Forest
� Water Regulation*
� Climate Regulation*
� Disease Regulation*
� Pest Regulation*
� Waste treatment*
� EMISSIONS
� Carbon dioxide
� Fuel combustion� Forest
� Ranchland
� Farmland
� Ocean*
� Reactive Nitrogen Production
� Fixed by microorganisms in soil
� From leguminous plants
� Atmospheric deposition
� Livestock manure
� Fertilizer use (farm and non-farm)
Fuel combustion
� Grassland remaining grassland
� Land converted to cropland
� Urea fertilization
� Liming
� Reactive Nitrogen
� Soil management
� Forest fires
� Burning of agricultural residues
� Manure management
� Many other pollutants
* Work In Progress
Thermodynamic Aggregation
� Aggregation reduces dimensionality
� Why thermodynamics?
� Governs the behavior of all systems
� Exergy (available energy) is the ultimate limitingresource
++−∆= zgv
STHB2
� Provides common currency for the joint analysis of industrial and ecological systems
� Can represent energy and material resources
� Monetary aggregation ignores role of nature
++−∆= zg
vSTHB
20
Eco-LCA Thermodynamic Indices
NNon-Ren
Resources
Sun EcosystemR1 Industrial
Processes
F
Y Economic
Resources
R
� Renewability Index
� R/(F+N+R)
� Return on Investment (Quality Corrected)
� Product Exergy / Processing Exergy = EY/F
W
Wastes
R2
(Odum, 1996; Brown and Ulgiati, 1998; Baral and Bakshi, 2010)
Fuels: Renewability vs. Physical ROI
� Best fuels have high renewability and high ROI
� Bubble area represents fuel use or potential
� �
Renewability
Quality corrected return on investment
Shortcomings of Life Cycle Methods
� Life cycle methods enhance efficiency at large scale
� Focus is on doing “less bad” … not good enough!
� Continuous improvement maintains status quo, does not foster breakthrough innovation
� Ignores capacity of ecosystems to provide services� Ignores capacity of ecosystems to provide services
� Could lead to perverse decisions that increase reliance on degraded ecosystem services
� Cannot benefit from ability of ecosystems to meet industrial and societal needs
Challenges in Sustainable Engineering
� Consider network of processes across scales
� Choose more “eco-efficient” alternative
� Account for role of ecosystem services
� Quantify contribution from nature to human activities
Life Cycle Assessment
� Quantify contribution from nature to human activities
� Account for capacity of ecosystems to provide services
� Exploit synergies between technological and ecological systems to benefit both
Ecologically-Based Life Cycle Assessment
Techno-Ecological Synergy (Eco-Synergy)
Goods and Services from Ecosystems
N, P
Solvents
Pesticides
Sewage
Aromatics Fresh Water
Genetic Resources
WetlandFish, Rice
Flood Regulation
CO2Biomass
Particulate Matter
NOx
CO2
SO2
COO3
O2
Trees & Soil
Pollinators
Fuel
Aesthetics
Recreation
Task Technologicalsystem
Ecological system
Water purification Water treatment Wetland
Air purification Scrubber, precipitator Trees
Carbon sequestration Deep well injection Trees, soil, wetlands
Water provision Dams, canals Forest, aquifers,
Technological vs. Ecological Options
Water provision Dams, canals Forest, aquifers, rivers
Shoreline protection Sea walls Mangroves
Reliable power & flood control
Sediment dredging Forests on slopes upstream of dam
Pollination None Bees, bats, birds
� Are ecological solutions practical and economically feasible?
Renewability vs. ROI with Eco-Synergy
Low Intensity High Diversity grassland• Natural prairie• On degraded farmland
Percent Re
Return on emergy investment
ISSST
Modified Corn• No till• Wetlands• Crop rotation
Eco-Synergy for Biodiesel Production
Conventional Biodiesel Facility
� Eco-efficiency approach will enhance techno-logies to reduce impact
� Ignores local ecosystems
0.4
0.6
0.8
1
1.2
NOx
SOxCO2
0
0.2
0.4 SOx
PM10CO
CO2
Demand for Ecosystem Services
Eco-Synergy for Biodiesel Production
Biodiesel Facility with Eco-Synergy
� Local ecosystems can supply needed ecosystem services
� Highly cost effective & “island of sustainability”
0.4
0.6
0.8
1
1.2
NOx
SOxCO2
0
0.2
0.4 SOx
PM10CO
CO2
Supply of Ecosystem Services with Eco-Synergy
Demand for Ecosystem Services
Columbus Biosolids – Current Approach
� Biosolids coming from two wastewater treatment facilities: Southerly & Jackson Pike
� Allocation between
� Incineration, Landfill, Composting, Land Application
� Minimize cost and carbon dioxide emissions
City of ColumbusWWTP Biosolids
Production
Gravity ThickeningDewatering
Anaerobic Digestion
Decision:How toallocate
biosolids?
Incineration
Landfill
CompostProcess
LandApplication
Ash
LandfillGas
Compost
Fertilizer
10
11
12
Tota
l C
ost
(m
illion
s o
f d
olla
rs)
Base Case
Process Optimization [Sikdar, 2008]
SI - 50%
SL - 5%
SC - 45%
JLA - 9%
JI - 91%
Current Operation
Total CostMillion $
Traditional Engineering Solution
6
7
8
9
0 5000 10000 15000 20000 25000 30000 35000 40000 45000
Tota
l C
ost
(m
illion
s o
f d
olla
rs)
Net GHG Released (tons CO2 equiv)
SI - 100%
JLA - 100%
SI - 41%
SC - 59%
JLA - 100%
SL - 41%
SC - 59%
JLA - 100%
Pareto Curve – no ES or tax
Pareto Curve –no ES,with tax
Designs in this region are not reachable by technological network
Net GHG Released (tons CO2 equivalent)
Biosolids Eco-Synergy
City of ColumbusWWTP Biosolids
Production
Gravity Thickening
Dewatering
Anaerobic Digestion
Decision:How toallocate
biosolids?
Incineration
Landfill
CompostProcess
LandApplication
Ash
LandfillGas
Compost
FertilizerApplication
CarbonTax
Atmosphere
CO2
Decision:How to allocateCO2?
Extend Timber Cycle
New Forest
GeologicalSequestering
Ecosystem
Ecosystem
Underground
Biosolids Eco-Synergy: Problem Formulation
� Multiobjective optimization
� Minimize (Cost, CO2 emissions)
� subject to
� Models of technological systems (incinerator, land fill, land application, composting, geological sequestration)
� Models of ecological systems (forest, timber cycles)
� Carbon tax options
� Determine Pareto curve (win-lose options)
� Choose “best” option by considering all stakeholders
9
10
11
12
Base Case
Process Optimization [Sikdar, 2008]
No Carbon Tax
$15/ton
$30/ton
$50/ton
$75/ton
$100/ton
SL - 41%
SC - 59%
JLA - 100%
Timber - 19%
Forest - 17%
Tax - 64%
SI - 100%
SL - 41%
SC - 59%
JLA - 100%
Timber - 39%
Forest - 26%
Tax - 36%
SI - 50%
SL - 5%
SC - 45%
JLA - 9%
JI - 91%
Current Operation
Total CostMillion $
Biosolids Eco-Synergy: Solution
6
7
8
9
0 5000 10000 15000 20000 25000 30000 35000 40000 45000
Net GHG Released (tons CO2 equiv)
SI - 100%
JLA - 100%
Timber - 14%
Forest - 13%
Tax - 73%
SI - 100%
JLA - 100%
Timber - 29%
Forest - 26%
Tax - 46%
SI - 100%
JLA - 100%
Timber - 29%
Forest - 19%
Tax - 52%
SI - 100%
JLA - 100%
SI - 41%
SC - 59%
JLA - 100%
SL - 41%
SC - 59%
JLA - 100%
Pareto Curve – no tax, no ES
SI - 100%
JLA - 100%
Timber - 41%
Forest - 34%
Geol. - 25%
Zero net CO2
Pareto Curve – with tax, no ES
� Eco-synergy expands design space to allow,
� Identification of new design alternatives
� Closed-loop design within ecological constraints
Conclusions
� Traditional engineering focus on technology and efficiency will not lead to sustainability
� Also true for conventional life cycle approaches
� Need to consider ecosystems
� Compare demand and supply of ecosystem services� Compare demand and supply of ecosystem services
� Include ecosystems in solving design problems
� Techno-Ecological Synergy
� Expands design space by including role of ecosystems
� Enables engineering within ecological constraints
Acknowledgments
� Collaborators� Prof. Gretchen Daily
(Stanford)� Conservation Biology
� Dr. Joseph Fiksel� Corporate sustainability
Prof. Prem Goel
� Graduate Students
� Geof Grubb
� Vikas Khanna
� Shweta Singh
� Bob Urban
Yi Zhang� Prof. Prem Goel� Statistics
� Prof. Bill Mitsch� Ecological engineering
� Post-docs� Dr. Anil Baral
� Dr. Guy Ziv (Stanford)
� Yi Zhang
� Sponsors
� National Science Foundation
� Environmental Protection Agency
� USDA
“Does the educated citizen know he is only a cog in
an ecological mechanism? That if he will work with
that mechanism, his mental wealth and his material
wealth can expand indefinitely? But if he refuses to
work with it, it will ultimately grind him to dust. If
education does not teach us these things, then what is
education for?”
-- Aldo Leopold