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Horacio Aguirre

on 21 April 2014

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Transcript of Sustainability

photo credit Nasa / Goddard Space Flight Center / Reto Stöckli
Challenges of environmental sustainability
appetite and intensity
are increasing globally

1.2 billion people still lack electricity
Energy consumption is expected to rise 56% by 2040

Most energy comes from fossil fuels

Fossil fuels are limited and diminishing
and the major contributors to climate change
Land Use and the Nutrient Cycle
There is a
finite amount of arable land
and freshwater to produce food crops and livestock on our planet

Intensive agriculture makes even the richest soil to rapidly
lose nutrients, some of which are finite

To make up for this loses, over application of nitrogen and the
nitrogen cycle
has become a major challenge to scientists
Anthropogenic GHGs
(caused by human activities)
GHG emissions are expected to
increase 2% annually
between 2001 and 2025

Energy production the major contributor to total GHGs, but
agriculture is the major methane (CH4) and nitrous oxide (N2O)
Dairy accounts for 30%
of agriculture GHGs

Characterization factors:
1 kg CO2 = 1 kg CO2-eq
1 kg CH4 = 25 kg CO2-eq
1 kg N2O = 298 kg CO2-eq
Climate Change
Evidence of global warming:
Rising temperatures of the earth's surface and sea level
More extreme weather events (droughts, tornadoes, floods)
Sea level rise, coastal erosion.

Global warming is caused by
greenhouse gases (GHG)
that rise into the atmosphere, trap the sun's energy and keep heat from escaping
Amount of land needed to offset total GHG emissions caused by the average individual
How Many Earths?
Depletion of Energy Resources
World Energy Consumption (1830-2010)
Waste and Water Quality
The average person generates
1.9 kg of waste per day
(60% increase in the last 50 years)

Waste management demands
energy and land
resources and emits GHGs

Agricultural waste (i.e. animal manure)
is usually land spread, which result in further challenges due to eutrophication of water streams
How can we evaluate environmental sustainability?
Life-cycle assessment (LCA)
is the compilation and evaluation of the inputs, outputs, and potential environmental impacts of a product, service, or system throughout its life cycle

Initially used in product campaigns
Main method to quantify environmental impacts in the bio-energy world (RFS-EISA and LCFS)

How far upstream and downstream do we want to go?
System Boundaries
Functional unit: i.e. one object, yearly production, daily production, etc.
Define sustainability indicators (i.e. greenhouse gases, depletion of fossil fuels)
Research every input/output within your system boundaries
Sensitivity analysis

My Research: Integrating Agricultural and Bio-energy Systems
Dairy herd
Crop production
Corn ethanol and soybean biodiesel
Milk processing
Biofuels achieve
climate change and energy security
But pose
additional concerns
: food crops, take high productive land

Wisconsin is America's dairy land,
But besides milk the 1.2M dairy cows produce nearly
26M wet tons manure per year
(65 kg manure per cow per day)
Final use and disposal
Manure Management
Processing at dairy plant
Cheese, whey, etc
Dairy products
DDGs and Soybean meal
Fuels and energy
Embedded material and energy inputs
The Greencheese model
Keeping Track of Carbon
Global warming potential of different diets according to farm processes
Environmental impacts of integrated dairy and bio-fuels production
My research explores ways to
integrate biofuels with current agricultural systems
rather than compete with them
Develop agricultural lifecycle inventory data
Quantify sustainability indicators
Identify and compare environmental trade-offs to prioritize improvement strategies

Provide guidance
Individual farms
choosing more sustainable technologies and management practices
Policy makers
aiming at better resource allocation
Prepare for
carbon credits
Process based
LCA: representing biological relations with mathematical equations


Survey: manure management practices
Laboratory experiments
Literature review
State databases (i.e. temperature, crop production)

Electricity matrix of WI
(55% coal, 19% natural gas, 20% nuclear, 2% hydro, 2% wind, 1.5 biomass, 0.2% solar)

biotic emissions from fossil emissions
Scientists from: Dairy sciences, biological systems engineering, soil sciences, animal sciences
GHGs, energy intensity, and land use are quantified and compared
5 diets are compared with different DDGS and SBM concentrations (without affecting milk quality)

All values are presented in relation to diet CADS (100%)
More DDGS = less GHG and lower net energy intensity but more land are used
Producing 1 kg of milk emits 0.8 to 0.9 kg CO2-eq
Enteric methane is the major contributor to GWP followed by manure management

4 manure processing pathways
Surface broadcast (base-case: BC)
Solid-liquid separation (SLS)
Anaerobic digestion (AD)

Sustainability indicators:
NH3 emissions
Primary fossil energy consumption

Anaerobic digestion:
microorganisms break down biodegradable material in the absence of oxygen.
System Boundaries
Help current dairy farmers to adopt new technologies and management practices according to their priorities and needs

Provide information for existing policy frameworks, or guidelines for new climate and energy policies

Addressing climate change while providing sustainable energy and processing agricultural waste

Replication and scalability

Environmental Impacts and Sustainability of Integrating Agricultural an Bio-energy Systems
Horacio Aguirre-Villegas

Ph.D. candidate
Biological Systems Engineering
Thank You
Nitrogen Cycle
Why Wisconsin?
Full transcript