Alternative Energy

Justin Borevitz 1/10/07

Just drill in the Artic

Just gasify coal

Just put CO2 underground

Just buy a hybrid“I’m done”

Just use methane

Nuclear

Just invade IranJust invaded Somalia

Just let it happenI like it warm

do polar bears?

More corn for ethanolI like to eat corn anyhow

The Energy Problem

• How will society meet growing energy demands in a sustainable manner?

• Fossil-fuels currently supply ~80% of world energy demand.

Are Biofuels the Answer?...

Biofuels as an Alternative

• Biofuels are not THE answer to sustainable energy, but biofuels may be part of the answer

• Biofuels may offer advantages over fossil fuels, but the magnitude of these advantages depends on how a biofuel crop is grown and converted into a usable fuel

Analysis of Alternative Biofuels

• “First generation” biofuels: food-based biofuels that are currently commercially available:– Corn-grain ethanol– Soy Biodiesel

• “Second generation” biofuels: cellulosic biofuels of the future– Diverse prairie biomass

Biofuels.. Renewable/sustainable?

• Fossil fuel subsidy?

• Soil fertility subsidy?

• Water subsidy?

• Land use subsidy?

• Biodiversity/ecological subsidy?

• Farmer subsidy?

• Civil/ social subsidy?

Biofuels.. Carbon neutral?

• Fossil fuel subsidy?– Fertilizer, pesticide, plant, harvest, process

• Soil fertility source or sink?• Land use

– from conservation (eg rainforest), CO2 sinks– from food production

• Carbon cost processing• Investment in time• Investment in $$

Biofuels saves us

• Corn based ethanol subsidized at $0.51 on the dollar

• Corn for corn $0.50 on the dollar

• $500M DOE research funding

• All arable US land to ethanol, 1/3 of foreign oil. Food?

• Iowa $1B in 4 ethanol distillers

Evolution of Ecosystems

• Niche colonization, spatial temporal

• Synergistic interactions among kingdoms

• Local and regional adaptation, within and between species

Prairie disturbance

• Large herbivores

• Early Man/woman’s fire

• Colonial man’s plow,

• Now industrial man’s intensive agriculture

• Next post industrial man/woman’s harvest of biomass?

C4 and C3 grasses

• Plant Physiology

• How would both help?– cool season warm season

How Much Do They Supply?

• Corn grain ethanol (2005):– 14.3% of the US corn harvest was used to

produce 1.48x1010 L of ethanol annually– Energetically equivalent to 1.72% of US

gasoline use

• Soy biodiesel (2005)– 1.5% of the US soybean harvest produced

2.56x108 L of biodiesel annually– 0.09% of US diesel use

But How Much Could They Supply?

• Devoting all US corn and soybean production to biodiesel and ethanol would generate:– 12% of US gasoline consumption– 6% of US diesel consumption

• In terms of net energy gain: – 2.4% of US gasoline consumption– 2.9% of US diesel consumption

Food vs. Fuel: Impact on Corn Prices

Average corn grain yield and NO3-N concentration in soil water at 7.5 feet in Nov. 1992 as influenced by nitrogen rates from 1987-91 for corn in Olmsted Co.

(From Randall et al.).

1987-91 rate (lb N/A per yr)

1987-91 Avg. Grain Yield (bu/A)

NO3-N Concentration in soil water at 7.5 feet (ppm)

0 82 2

75 141 4

150 168 17

225 164 32

Ethanol Demand and Corn Prices

• Large increase in demand for corn for ethanol production– Production capacity over 5 billion gallons– Projected to increase to over 9 billion gallons

with current plants under construction

• Corn prices in January 2007 topped $4/bushel

• Price has doubled since early 2006

Are Biofuels Cost Competitive?

• In 2005, neither biofuel was cost-competitive with petroleum – but as petroleum prices increased the gap closed

• Ethanol:– Estimated ethanol production cost in 2005 was $0.46 per

gasoline energy equivalent L– Wholesale gasoline prices averaged $0.44/L in 2005

• Soy biodiesel– Estimated soybean biodiesel production cost in 2005 was $0.55

per diesel EEL, – Diesel wholesale prices averaged $0.46/L in 2005

• Recent price effects unfavorable for biofuels:– Lower fossil-fuel prices– Higher corn prices

Summary

• Corn grain ethanol and soy biodiesel can make up only a small portion of fuel supply

• Subsidize environmentally friendly biofuels– Subsidy for corn grain ethanol does not

appear justified – Subsidy for soy biodiesel may be justified

• Should look to other sources

Second Generation Biofuels: Cellulosic Feedstock…

Switchgrass Wheat Straw Hybrid Poplar Corn StalksSwitchgrass Wheat Straw Hybrid Poplar Corn Stalks

University of Minnesota Initiative for Renewable Energy and the

Environment

Hydrogen Bio-basedMaterials

Ecosystems Conservation Economicanalysis

Policy

Research Clusters Demonstration Clusterse.g. Morris project

Renewable Energy & the Environment

Fermentor:The workhorse

• Bio-based methods for – Materials– Energy

The Next Generation of Biofuels:The Next Generation of Biofuels:Greenhouse-Neutral Biofuels from Greenhouse-Neutral Biofuels from

High-Diversity Low-Input High-Diversity Low-Input Prairie EcosystemsPrairie Ecosystems

bybyDavid TilmanDavid Tilman

University of MinnesotaUniversity of Minnesota

Learning from Current Biofuels: Ethanol from Corn and Biodiesel from Soybeans

legumes

• Symbiotic relationship with rhizobium bacteria to fix nitrogen,– even Word knows this “a soil bacterium that

forms nodules on the roots of legumes such as beans and clover and takes up nitrogen from the atmosphere. Genus: Rhizobium”

• Species Functional type• Lupinis perennis Legume• Andropogon gerardi C4 grass• Schizachyrium scoparium C4 grass• Sorghastrum nutans C4 grass• Solidago rigida Forb• Amorpha canescens Woody legume• Lespedeza capitata Legume• Poa pratensis C3 grass• Petalostemum purpureum Legume• Monarda fistulosa Forb• Achillea millefolium Forb• Panicum virgatum switchgrass! C4 grass• Liatris aspera Forb• Quercus macrocarpa Woody• Koeleria cristata C3 grass• Quercus elipsoidalis Woody• Elymus canadensis C3 grass• Agropyron smithii C3 grass

Low Input High

Diversity

Experimental Design

• Been running since 1994• 168 - 9m x 9m plots, in 1 location in Minnesota• 1, 2, 4, 8, or 16 perennial grassland/ savanna species.• from a set of 18 perennials: 4 C4, 4 C3 grasses, 3

herbaceous and 1 woody/shrubby legume, 4 non-legume herbaceous forbs, and 2 oak species

• Watered initially, weeded 3-4 times (to maintain low diversity, like a crop), burned each Spring (which killed the woody species, or plots were left (152 plots) out as not measures of annual biomass)

Net Energy Balance of Corn Ethanol and Soybean Biodiesel

Environmental effects…

• Fertilizer use • Pesticide application

Environmental effects of ethanol and biodiesel

Greenhouse gasses

reduced by both relative to

gasoline and diesel

combustion

Current and Maximal Potential Production of Food-Based Biofuels:

Current US BiofuelCurrent US Biofuel

Production (2005)Production (2005)

Devoting entire US Devoting entire US crop production to crop production to

biofuelbiofuel

Corn grain ethanolCorn grain ethanol1.7% of gasoline usage1.7% of gasoline usage

14% of corn harvest14% of corn harvest

12.0% of gasoline usage12.0% of gasoline usage

100% of corn harvest100% of corn harvest

2.4% Net Energy Gain2.4% Net Energy Gain

Soybean biodieselSoybean biodiesel0.1% of diesel usage0.1% of diesel usage

1.5% of soybean harvest1.5% of soybean harvest

6.0% of diesel usage6.0% of diesel usage

100% of soybean 100% of soybean harvestharvest

2.9% Net Energy Gain2.9% Net Energy Gain

Toward better biofuels:

1) Biomass feedstock producible with low inputs (e.g., fuel, fertilizers, and pesticides)

2) Producible on land with low agricultural value

3) Conversion of feedstock into biofuels should require low net energy inputs

The Cedar Creek Biodiversity Experiment

Established to study the fundamental impacts of biological diversity on ecosystem

functioning

352 Plots9 m x 9 m

Random Compositions1, 2, 4, 8, or 16 SpeciesPlus, 70 Plots with 32

Species(1994-Present)

High Diversity Grasslands Produce 238%

More Biofuel Each Year Than Monocultures

Switchgrass

Current and future biofuels

Ethanol Production

Corn Production

Seed

Fertilizer (N, P, K)

Herbicides, Pesticides

Production Energy (Diesel, Electricity, etc.)

Producer Household Energy Consumption

Farming Methods

Irrigation

Land Use (Opportunity Cost)

Water Impacts

Soil Impacts

Energy Inputs (Electricity, Natural

Gas, Steam, etc.)

Erosion

Nutrient Depletion

Contamination

Sedimentation

Nutrient Loading

Production Inputs (Enzymes, Yeast,

Ammonia, Urea, Sulfuric Acid, Water, etc.)

Co-generation (Steam, Heat)

Ethanol

Distillers Dry Grain

Wastewater

Air Emissions (VOx, particulates)

Gas (5% by volume)

Aesthetic Costs (odor, etc.)

Recreation, Aesthetics

CO2 Capture

Combustion Emissions

Storage and Distribution

Full cost accounting for Corn EtOH

Use of full cost accounting

• To compare alternative energy sources, we should consider the full costs not just the direct costs

• Energy sources that have lowest full cost to produce a unit of energy are the most desirable (i.e., greatest net benefit)

• Challenge: estimating major external costs for alternative sources of energy

Importance of inclusion of external costs

• Including external costs makes any particular energy source look less attractive

• What is of importance is not cost estimate of any particular source, but the comparison across sources

• Not including external costs unfairly penalizes renewable sources of energy because of the generally high external costs of fossil-fuel use

Diverse Prairies Remove & Store Carbon

Diverse plots store C in Roots

Diverse plots store more C in Soil

High-DiversityPrairie Biofuels

Are CarbonNegative

3.3 t/ha C Storage0.3 t/ha Fossil C

Net Storage of 3.0 t/ha of CO2

Less CO2 in Atmosphere

After Fuel Growth And Use than Before

LIHD: Potential Global Effects?May Meet 15% to 20% of

Global Electricity & Trans. Fuel DemandGreenhouse Gas Impact per Hectare: 2.3 t ha yr-1 of C net displacement of fossil fuel by biomass+ 1.1 t ha yr-1 of C sequestration in soil and roots= 3.4 t ha yr-1 total net reduction in atmosphere C loading

Degraded Land Base:(51.0 x 108 ha globally of agricultural land) 0.7 x 108 ha abandoned - US+ 1.2 x 108 ha abandoned - other OEDC nations+ 3.0 x 108 in non-OEDC nations= 4.9 x 108 current total agric degraded land

3.4 t ha yr-1 x 4.9 x 108 ha = 1.7 x 109 t/yr reduction in C (as CO2) input into atmosphere

Potential of a 24% Reduction in CO2 Emissions

Low-Input High-Diversity Biofuels

• Can be produced on degraded agricultural lands, sparing native ecosystems & food production

• Negative net CO2 emissions (carbon sinks)

• Highly sustainable and stable fuel supply• Cleaner rivers and groundwater• More energy per acre than food-based

biofuels

Fig. 1. Effects of plant diversity on biomass energy yield and CO2 sequestration for low-input perennial grasslands. (A) Gross energy content of harvested above ground biomass (2003–2005 plot averages) increases with plant species number. (B) Ratio of

mean biomass energy production of 16-species (LIHD) treatment to means of each lower diversity treatment. Diverse plots became increasingly more productive over time. (C) Annual net increase in soil organic carbon (expressed as mass of CO2 sequestered in upper 60 cm of soil) increases with plant diversity as does (D) annual net sequestration of atmospheric carbon (as mass of CO2) in

roots of perennial plant species. Solid curved lines are log fits; dashed curved lines give 95% confidence intervals for these fits. [View Larger Version of this Image (156K JPEG file)]

 

Fig. 2. NEB for two food-based biofuels (current biofuels) grown on fertile soils and for LIHD biofuels from agriculturally degraded soil. NEB is the sum of all energy outputs (including coproducts) minus the sum of fossil energy inputs. NEB ratio is the sum of energy outputs divided by the sum of fossil energy inputs. Estimates for corn grain ethanol and soybean biodiesel are from (14).

Fig. 3. Environmental effects of bioenergy sources. (A) GHG reduction for complete life cycles from biofuel production through combustion, representing reduction relative to emissions from combustion of fossil fuels for which a biofuel substitutes. (B) Fertilizer and (C) pesticide application rates are U.S. averages for corn and soybeans (29). For LIHD biomass, application rates are based on analyses of table S2 (10).

* We assume that producing seed for planting prairies requires twice the energy used to produce prairie biomass, and that two or three hectares can be planted from the seeds harvested from each hectare of degraded or fertile prairie, respectively. We divide this total energy input over an assumed 30 year life of the prairie. † We assume 30.5 L ha-1 of diesel are used in the first year for spraying, disking, planting, and mowing (S16), and that diesel releases 36.6 MJ L-1. We distribute this total energy input over a 30 year life of the prairie. Annual fuel use for mowing, baling, an`d fertilizing is 13.8 L ha-1.‡We estimate the weight of equipment used in production (i.e., boom sprayer, tandem disk, notill drill, rotary mower/conditioner, hay merger, large rectangular baler, 75 hp tractor, 130 hptractor, pull spreader, loader, and bale spike) to be 3.6 × 104 kg. We assume for purposes of calculating the embodied energy of each piece of machinery that it consist entirely of steel and that it takes 25 MJ kg-1 to produce steel (S17, S18) with an additional 50% for assembly (S19).We distribute this over a 30 year life of the prairie and a 240 ha size of the farm.§We assume a first year 2.24 kg ha-1 application rate of glyphosate, which requires 475 MJ/kg to produce and distribute (S20). We divide this energy input over an assumed 30 year life of theprairie. We assume phosphorus fertilizer, which takes 9.2 MJ/kg to produce and transport (S21), is applied every three years at a rate of 7.4 kg ha-1 yr-1 on degraded prairie and 12.0 kgha-1 yr-1 on fertile prairie to replace phosphorus removed in harvested biomass. || The 2004 U.S. per capita energy use was 3.58 × 105 MJ (S22, S23). We assume household size of 2.5 people (S24), 50% of farm household labor devoted to farming (S25), and a 240 ha farm.¶ We estimate 24 and 38 L ha-1 of diesel is used to move bales onto and off of tractor trailers for degraded and fertile prairies, respectively (S16). We assume bales weigh 680 kg, each tractor trailer can haul 27 bales, and bales are transported an average of 40 km to their point of end use. With an average fleet efficiency of 2.2 km/L (S26), 36.4 L of diesel are used in a single round trip to haul the bales produced on 4.9 ha of degraded prairie or 3.0 ha of fertile prairie.

* Although we have data on biomass production on fertile soils for prairie, we do not have comparable data on LIHD carbon storage in such soils, and thus do not present this case in this table.† Values are from (S27).‡ This includes diesel used for producing prairie seed, planting and harvesting, and transporting bales. Diesel life cycle GHG emissions are 3.01 × 103 g CO2 eq. L-1 (S28). We also include GHG release in pesticide production, sustaining farm households, and producing farm capital and machinery by assuming they require use of an amount of diesel equivalent to the energy expenditure of these inputs.

§This value is the amount of fossil fuels each use of biomass displaces (energy equivalent) multiplied by the life cycle GHG emissions of the displaced fossil fuels. We assume ethanol displaces gasoline (life cycle GHG emission = 96.9 g CO2 eq. MJ-1) (S28), biomass-generated electricity displaces coal-generated electricity (life cycle GHG emission = 289.5 g CO2 eq. MJ-1) (S29), and synfuel displaces 38% gasoline and 62% diesel (life cycle GHG emission = 82.3 g CO2 eq. MJ-1) (S14, S28).

Burgeoning real estate market in Greenland

Final Thought

• “Agriculturalists are the de facto managers of the most productive lands on Earth. Sustainable agriculture will require that society appropriately rewards ranchers, farmers and other agriculturalists for the production of both food and ecosystem services.” (Tilman et al. Nature 2003)