Environmental Life Cycle Assessment

PSE 476/WPS 576/WPS 595-005

Lecture 8: Life Cycle Inventory: LCA Stages:

Power and Electricity

Richard Venditti, Jesse Daystar & Carter Reeb

1

Fall 2012

Richard A. Venditti Forest Biomaterials

North Carolina State University Raleigh, NC 27695-8005

Richard_Venditti@ncsu.edu

Go.ncsu.edu/venditti

What is Energy?

• Energy is the potential to do work.

– Potential or Kinetic

• Work = Force * distance

or

• Mass * velocity2

Energy Sources

Non-renewable (Fossil) Fuels

Oil

Natural Gas

Coal

Nuclear

Renewable Fuels

Hydro

Wind

Solar

Biomass

Geothermal

Single (or combined)-cycle Power Generation

• Thermoelectric process

– Combusts coal, natural gas, or oil

– Steam turns turbine

– Rotor turns magnets in generator

– Magnets move past copper wiring – generate electricity

Gas Turbine

• Steam turns gas turbine

Generator

• Stator and Rotor

• Armature and Field windings

Nuclear Power • Uranium fuel rods provide energy

• Heat transfer – steam powers turbine & generator

Hydro-electricity

• Potential energy (head) of water

• Movement past turbine

Photo-voltaic Electricity

• Solar to electricity or,

• Solar thermal concentration to steam production

Biomass Power

• Combustion of biomass (wood)

• Thermal transfer for steam production

• Steam turns generator, creates electricity

• Excess heat captured

• Carbon Neutrality

Electricity Transmission

Electricity Use

Voltage = Current * Resistance Power = Current*Voltage Power used = Current2*Resistance

Voltage is the force moving electrons (potential)

Resistance (or impedance)

Current is the flow of electrons

Demand and Supply of Electricity are balanced !

Why is Electricity transported in high voltage?

• To minimize power losses due to the resistance of the transmitting cables

• Power lost in lines = Current2 * Resistance • To get the power needed to flow through the transmission

lines the Current or the Voltage can be raised, – Power Required= Current * Voltage – Current = Power Required / Voltage

• Power lost in lines = (Power Required/Voltage) 2 *Resistance

Voltage = Current * Resistance Power = Current*Voltage Power used = Current2*Resistance

Why is Electricity transported in high voltage?

Voltage = Current * Resistance Power = Current*Voltage Power used = Current2*Resistance

• Power lost in lines = (Power Required/Voltage) 2 *Resistance • If you reduce the Voltage used by one-tenth, the losses will be reduced

by one-hundredth • (Also, higher voltage allows for thinner cables to be used. Also, voltage

is the potential that is required to move the electricity.)

• Transmission lines: 110,000-120,000 Volts or 110-120 kV

• A few transmission lines have been designed at 1.2 million volts !!

Electricity Balance • The production and demand must be balanced, always • Base load are satisfied typically with large efficient plants • Spinning reserve, comes on only during peak times, lowere efficiency

power sources, • Intermittent energy sources, suffer because they cause problems with

balancing supply and demand __________________________

Total electricity consumption in CA on a hot day. http://www.mpoweruk.com/electricity_demand.htm

How to choose?

Price per MJ Fuel Crude Oil $16.03 Natural Gas $2.74 Coal $2.31 Gasoline $24.49 Gasoline $30.83

Electricity Emissions

• Flue-gas desulfurization (FGD) is a set of technologies used to remove sulfur dioxide (SO2) from exhaust flue gases of fossil-fuel power plants.

Electricity Emissions • Careful, parts thinking, this is only

one aspect of the entire issue

• Other issues:

Emissions Factors for LCA

Emissions Factors for LCA Combustion Pre-combustion Total

kg CO2 eq/GJ

HHV

kg CO2 eq/GJ

HHV

kg CO2 eq/GJ

HHV

Anthracite coal 94.05 24.464 118.514

Bituminous coal 90.32 5.382 95.702

Diesel 70.59 12.256 82.846

Distillate fuel oil (#2 fuel oil) 70.59 12.256 82.846

Gasoline 66.08 11.823 77.903

Kerosene 68.55 11.862 80.412

Lignite 96.61 10.56 107.17

Natural gas 50.54 12.784 63.324

Non-recyclable paper 0 0 0

Other No default No default No default

Other biomass 0 No default No default

Petroleum coke 92.87 18.712 111.582

Propane (LPG) 60 11.865 71.865

Purchased hogged fuel, from logging residues 1.84 0.19 2.03

Purchased hogged fuel, from manufacturing residues 1.84 3.081 4.921

Purchased spent liquor solids 0.637 0 0.637

Residual fuel oil (#5, #6) 73.77 12.331 86.101

Self-generated hogged fuel, from logging residues 1.84 0 1.84

Self-generated hogged fuel, from manufacturing residues 1.84 0 1.84

Self-generated spent liquor solids 0.637 0 0.637

Sawdust 1.84 3.081 4.921

Tire derived fuel 81.49 0 81.49

Fuels inputs

Most emission Factors are Tier 1 from Revised 2006 IPCC Guidelines for National Greenhouse Gas Inventories: Volume 2 Energy, Chapter 2 Stationary Combustion (unless noted otherwise) Converted from LHV basis to HHV by multiplying by 0.95 (or 0.9 in the case of natural gas)

What is biomass? • Using sunlight and photosynthesis, plants convert

atmospheric CO2 into plant tissue (biomass) and stored energy (Source: NCASI)

Photosynthesis

CO2 + sunlight =

biomass + stored energy

CO2

Carbon in atmospheric CO2 becomes carbon in biomass

(biogenic carbon)

The chemical bonds in biomass store the sun’s energy

The Biomass Carbon Cycle

• Biogenic carbon is part of a relatively rapid natural cycle that impacts atmospheric CO2 only if the cycle is out of balance

Atmosphere

Biomass

(Biogenic)

Carbon B

iog

enic

CO

2

CO

2

CO2 CO2

Is the biomass carbon cycle in balance?

U.S. Global B

iogenic

CO

2

CO

2

Bio

genic

CO

2

CO

2

Increases in atmospheric CO2 caused by deforestation, primarily in the tropics, are being offset by

growth in global forests. The exact balance is uncertain.

Removals of CO2 from the atmosphere by U.S. forests are larger than releases of biogenic CO2. The difference (a net uptake of CO2) offsets approximately

10% to 15% of all U.S. GHG emissions.

Balance uncertain

Balance favorable

Using the forest biomass carbon cycle to avoid fossil fuel CO2 emissions

Atmosphere

Biomass Carbon

Bio

gen

ic C

O2

CO

2

Energy (and biomass-based products) can be produced as carbon moves through the biogenic

carbon cycle.

Fossil

Fuel

Atmosphere

Non

-bio

genic

CO

2

Biomass energy and products can displace those made from fossil fuel,

avoiding fossil fuel CO2 emissions.

Biomass Energy

Energy

How does the use of biomass impact atmospheric CO2?

• Biogenic CO2 was only recently removed from the atmosphere, so returning it to the atmosphere merely closes a cycle

• Nonetheless, the use of biomass can impact atmospheric GHGs – If it causes the biomass carbon cycle to be out of balance

– If other GHGs are released in various stages of the life cycle

– If other uses of biomass give us larger or smaller benefits

How does the use of biomass impact atmospheric CO2?

2. If other GHGs are released in the life cycle (Remember avoid parts thinking)

Atmosphere

Bio

genic

CO

2

CO

2

Biomass Energy

Products

Biomass

Biomass

Carbon

Foss

il fu

el

Foss

il fu

el

Fert

ilize

rs

Foss

il C

O2

Foss

il C

O2

Oth

er

GH

Gs

Oth

er

GH

Gs

Oth

er G

HG

s

Foss

il fu

el

Foss

il C

O2

Other than atmospheric CO2?

• Biomass and biofuels have other environmental/social/economic impacts other than emissions

• Example: land use change

• Example: eutrophication from fertilizers

Environmental impacts of cellulosic ethanol in the Southern U.S. using a thermochemical conversion pathway

(in preparation)

Jesse Daystar, Carter Reeb, Ronalds Gonzalez, Richard Venditti

Bioethanol from Cellulosic Biomass

• System boundary for the life cycle assessment of bioethanol from cradle-to-grave; assuming thermochemical conversion of the biomass to ethanol and use in a light-duty transport vehicle.

Bioethanol from Cellulosic Biomass

• Direct land use change impacts on net GHG emissions of 1 MJ ethanol. (IPCC and FICAT data used for land use change)

• Normalized environmental impacts of cellulosic ethanol and gasoline using the TRACI impact assessment method, bars left to right correspond to legend left to right and top to bottom

0.

10.

20.

30.

40.

50.

60.

70.

80.

90.

100.

GlobalWarming

Acidification Carcinogenics Noncarcinogenics

Respiratoryeffects

Eutrophication Ozonedepletion

Ecotoxicity Smog

%

Loblolly Pine Eucalpytus Unmanaged Hardwood

Forest Residues Forest Residues no burden Switchgrass

Gasoline

• Environmental impacts normalized to the impacts of a European over a year, Eco-indicator

Summary of Bioethanol Study

• Significant reduction with TC Cellulosic Bioethanol in GHG compared to gasoline

• Land use changes significant

• Differences in biomass

• Other environmental impacts of the bioethanol exist, especially for switchgrass

Primarily Hydro-electric

Primarily Coal and Nuclear

Primarily Coal

Electricity: Regionalized Emissions

Combustion related

emissions

Precombustion

emissions*Total

North America 651.1 17 668.1

U.S. 705.5 18.1 723.6

Eastern Inter 729.3 18.6 747.9

Western Inter 568.0 15.3 583.3

New England 499.7 13.8 513.5

Mid Atlantic 548.4 14.8 563.2

East-North Central 755.7 19.2 774.9

West-North Central 568.0 15.3 583.3

South Atlantic 754.6 19.2 773.8

East-South Central 793.9 20 813.9

West-South Central 771.2 19.5 790.7

Mountain 847.4 21.1 868.5

Pacific Contiguous 308.2 9.7 317.9

Pacific Non-Contiguous 723.80 18.50 742.30

Region

kg CO2 eq./MWh electricity

Reference for electricity grid (2006 data):

US, grid mixes:

http://www.eia.doe.gov/cneaf/electricity/epa/epa_sprdshts.html

Electricity: Regionalized Emissions

Reference for electricity grid (2006 data):

US, grid mixes:

http://www.eia.doe.gov/cneaf/electricity/epa/epa_sprdshts.html

Combustion related

emissions

Precombustion

emissions*Total

Region

kg CO2 eq./MWh electricity

North Carolina 686.6 17.7 704.3

North Dakota 1022.0 24.8 1046.8

Nebraska 732.7 18.7 751.4

New Hampshire 429.9 12.3 442.2

New Jersey 396.5 11.6 408.1

New Mexico 989.1 24.2 1013.3

Nevada 749.6 19.0 768.6

New York 426.2 12.2 438.4

Ohio 957.6 23.5 981.1

Oklahoma 882.8 21.8 904.6

Oregon 208.3 7.6 215.9

Pennsylvania 669.9 17.4 687.3

Rhode Island 719.1 18.4 737.5

South Carolina 475.9 13.3 489.2

Electricity: Regionalized Emissions

Combustion related

emissions

Precombustion

emissions*Total

Region

kg CO2 eq./MWh electricity

Canada 205.4 8.3 213.7

Alberta 925.6 24.5 950.1

British Colombia 17.0 4.5 21.5

Manitoba 11.2 3.6 14.8

New Brunswick 366.4 13.3 379.7

Newfoundland/Labrador 15.1 3.8 18.9

Nova Scotia 548.7 19.3 568.0

Ontario 183.9 8.2 192.1

Prince Edward Island 192.3 3.9 196.2

Quebec 6.0 3.4 9.40

Saskatchewan 811.4 19.4 830.8

Yukon, Norwest Terr. & Nunavut 84.3 10.3 94.6

Environment Canada. 2008. National Inventory Report 1990 -2006: Greenhouse Gas Sources and Sinks in Canada. Gatineau, Qc: Environment Canada.

Summary

• Non-renewable fuels • Renewable fuels • Thermoelectric Process • Electricity Balance • Base load • Spinning reserve • Intermittent energy sources • Biomass carbon cycle • Displacement • Regionalized electricity emissions

References

• Dr. Eccles, Duke University

• http://www.eumayors.eu/IMG/pdf/technical_annex_en.pdf

• http://www.worldenergy.org/documents/lca2.pdf

Questions?