Example of Small LCA Project

1. Example of Small LCA Project

2. Steps of an LCA

3. Goal Definition and Scope • Evaluate burning firewood in residential application as a supplement to fossil • House is in Kentucky and current heating is with an air source heat pump and natural gas furnace • Determine impact of current fossil fuel consumption with supplemental wood heat

4. Scope Continued • Consider impact of power plant and combustion of nat gas in house • Harvest and transport of firewood from Berea • Impacts considered • CO2 • NOx • SOx • Particulate matter (PM) • Costs

5. Inventory Analysis - Procedure • Obtained previous years utility bills • Picked lowest month and used that bill as baseload electrical/gas consumption • Estimated fuel consumption for chainsaw and log splitter • Estimated quantity and energy value of firewood

6. Existing Appliance Performance • Air source heat pump • COP at 47F is 3.6, COP at 17F is 2.5 • Assume average of 3.0 • Actually two heat pumps in house, assume both are same (similar performance) • Gas furnace is 80% AFUE • Use on a seasonal heating basis • 4600 kWh of electricity (15.7 million Btu) • 31.4 MCF (31.4 million Btu) • We need 76.2 GJ/heating season in the house

7. Emissions from Fossil • Natural gas appliances in residential applications – DOE EERE (2008 standards) • Emissions from power plants DOE – EIA KY electric profile (2009) • PM from coal combustion NREL (1999)

8. Wood Burning Characteristics • Energy content from University of MO for hackberry (21.6 million btu/cord) • Estimated 2.5 cords of firewood (5 pickup loads) • Emissions from fireplace – EPA certified stoves • 36,000 btu/hr output at 63% efficient • 4.42 g PM/hr • Other emissions (NOx and SOX) from 1999 EPA document (g/kg basis)

9. Wood Harvest • EPA standards for SI gasoline engines under 18 hp (Federal Register for 2000) • Assume engines are 33% efficient – no reference • Emissions listed for • CO (assume all goes to CO2) • HC+NOx (from EPA, 2/3 of this category would go to PM, assume this is true, based on cars) • Gasoline 340 ppm sulfur – assume goes to 2.78 g SO2/gallon

10. Results – Impact Assessment • Emission factors (fossil and wood burning) • Total emissions for house (fossil and wood burning)

11. Results – Emission Factors Considers upstream emissions

12. Results – Emissions from Original

13. Results – Emissions with Stove

14. Results Net Changes

15. Interpretation - Existing • Air source heat pump reduces impact due to COP • Use half the energy of natural gas • Get over 2/3 of useful heat from electricity • Natural gas high NOx emissions • Coal has high CO2, SOx, and PM

16. Interpretation - Wood • 45% reduction in fossil energy • Assumed evenly split between gas/electric • Significant reduction in CO2 and SOx relative to base case • PM slightly lower than base • NOx increased relative to base case • Small SI engines big part of NOx emissions

17. Impact of Various Stages

18. Summary of Impacts

19. Life Cycle Costing • $661/yr in heating for fossil case • With wood stove increases to $759/yr • Due to cap cost of stove (~400/yr) • Would take a 40% increase in electric and nat. gas cost to be equal • No value on time handling firewood

20. Potential Problems • Uncertainty in electricity used for heating – based on lowest electric bill • Assumed a SI engine efficiency • Assumed conversion of HC to PM • Other conversions from g C to g CO2 and g S to g SO2 • Splitting of energy reduction – assumed equal gas and electric

21. Other Potential Problems • Wife not happy with me gutting the fireplace and redoing it according to manufacturer’s specs • Estimates on fuel consumption during wood cutting • Happy cat though