Maine’s GHG Inventory, 1990-2000

1. Maine’s GHG Inventory, 1990-2000 Prepared by the Maine DEP November 6th, 2003

2. What is an Emissions Inventory ? • Comprehensive list by source, of air pollutant emissions • Covers a specific geographic area • Over a specific time interval

3. What is an Emissions Inventory ? Cont. • Type of emissions sources • Point Source - individual sources of emissions • Area Source - aggregate of small sources • Mobile Source - cars, trucks and others

4. What is an Emissions Inventory ? Cont. • Approaches to inventories • Top Down - Based on national or regional estimates for similar types of emissions sources • Bottom Up - Source specific information • Note - Top down inventories are less resource intensive; however the resource savings comes at a cost to the precision of the inventory.

5. What is an Emissions Inventory ? Cont. • Emission Inventories are estimates of emissions

6. Why do a GHG Emissions Inventory ? • Identify sources of GHGs • Quantify sources of GHGs • Develop strategies to control GHGs • Assess effectiveness of the strategies

7. GHG Emissions Source Sectors • Transportation • Mobile on-road and non- road emissions • Waste • Solid waste disposal (landfills, combustion) • Waste water treatment plants • LUCF • Land use change and forestry practices (may be a net source or sink)

8. GHG Source Sectors Cont. • Residential • Home heating • Industrial • Space heating at industrial facilities • Commercial • Heating in retail and office space

9. GHG Source Sectors Cont. • Industrial Process • Manufacturing process emissions • Cement and Semi-conductors • Electric Utilities • Power plants and Co-generation facilities • Agriculture • Enteric Fermentation, Manure Management • Agriculture Soil Management

10. Greenhouse Gases • Carbon dioxide (CO2) • Methane (CH4) • Nitrous oxide (N2O) • Hydrofluorocarbons (HFCs) • Perfluorocarbons (PFCs) • Sulfur Hexafluoride (SF6)

11. Units of Measure • Non-CO2 gases converted to CO2 equivalents using agreed Global Warming Potential (GWP) values • Total inventories generally measured in million metric tons of carbon equivalent or CO2 equivalent -- check units when comparing inventories

12. Guidance Materials for Inventories • Basic ground rules developed and updated by Intergovernmental Panel on Climate Change for Annex I parties to FCCC • EPA sets guidance for U.S. national inventory and for states, based on international practices with modifications where appropriate for U.S. • Trade Association may supply guidance • Other entities (World Resources Inst. (WRI))

13. Guidance Materials, cont. • Guidance may change periodically • New data becomes available • Scientific understanding of GHGs improves • Refinements in emissions factors

14. State GHG Inventory Tool • Developed for EPA, by a contractor, to make the inventory process less time- and resource-intensive and to make state inventories more comparable in terms of data and methods • Provides state-specific default data from Federal sources in spreadsheet form; states can use defaults or insert their own data • Default data use represents a Top Down inventory approach.

15. Uncertainty Associated with Estimating GHG Emissions • GHGs are rarely measured directly ; emissions are more typically calculated on the basis of emissions factors, or are inferred on the basis of observed relationships. • Precision of input data varies widely • fuel usage at power plants vs. waste placed in landfills • proprietary processes maybe reported with less precision

16. ME GHG Emissions, 1990-2000

17. ME GHG Emissions, 1990

18. ME GHG Emissions, 2000

19. ME GHG Emissions, revised 2000

20. ME GHG Emissions, revised 2000