GHG emissions from landfills for EPER reportingIan Whitwell

Pollution Inventory team

Environment Agency of England & Wales

EPER reporting process PPC regulations from IPPC Legal Notice: report annual mass emissions to

national inventories: England/Wales: Pollution Inventory Scotland: Scottish Pollutant Release Inventory Northern Ireland

EA collects/extracts required data for EPER submission - 2002 emissions data submitted

Landfills, incinerators most relevant operations Relevant GHGs: CH4, CO2, N2O, CFCs etc

Landfills New to Inventory reporting Decision to provide a reporting tool. Ease of

use important Landfill risk assessment tool being developed

for use in permitting landfills: GasSim Use source term as basis for Inventory

reporting: GasSimLite Freely available from www.gassim.co.uk Currently use non-mandatory

GasSim conceptual model

GasSimLite

Principles The scientific principles implemented in

GasSim also underpin the 2002 revisions to the UK National Assessment Model (Bob Gregory will describe more tomorrow)

GasSim is a probabilistic model Parameter uncertainty expressed as pdf Output for Inventory reporting is 50th percentile Validation studies

The Source term Gas generation module primarily considers:

Infiltration Waste mass and breakdown, e.g. % domestic, industrial, etc Waste composition and biodegradability Waste degradation rates Water balance Landfill engineering design

Emissions module considers: Gas engines and flares Methane oxidation in the cap (IPCC or fracture model) Surface emissions Lateral emissions

Landfill engineering Four types of

cap are available

Seven types of basal liner design are available

IPCC default approach for methane oxidation

A mechanistic model of methane oxidation is available

Waste inputs

Gas plant Specify gas

engines and flares

Turndown ratios Gas collection

efficiency Air-fuel ratios Destruction

efficiency

Use in practice

Nearly all UK IPPC landfills now report CH4, CO2 and other GHGs using GasSim(Lite)

In general default values are used Some concerns from operators in defining

historical waste inputs First used for 2002 emissions reporting Experience suggests 2-3 yrs until reliable use

Potential benefits for GHG reporting Site specific data: ‘bottom up’ data should

provide better national estimates Emissions data available for other GHGs if

required: CO2, CFCs etc Approach consistent with IPCC Tier 2

methodology for CH4

CH4 emission estimates for UK landfills

Note:

- PI includes emissions for England & Wales only

- EPER includes England, Wales, Scotland and Northern Ireland

* no QA

Future options More feedback on use of GasSimLite by

landfill operators. Verification process Understand reasons for differences between

‘bottom-up’ (EPER) and ‘top-down’ (IPCC) national estimates

Include uncertainty Consider use of EPER data for national CH4

estimates