Particulate Emissions from Domestic Solid Fuel Combustion

Amanda Lea-Langton1, Paul I, Williams2,3, Craig Nutter4, Martin Ashby4 and Gordon McFiggans2

1Tyndall Centre for Climate Change Research, School of Mechanical, Aerospace and Civil Engineering, University of Manchester, Manchester, UK

2Centre for Atmospheric Science, School of Earth and Environmental Sciences, University of Manchester, Manchester, UK

3National Centre for Atmospheric Science (NCAS), University of Manchester, Manchester, UK

4 ESSE Engineering Ltd, Barnoldswick BB18 6BJ

Introduction

• Fine PM : dominant role in the impact of air pollution on human health and on climate through direct radiative effects and cloud adjustments.

• Wood burning has been identified as an important contributor to the UK PM burden.

• Legislation is limited to predefined test conditions rather than to the full range of representative operating conditions of wood stoves.

• Study explores variability of PM properties and composition across a range of conditions using a modern commercial wood burning stove.

UK Woodstove use

0

20

40

60

80

1990 1995 2000 2005 2010 2015 2020 2025 2030

Wo

od

Co

ns

um

pti

on

(P

J)

Heating stoves

Fireplaces

Single house boilers (<50kW)Commercial Boilers (<50MW)

Models have predicted UK residential wood combustion to increase with heating stoves becoming increasingly significant

Solid fuels used for supplementary heating – mainly evenings & weekends200K stoves sold in 2014, up 21% from 2005

Figures from Mitchell et al. Atmospheric Environment 2017. Data from DECC 2015 Sub-national Residual Fuel Consumption in the United Kingdom, 2005-2013

Health impacts

• Ambient PM2·5 was the fifth-ranking global mortality risk factor in 2015, with exposure to it causing 4.2 million deaths and 103.1 million disability-adjusted life-years (DALYs).

• Corresponds to an estimated 29000 premature deaths in the UK per year.

‘There is no evidence of a safe level of exposure or a threshold below which no adverse health effects occur.‘ WHO 2013

http://www.euro.who.int/__data/assets/pdf_file/0006/189051/Health-effects-of-particulate-matter-final-Eng.pdf

Environment InternationalVolume 74, January 2015, Pages 136-14, Journal of Aerosol ScienceVolume 37, Issue 9, September 2006, Pages 1152-116

Black Carbon climate impact

Small scale combustion is often inefficient and hence polluting.

Fine PM is responsible for the aerosol effects that make the single greatest contributory uncertainty to radiative forcing (IPCC, 2013).

J. Geophys. Res.: Atmos. 2013. 118, 5380–5552

Stove testing method variation

For example:• Variation in collection : ESP, heated filter or via dilution tunnel • Some measure isokinetically, some don’t • Up to 40°C sampling temperature difference between methods. • Specification of wood sample (e.g.moisture, bark). • Reporting units : could be as g hour-1, mg MJ-1 , 1.5 g kg-1

Emissions testing is generally carried out under steady state conditions, excluding emissions during the start up and shut down phases which have been shown be substantial

Wide variety of stove test methods to measure total PM around the world and

wide variation between the techniques in each standard

Ecodesign 2022Ecodesign is a European regulation due to be implemented on 1st January 2022 for wood burning and multi fuel stoves.

http://www.stoveindustryalliance.com

• Efficiency improvements

• Reduction in Particulate Matter (PM10 & PM2.5), NOx, CO and OGC (Other gaseous carbon)

It will be illegal to manufacture and sell new stoves from 1st January 2022 that do not comply with the Ecodesign requirements

Experimental methods: Rig 1

Based At Esse Manufacturing Ltd.

• Measurements were taken directly from the flue.

• Burning rate: using High Resolution Platform Scales and VT200 Indicator.

• On line analysis of CO, CO2, O2, NO and NO2 was conducted using a RASI 800 Portable Emissions and Exhaust Gas Analyser.

• Sunset Semi-continuous EC/OC analyser

• Cambustion DMS 500 (Differential Mobility Spectrometer) fast analyser

Stove testing on ‘Bakeheart’ 5kW stove

Experimental methods: Rig 2

• At University of Manchester

Measurements via dilution tunnel or directly from the flue.

• Gas analysis of was conducted using a GASMET FTIR analyser and Testo 350 Portable Emissions Analyser (VOC, CO, CO2, O2, NO and NO2)

• Custom made Particulate Mass analyser (to DINplus specification)

• Dekati impactor for PM10, PM2.5, PM1

• Sunset Semi-continuous EC/OC analyser

• Cambustion DMS 500 fast particulate analyser

1. Real world operation (e.g. air settings, overnight cycle and ‘over-loading’)

2. Novel control devices: filters and catalysts

3. Combustion phase – ignition, flaming, smouldering

4. Fuel: wood type, moisture level and quality

5. Comparison PM Measurement methods

6. Appliance type/technology- variation between Ecodesign compliant models

Work in progress!

Parameters considered

Stages of combustion

Adapted from Brown RCE, Wiley 2011

Particulates from ‘flaming’ different from ‘smouldering‘

Example results- burning rate

Kiln dried wood burns rapidly & is associated with higher PM than ‘seasoned wood’

Good repeatability

Initial results indicate air setting has less effect on burning rate using this stove, however differences in emissions were observed

Example results: Transition from flaming to smouldering phase

DMS data over 1 hour test cycle

Clear distinction observed-shift to smaller particle diameter

Cold start ignition

Flaming phase

Smouldering phase

Particle Size Range – flaming low air

standard air Full air

1.4 E+51.1 E+6

5.0 E+5

Air setting significantly effects flaming phase particulates

Particle Size Range - smoulderinglow air

standard air Full air

2.7 E+5

2.8 E+5 2.8 E+5

Air setting has little effect on smouldering phase particulates

Overnight Particulate Emissions

DMS

EC/OC

Significant increase on the particle mass and size during overnight loading

EC does not peak at the start of the loading/burning

Spots are the mid point of the OCEC scan, bars are the scan time.

Increase at the end is the stove being reloaded

DMS

Conclusions

• Real world operation of wood stoves differs significantly from certification test conditions, so that the actual emissions levels can be higher than forecasted values.

• The results from this work indicate that it is necessary to consider the interdependence of factors such as fuel quality and user behaviour in order to predict more accurately the contribution to Urban PM2.5 levels.

We wish to thank EPSRC for Impact Acceleration Account and Early Career Capital funds to support this work

We also thank the following for their support and useful discussions:• James Allen (University of Manchester)• Suzie Willows (Defra)• Certainly Wood Ltd • HETAS• Stove Industry Alliance

Thank you for listening

Sunset Organic Carbon-Elemental Carbon Analyzer

• Collects aerosol on a quartz-fiber filter, and through the usage of elevating temperature, can differentiate the mass of the collected to either organic or elemental carbon

• First exposes collected aerosol to an increasing temperature ramp in a completely oxygen-free helium atmosphere, where only organic carbon can be converted to CO2

• Laser is inside, any decrease of the laser detection will indicate pyrolysis of the organic material, which is corrected for in analysis software

• The filter is then exposed to a helium-oxygen mix, the presence of oxygen allows elemental carbon to be converted to CO2

References:http://www.sunlab.com/sample-analysis/http://www.sunlab.com/wp-content/uploads/Sunset-Lab-Analysis-Method.pdf

Data Presentation -Thermograms