European Low-emissions High-efficiency

Biomass-fired Technologies 

NESCAUM Directors Meeting

Boston, MA

June 26, 2008

Raymond J. Albrecht, P.E.

New York State

Energy Research and Development 

Authority

Albany, New York 

Lisa Rector

Senior Policy Analyst

NESCAUM

Boston, MA
Biomass Combustion

Take Home Message

Low emissions Possibly

Energy efficiency Possibly

Economic benefits Yes
The Concern

Swiss Research - Chemical Composition of PM from Wood Combustion

Poor combustion - PM carbon-based

Clean combustion - PM inorganic salt-based

Comparison of PM filters from diesel 

and clean wood combustion
Swiss Study of Relative Toxicity of Wood Smoke vs. Diesel Soot

Are European Boilers Cleaner???
Comparative Emissions

Commercial boilers Energy Efficiency 

(%)

Fine particle emissions

(lb/MMBtu)

US Conventional wood chip 70-75 0.2

European high efficiency and low 

emission chip or pellet 

(residential and commercial)

85-90 0.01-0.07

European high efficiency and low 

emission chip or pellet w/ ESP or 

baghouse

85-90 0.002-.02

No. 2 oil (2500 ppm S) 80-85 0.005

No. 2 oil (500 ppm S) 80-85 0.001

NO. 2 oil (15 ppm S) 85-93 0.00002-0.00004

Natural Gas 80-90 0.00002
Improved Energy and Environmental Performance

Of Wood and Biomass-fired Heating Systems

Decreasing emissions

Increasing efficiency
Total Annual Emissions from Small Wood and Biomass Combustion

in Lower Austria

Note: Average PM values have continued to decrease with time 
Potential Markets for Wood and Biomass-fired Systems

Schools Businesses District Heating
Firewood and wood

pellets account for 25 

percent of heating 

energy in Austria

BLT is the leading

independent 

certification lab in 

Europe for biomassfired heating systems

Austrian Bio-Energy

Centre works with 

industry on R&D 

challenges
Low Emissions Wood Combustion Technology

Gasification and Staged Combustion - separate 

paths for primary and secondary combustion air. 

About 40 or 50 percent primary air.

Maintain about 1200 deg F in gasification 

chamber. Lower temperature gasification helps 

to reduce soot formation by reducing fuel rich, 

high temperature zones in flame. Also reduces 

ash-based particle formation.
Technology Requirements for 

Low Emissions Wood Combustion

•Pre-heated combustion air 

•Insulated secondary combustion chamber

•Residence time in secondary combustion chamber

•Oxygen sensor to automatically control Air/Fuel Ratio

•Forced combustion air supply to control firing rate

•Computer aided analysis to optimize firebox design
European Woodstove Manufacturers

• RIKA

• The Eco-plus

– Modulated air flow

– CFD air flow models
Specht – Twinfire
Swiss Woodstove Emissions Research

Field Emissions Type 1

Pre –

NSPS

g/hr

Type 2

ceramic.

g/hr

Type 3

Staged 

Comb.

g/hr

Filterable PM 24.8 0.7 0.3

TOC 37.0 2.7 <0.02

Secondary 

filter

8.6 0.6 <.005

Total 

condensables

45.6 3.3 <0.03

Total PM 69.9 4.0 0.40

0.40 g/hr = 0.13 lb/mmBtu
Residential furnaces

• KWB

– wood boiler systems from 

10 – 300kW

– Standard features include 

automatic ignition, 

automatic boiler cleaning 

and automatic ash and soot 

extraction 

• Other industry leaders 

include Kohlbach and 

Urbas
European Wood American Oil-fired

NOx 0.08 0.10 lb/MMBtu

CO 10 to 60 10 - 30 ppm

PM 0.01 - 0.07 0.005 lb/MMBtu

Typical Emissions from European

Wood-fired Boilers up to 1 or 2 MMBtu/hr
Commercial Units

• Stricter emission standards in Europe

– In Switzerland, new units over 1.8mmBtu 

required to have ESP now . By 2012 existing 

units must have ESP or equivalent controls 

– Before controls (ESP or baghouse), total PM 

emissions range from 0.01 to 0.07 lb/mmBtu

– Most units are equipped with multi-cyclone and 

baghouse or ESP

• European systems capable of meeting standards, 

US units would not
Comparison of European and US 

Wood Emission Standards

lb/mmBtu

0.054 0.054

0.01

0.6

0.3

0.25

0.2

0.1

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

Current

Swiss

Current

Germany

Germany

2015

NY limit NH limit VT limit RI limit MA
• Industry leaders in 

Europe include:

– Schmid 

http://www.holzfeuerung.ch

– Kohlbach 

http://www.kohlbach.at

– Bertsch 

http://www.bertsch.at

– Standard
Post - Combustion Treatment

In Europe use of 

advanced controls is 

commonplace!!

•Cyclones – used as first stage of 

control to eliminate coarse particles 

but not viewed as adequate control

•Baghouses – used but expensive 

and require maintenance

•ESPs – commonly used and 

effective with fine particles but are 

vulnerable to fouling under heavy 

load conditions
Electrostatic Particle Filter for Clean Wood

Combustion Systems

Ruegg-Cheminee AG in Switzerland
So what else is happening in 

Europe???
Pellet Heating Systems

In Austria

New emissions standards implemented in early 1990's 

led to development of ultra-clean pellet combustion 

Bulk delivery and storage of pellets 

Pellet heating system sales have skyrocketed

In Austria and several other European countries

Sales of pellet-fired systems now equal or exceed

oil-fired heating systems in several regions of Europe

Fuel standards for pellets – size, makeup, binders, etc
Micro CHP
Integration with Solar Thermal Energy
Agricultural-based Fuels
Crop-based Pellet Fuels

Ash and Sulfur Content

Crop-based solid biofuels show interesting 

potential but high (3 - 5 %) ash contents can 

cause operating challenges

Some crop-based pellets have 0.1 % sulfur 

content (equivalent to high sulfur heating oil)

SO2 emissions not thoroughly tested yet
Oeko Therm - manufacturer of biomass 

boilers for fuels with high ash content

Located in southern 

Germany
Sales of Wood and Biomass Boilers
Questions???