Climate Change Effects of Biomass and Bioenergy Systems

Zagreb, Croatia 2000

Bioenergy, Greenhouse Gases And Carbon Sequestration

Task 25: Greenhouse Gas Balances of Bioenergy Systems

22 – 26 May 2000 – Zagreb, Croatia

Jointly organized by

Energy Institute
“Hrvoje Pozar” Ltd.

HR-10000 Zagreb
EKONERG holding
Ulica grada Vukovara 37
HR-10000 Zagreb, CROATIA
Elisabethstrasse 5
A-8010 Graz, AUSTRIA




IEA Bioenergy is an international, collaborative research programme on Bioenergy. The primary goal of IEA Bioenergy Task 25 (“Greenhouse Gas Balances of Bioenergy Systems”) is to investigate all processes involved  in the use of bioenergy systems, on a full fuel-cycle basis, with the aim of assessing overall greenhouse gas balances. Participating countries are Australia, Austria, Canada, Croatia, Finland, New Zealand, Sweden, United Kingdom, and the  USA.

The Task 25 workshop in Zagreb, Croatia, is part of a series of workshops within Task 25 taking place on a regular basis.

Scope Of The Workshop, Events

Demonstration of and hands-on experience with computer tools for greenhouse  gas balances of bioenergy and carbon sequestration systems

Carbon/greenhouse gas models for bioenergy, forestry, wood products, land-use and land-use change have been, or are being, developed by participating countries. 4 models were presented in detail, with time allowed for participants to use the models. The following models were presented at the workshop.


CO2FIX is a tool which quantifies the C stocks and fluxes in the forest (whole tree), soil organic matter compartment  and the resulting wood products. It was originally designed for even aged monospecies stands in the Netherlands (Mohren and Klein Goldewijk 1990a), but has also been used for a wide variety of (mostly even aged) forest types from all over the world, including some selective logging systems (Nabuurs and Mohren 1993). The latter results have been used in the  IPCC 1995 climate change assessment (Brown et al. 1996).

Compared to the previous version of CO2FIX which was documented in Mohren and Klein Goldewijk (1990b), the present version

  • is a user friendly windows-based version.
  • is more precise in the allocation of harvested wood from thinnings and final fellings to wood product groups;
  • has an option to choose for recycling;
  • can directly sum the output of one forest type to larger areas;
  • directly presents some of the output in a graph.

The current version is under further development in an EU funded project, “Carbon sequestration in afforestation and sustainable forest management: presentation of a general evaluation tool and generic case studies, CASFOR”.


GORCAM is an Excel spreadsheet model that has been developed to calculate the net fluxes of carbon to and from the atmosphere associated with land use, land-use change, bioenergy and forestry projects. The model considers:

  • changes of carbon (C) stored in vegetation, plant litter and soil,
  • reduction of C emissions because biofuels replace fossil fuels,
  • C storage in wood products,
  • reduction of C emissions because wood products replace energy-intensive materials like steel or concrete,
  • recycling or burning of waste-wood,
  • auxiliary fossil fuels used for production of biofuels and wood products.

The model makes use of approximately 200 input parameters. For each scenario a new set of input parameters can be  defined. They describe the management regime (harvest cycle, growth rate etc.), the land use before the project, and the way in which the biomass is used for carbon mitigation. Various biomass growth functions are availabe (including Richards function, possibility of precommercial thinning, and selective logging). The soil and litter  carbon uptake or release can either be prescribed with exogenous assumptions or a dynamic calculation scheme can be used.

The model can be used to assess the future carbon balance for scenarios involving:

  • a forest stand,
  • a forest plantation system (normal forests), and
  • a forest with a given age-class distribution (to deal with natural disturbances).

The model output is presented in diagrams with cumulative carbon sequestration in various carbon pools over time. The model also allows to view the individual carbon fluxes. In addition to the regular model  output, another mode is available where future carbon fluxes are discounted to give a net present value.  The higher the discount rate and the longer the time horizon, the more the results will differ from the basic output.

GORCAM is implemented in MS Excel 5.0, and makes use of Visual Basic Macro Programming. Each scenario can be saved as an Excel file, that still carries with it all the model features, including macros, diagrams and equations. GORCAM allows the performance of sensitivity analyses, whereby the impact on any model output of varying an input parameter can be assessed. In combination with Excel-compatible risk analysis tools such as Crystal Ball or @Risk, Monte Carlo Analyses can be carried out to determine the uncertainty of the model results. Probability distributions  can be defined or chosen for all input parameters, and the model derives the probability distribution for any model output, for example, the carbon sequestration of a given project after 20 years.


The model ERGO has been developed for estimating energy and emissions budgets of bioenergy systems. ERGO was originally developed in the early 1990’s with the primary aim of estimating energy and carbon budgets of bioenergy  production from short rotation coppice tree systems. An important secondary objective was to provide a tool that could be used to compare different systems of bioenergy production directly, consistently and fairly. To achieve  this ERGO needed to meet three important criteria, specifically the methods of energy and carbon budget estimation needed to be:

  1. general: the model can be applied without restriction to the study of widely differing types of bioenergy  production system, both annual and perennial, as well as woody and non-woody.
  2. consistent: although the model is designed to be flexible, offering alternative methods of data input  and calculation, at the same time the model imposes an essential discipline and structure on budget  estimation, and ensures the use of common data sets where appropriate.
  3. transparent: assumptions and calculations are described in detail in the input and output files  of the model. Gaps in understanding or limitations in data can be readily identified.

ERGO’s role in providing fundamental calculations of energy and emissions budgets of bioenergy systems may be viewed as underpinning GORCAM’s policy-level projections of carbon sequestration potential and greenhouse gas balance impacts. Currently the estimation of greenhouse gas balances in ERGO is limited to the carbon balance,  but extension of the model to represent other gases is straightforward.


GEMIS (Global Emission Model for Integrated Systems) is a computerized life-cycle analysis model, LCA database,  and cost-emission analysis system. It offers environmental and cost data for energy, material, and transport systems,  including their life-cycles. The environmental data cover air emissions, greenhouse gases, liquid effluents, solid  wastes, and land-use. The cost data concern investment, fixed annual, and variable cost, as well as externality  factors for air emissions, and GHG. Further data are stored for “meta” information: comments and description,  references, data quality indicators, location and statistical group.

GEMIS determines full life-cycle impacts of energy, transport, and material technologies. In addition to the totals, GEMIS also gives the individual contributions of all processes to a calculated result (breakdown ), and can determine results for selected system boundaries (e.g. a special location, in- or exclusion of material acquisition, crediting).

GEMIS evaluates deviations from multiple objectives (trade-offs), e.g., costs vs. emissions, or emissions vs. land use. It further calculates CO2 and SO2 equivalents, and the total resource use (cumulative energy and material  demands). Because of the modular approach of the database (“unit” processes), the sensitivity of any  result can be determined quickly by copying original data, and adjusting key parameters – within seconds, GEMIS then calculates the new results which can be compared immediately with the original data.

The software is public domain (i.e., free of charge), and updated regularly. More information can be found on the  GEMIS websites [ (in  German), and].


A full-day study tour was undertaken to visit wood industry ITC in Varadin. The company has an advanced  system of wood waste use, which includes a modern heating plant and mill for briquettes. The company is also known because of children toys and furniture production. Two other interesting visits were made – Veliki Tabor and Trakoscan castles, which are close to the study  tour route.


Workshop Program

MONDAY, 22 MAY 2000

Session 1: Presentation and demonstration of CO2FIX

CO2 fix
Ari Pussinen
European Forest Institute, Joensuu, Finland


Carbon Assessment Model for Forests (CAMFor)
Chris Brack
Australian National University, Canberra, Australia

TUESDAY, 23 MAY 2000

Session 1: Continued

Carbon Assessment Model for Forests (CAMFor) continued
Chris Brack

Ari Pussinen
European Forest Institute, Joensuu, Finland

Session 2: Presentation and demonstration of GORCAM

GORCAM (Graz Oak Ridge Carbon Accounting Model)
Bernhard Schlamadinger
Joanneum Research, Graz, Austria

Modelling the effect of thinning and pest control on the carbon balance of a stand
Doug Bradley
Domtar Inc, Ottawa, Canada




Session 3: Presentation and demonstration of ERGO

Robert Matthews
Forest Research (Forestry Commission Research Agency) Farnham, United Kingdom

Session 4: Presentation and demonstration of GEMIS and the database of bioenergy systems in Austria

GEMIS and the database of bioenergy systems in Austria
Gerfried Jungmeier
Joanneum Research, Graz, Austria

FRIDAY, 26 MAY 2000

Session 4: Continued

GEMIS and the database of bioenergy systems in Austria continued
Gerfried Jungmeier

Progress with FLAMES and CASC: a market oriented approach  to carbon cycle management through sequestration and biofuel
Peter Read
Massey University, New Zealand

IEA Bioenergy Task 25 Business Session

IEA Bioenergy Task 25 – Administrative Matters
1. Task participation; Task continuation beyond 2000
2. Task 25 website
3. Subprojects

  • Baselines paper
  • FAQ
  • Overview of National Research Programmes

4. Posters and transparencies
5. IPCC issues
6. Possible proceedings of modelling workshop
7. Woody Biomass as an Energy Source Conference (25 – 28 Sept 2000, Joensuu, Finland)
8. Miscellaneous items

  • Exchange of Scientists
  • Sevilla
  • ExCo Presentation
  • Industrial involvement
  • Other needs of participating countries


List of Participants

Name Institution Address Phone Fax e-mail
BRADLEY, Doug Domtar Inc. 700-1600 Scott Street, Ottawa, Ontario K1Y 4N7, CANADA +1 613 725 5 6859 +1 613 725 6820
BRACK, Cristopher Dept. of Forestry, Australian National University Canberra, ACT 0200, AUSTRALIA +61 26249 3535 +61 26249 0746
CANELLA, Lorenza Joanneum Research Elisabethstrasse 5, 8010-Graz, AUSTRIA +43 316 876 1341 +43 316 876 1320
DOMAC, Julije Energy Institute “Hrovje Pozar” Ulica Grada Vukovara 37, 10000 Zagreb, CROATIA +385 1 6322 848 +385 1 6118 401
FIJAN-PARLOV, Snjezana EKONERG Ulica grada Vukivara 37, HR-1000, Zagreb, CROATIA +385 1 6322 908
GARCIA QUIJANO, Juan F. Laboratory of Forest, Nature and Landscape Vital Decosterstraat 102, 3000 Leuven, BELGIUM +32 1 6329 770 +32 16 329760
JÄKEL, Ulrich Joanneum Research Elisabethstrasse 5, 8010-Graz, AUSTRIA +43 316 876 1423 +43 316 876 1320
JELAVIC, Vladimir EKONERG Ulica grada Vukivara 37, HR-1000, Zagreb, CROATIA +385 1 6115 189 +385 1530 604
JUNGMEIER, Gerfried Joanneum Research Elisabethstrasse 5, 8010-Graz, AUSTRIA +43 316 876 1313 +43 316 876 1320
KARLSSON, Asa Environmental and energy systems studies, Lund University Gerdagatan 13, SE-223 62 Lund, SWEDEN +46 46 222 4833 +46 46 222 8644
MATTHEWS, Robert Forestry Commission Research Agency Alice Holt Lodge, Wrecclesham, Farnham Surrey, GU10 4LH,UNITED KINGDOM +44 1420 526 235 +44 1420 23450
MESIC, Milan University of Zagreb, Faculty of Agriculture Department of General Agronomy, Svetosimunska 25, Zagreb, CROATIA +385 1 23 93 956 +385 1 23 93 814
NIKOLAOU, Natassa Center for Renewable Energy Sources 19 Marathanas Ave, Pikermi, GREECE +30 1603 9900 +30 1603 8006
PINGOUD Kim VTT Energy P.O.Box 1606, Espoo, 02044 VTT, FINLAND +358 9 456 5074 +358 9 456 6538
PUSSINEN, Ari European Forest Institute Torikatu 34, FIN-80100 Joensuu, FINLAND +358 13 252 0241 +358 13 124 393
READ, Peter Massey University Private Bag 11222, Palmerston North, NEW ZEALAND +64 6355 9194 +64 6350 5660
ROBERTSON, Kimberly Joanneum Research and Forest Research (NZ) Elisabethstrasse 5, 8010-Graz, AUSTRIA +43 316 876 1330 +43 316 876 1320
ROBEK, Robert Slovenian Forestry Institute Venca Pot 2 1000 Ljubljana, SLOVENIA +386 1 200 7800 +386 1 257 3589
SCHLAMADINGER, Bernhard JOANNEUM RESEARCH Elisabethstrasse 5, 8010-Graz, AUSTRIA +43 316 876 1340 +43 316 876 1320 bernhard.schlamadinger@
WAUPOTITSCH, Michael JOANNEUM RESEARCH Elisabethstrasse 5, 8010-Graz, AUSTRIA +43 316 876 1337
WEST, Tris Oak Ridge National Laboratory P.O. Box 2008, MS 6335, Oak Ridge, Tennessee 37831-6335 USA +1 865 574 7322 +1 865 574 2232