INFORMATIVO ABCM Nº 092/08 –– Bolsa para Trabalho de Doutorado no Programa de Pós-Graduação em Ciências Mecânicas da UnB

Life Cycle Assessment of Flash Pyrolysis Unit: Scale Up of Laboratory Results to characterize Industrial Scale Environmental Performance

Objectives of the project

The main purpose consists of validating the environmental performance of the concept of a fast pyrolysis reactor for:

• producing bio-oils which meet the specifications required for transport and further upgrading for each projected method of utilisation
• high bio-oils yields (>75%) and high thermal efficiency (80%)
• able to accept a wide range of biomass resources from various origins, in particular those that are identified as the most promising at the national scale.

The main scientific stakes are:

• To evaluate the optimisation parameters of the reactor with regards to mass and energy efficiencies and the specifications of bio-oils produced;
• To define these specification limits regarding each end-application: gasifier (to syngas), petroleum refinery unit or boilers;
• To assess life cycle environmental impact of a potential industrial unit using available pilot plant data.

This project will be developed in the Post-graduate Programme of Mechanical Sciences of the Dept. of Mechanical Engineering of the University of Brasilia. The project is scheduled to start on August 2008.

Description:

LCA analysis shows the actual environmental impacts of the regarded systems, however the possible technical effect of by “scaling up” of processes to commercial plant processes is mostly not considered. Only recently there is available a systematic approach to deal with the problems involved in such scale up process, which acts as a basis of an LCA assumption for the scale up. Additionally, potential synergies between processes in the same line are often not considered.

This Ph.D. thesis proposal aims at considering these aspects for a scale up on the life cycle assessment of environmental performance of a flash pyrolysis semi-pilot unit to reflect real industrial scale performance.

As far as environmental performance is take into account, Life Cycle Assessment (LCA) analysis is carried out for processes and product systems at different development stages: for already commercially existing systems as well as for processes or products at the early design stage. The processes, which LCA experts deal with at development stage, can be one part of the so called “mini plants” or “pilot plants”, sometimes also processes in “laboratory scale”. Using these results as estimation for a results of big scale production processes, would might lead to wrong results. The main reasons for that are, firstly, linked with the fact that taking the processes under development into consideration, although the quality of LCA analysis might be assured due to accurate data collection directly from the processes under scope, the LCA result of these processes do not necessarily present the environmental burdens which would be caused after scaling up to commercial scale (“production scale”). The effects on environmental burdens due to technical scale up are commonly not or at least not entirely considered. Secondly, “synergy effects” between different processes in the same plant are often slighted. These effects occur mostly at pilot plant stages and production plant stages. In LCA often processes are seen as isolated or independent of each other. An example is the use of waste heat from one process to another processes within the same production plant. A further aspect, which is often not considered in LCA studies, is the effect of optimized use of production capacity of single processes in the same production chain.

Depending on the goal and the scope, some LCA studies achieve their goal without considering the effected mentioned above. But in some cases (e.g. comparing LCA studies) the consideration of these aspects is relevant. In spite of that, often scale up effects (including process synergy and production capacity) in LCA studies are neglected. To these days, no systematic procedure has been established, which serve as a guideline to make a systematic “scale up” assumption of LCA possible – therefore, by making assumption, only some single technical scale up aspects are considered, but some are not. In former cases experts are constrained to consider arbitrarily chosen singular scale up effects and to adapt these in the LCA analysis. Thus, the considered aspects are not consistently among these studies.

On this pursuit, this Ph.D. thesis proposal will develop systematic procedure must be used in order to give the LCA experts a guide how to deal with processes under development. This procedure will be applied to assess life cycle environmental performance of a flash pyrolysis unit, already in functioning at the Cirad laboratory of Montpelier.

Biomass is a resource with variable composition, wide geographical dispersion and low energy density. These are important drawbacks when large-scale bio-energy production units are considered: for instance, throughputs of about X million t/year of dry biomass are necessary to make a FT unit competitive. In order to minimise the impact of transport, an alternative to the direct upgrading of biomass consists of preconditioning it on decentralised sites before transportation to a centralised bio-energy production unit.

The route considered in this project is fast pyrolysis for the preparation of a liquid biofuel (in this case bio-oil), which has a promising potential either for overcoming the problem of biomass variability and/or for improving bioenergy system efficiency in both mass and energy terms.

Work programme

The project is divided into 5 main work packages:

• Design and construction of a laboratory scale pilot reactor (3-5 kg/h) at LPF (Experiments will be carried out on different kinds of biomass);
• Evaluating the optimization parameters with regards to mass and energy efficiencies and the specifications of the bio-oils produced;
• LCA : a techno-economic and environmental assessment of the whole pre-conditioning route will be performed from the data collected, and compared to other routes such as torrefaction, etc….
• Modeling of the reactor for its further optimization and scale-up

Project information

_Partners_
Research centres: CIRAD (coordinator);
LPF-SFB
UnB

_Funding _
CIRAD

Submission Period at the Post-Graduate Programme of Mechanical Sciences at University of Brasilia
Deadline – 18th August
Further details can be obtained at http://www.unb.br/ft/enm/pcmec/inscricoes.php .

Contacts for project details:
Professor Armando Pires (armandcp@unb.br)/ Professor Carlos Gurgel Laboratório de Energia e Ambiente, Depto. de Engenharia Mecânica
Universidade de Brasília
Campus Universitário Darcy Ribeiro 70910-900 Brasília DF BRASIL
Tel 55 61 33072054 x234

Dr Patrick ROUSSET (Biomass Energy Research Unit, CIRAD)
Servico Florestal Brasileiro/Laboratório de Produtos Florestais – LPF
L4 Norte,Scen-Trecho 02, Lote 4, Bloco B
BRASILIA DF
CEP: 708 18-900 BRESIL
Tel : (61) 3316 1544
Fax : (61) 3316 1515