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NNE5-2001-00744
Pyrolysis Oil Toxicity Assessment for Safe Handling and Transport - BIOTOX |
| Contract No: | NNE5-2001-00744 |
| Source: | Final Technical Report, June 2005 |
| Source: | Project details, February 2004 |
Download -
Final Report (762 Kb PDF)
The following text is abstracted from this 57 page report.
Pyrolysis is one of the three main thermochemical routes to convert biomass into useful primary energy products. It consists in the heating of a raw material in absence of oxygen. As a result of the thermal decomposition of the raw material, a gas, a liquid and a solid are formed, which can be used directly or further upgraded to give more value-added fuels. Fast pyrolysis at a temperature around 500°C, at very high heating rates and short vapour residence times (less than 1 second) gives high liquid yields of up to 80% weight on a dry feed basis. Fast pyrolysis is therefore unique in that a liquid product is produced in high yields in a simple one step process with all the advantages offered by a liquid fuel.
The White Paper edited by the Commission has described biomass as the most important source of renewable energy for the future. In the long term, biomass will undoubtedly play a significant role in the supply of energy in many countries. The project intends to assess and minimize the effect of a liquid fuel (bio-oils) from fast pyrolysis of biomass, on human health and its impacts on environment, before large scale marketing and utilisation, by acting on the production parameters. It aims at producing cleaner bio-oils to both at local and global scale.
The development of the use of bio-oils as fuels will have a positive impact on the reduction of CO2 emissions as they derive from biomass (CO2 neutral).
More generally speaking, the development of the use of bio-oils will increase the use of European forest and agricultural products and by products. From an economic viewpoint, this will induce job creations in rural areas, thus developing economic and social welfare. The most promising application of bio-oils is electricity production, or combined heat and power, due to their ability to be used in an engine without extensive upgrading as well as the ability to decouple the fuel production source from the end-use location. Small size (a few MWe) decentralised electricity production can be achieved, which will allow the development of activities in less favoured regions.
An other very attractive option offered by fast pyrolysis is transport fuel application through bio oil gasification and Fischer Tropsch reaction as fast pyrolysis offers a unique advantage of decoupling the production phase of its use as well as generating standard fuel form dispersed and divers biomasses. Adapted health and safety procedures are important and will have running cost reduction implication as it will allow appropriate risk evaluation and a better insurance coverage. More over a better understanding of operating conditions responsible for more severe toxicity and eco-toxicity will improve day-to-day operation and reduce losses.
Scientific/technological objectives of the project.
Fast pyrolysis has benefited from active research programme since 1980€s because bio-oils can be substituted directly for fuel oil in many static applications or used as a source of renewable chemicals and in the longer term it can be upgraded for more demanding applications such as transport fuel. Today, different demonstration plants are set up in Europe as well as in North America and significant quantities of bio-oils are produced for research and development purposes. Thus, the question of safety procedures for human health and environment preservation is raised during production, transport and use of the bio-oils. Indeed bio-oils contain 100s of chemicals from different functional groups, such as organic acids, aldehydes and ketones, phenolic compounds, aromatics. Their composition mainly depends on the feedstock used and the pyrolysis conditions. Thus, the toxicology of the oils also depend on feedstock and process. No systematic studies were made to relate the different parameters. This was mainly due to the high cost of the necessary toxicological and biodegradability studies, which prevents their financing by generally SMEs fast pyrolysis companies.
Moreover with the increasing amount of bio-oils manufactured, transported (imported) and stored within the EU market, it was necessary to register (notify) this substance by competent authorities with a comprehensive and definitive MSDS and proper preventative and remedial procedures to adopt during production, transport and use of bio-oils.
Base on these observations during the project, the relation between process parameters on one hand and chemical composition and toxicity for human health and environment on the other hand were investigated. Then, a bio-oil, selected to be representative of those placed in the Eu market, was submitted to mandatory tests required by the commission, the objective being the definition of secure handling and storage procedures, in order to control the risks related to the product for the population and the environment. The effects of different ways of exposure (inhalation, ingestion or skin contact) were quantified, as well as the effects of long term exposures. The impacts on the environment was also be evaluated by biodegradability, and effects on bio-organisms.
The aims of this project were:
Discussion
The screening tests indicate a wide variability in chemical composition measured by GC and little difference in toxicological properties of the bio-oils. It is well known that depending on process conditions the relative proportions of sugars, acids and aldehydes vary in bio-oil. These groups contain the chemicals with the highest mass proportions in bio-oil, notably acetic acid, hydroxyacetaldehyde and anhydrosugars, which are known to have low toxicity. The results of the screening tests indicate that the variations in these groups do not materially impact the overall toxicity of the bio-oil, which they could in theory through synergistic or antagonistic effects.
There is an indication that the concentration of PAH may correlate with toxicity, as the two slow pyrolysis oils had both the highest PAH concentrations and showed the greatest toxicity. PAH are also well known to contribute to health and safety concerns in conventional petroleum derived fuels. The results also provide relevant information for the labelling, storage and transportation of bio-oils. They indicate that the oils do not need special precautions in terms of explosive concerns, or toxic or ecotoxic emissions. They are, however, corrosive and irritating to skin and therefore require appropriate personal protective equipment during handling. The data generated in this work can also be used to help produce an MSDS sheet and technical dossier for bio-oil as required by incoming European legislation on chemicals control, as will be discussed in detail in the final project report.
Conclusions
The results indicate that in spite of substantial variations in the proportions of some chemicals contained in different bio-oils, all fast pyrolysis processes give bio-oil that is very similar in terms of toxicity, eco-toxicity and biodegradability. Bio-oil appears to be more benign than slow pyrolysis derived tars, although it takes longer to biodegrade. In comparison to traditional petroleum derived fuels bio-oil biodegrades faster, and is considerably less toxic.
Introduction
Pyrolysis is one of the three main thermochemical routes to convert biomass into useful primary energy products. Fast pyrolysis has benefited from an active research programme since the 1980's in order to obtain bio-oils, which can be used in engines for the generation of electricity or after refining in transport. Today, several demonstration plants are operating in Europe and North America where significant quantities of bio-oils are produced for research and development purposes and several commercial plants are at an advanced stage of planning. Thus for a commercial development, the question of safety procedures for human health and environment preservation is raised.
In this project, the relationship between process parameters on the one hand and chemical composition and toxicity for human health and environment on the other will be investigated, so as to recommend the operating conditions to produce bio-oils with the lowest impacts. Then the optimised compositions of bio-oils will be submitted to the mandatory tests required by the EU legal authority, the objective being the definition of secure handling and storage procedures, in order to control the risks related to the product for the population and the environment.
The effects of different ways of exposure (inhalation, ingestion or skin contact) will be quantified, as well as the effects of long term exposures. The impacts on the environment will also be evaluated by biodegradability, chemical oxygen demand (COD), biochemical oxygen demand (BOD) and the effects on bio-organisms. A MSDS safety procedure and guidelines for bio-oils use and transport will be published in order to allow oil producers to legally market and transport on the European market.
Activities
The project will proceed in four steps as follows:
Expected results
An appropriate assessment of the risk involved, and the definition of the best practice for the production of the most benign bio-oil in terms of health and the environment, will contribute to reduce the production costs and make pyrolysis bio-oil more competitive. In addition, the knowledge of the parameters potentially responsible for toxicity will limit production losses. The MSDS safety procedure will allow a free exchange of the bio-oil throughout Europe and the world. The results will be widely published on the existing PyNe's website, as well as in the newsletter.
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