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Report

Teaser, summary, work performed and final results

Periodic Reporting for period 1 - Residue2Heat (Renewable residential heating with fast pyrolysis bio-oil)

Teaser

Summary

Residential heating systems have the potential to significantly contribute to the challenges Europe faces to make its energy system clean, secure and efficient. For residential heating systems it is vitally important to use a standardized fuel and create an economically viable value chain.

The long-term objective of Residue2Heat is to enable the utilization of various biomass residue streams in residential heating applications in a sustainable manner. The intention is to replace large amounts of fossil and 1st generation biofuels, currently used in residential heating systems, with biomass residue streams unsuitable for food or feed production, and have a low impact on indirect land use change. This will ultimately increase the share of renewables in the EU primary energy consumption. Unfortunately, most renewable biomass resources are solid materials with low energy density and even the most advanced residential heating systems have difficulties to handle the inconsistent properties of agricultural and forestry residue streams.
Therefore, the specific objective of Residue2Heat is to enable the utilization of sustainable ash rich biomass and residues in residential heating applications to provide sustainable heat at a competitive price. This is achieved by converting various 2nd generation residue streams into a liquid energy carrier at an economic viable scale using the fast pyrolysis process. Subsequently, the fast pyrolysis bio-oil (FPBO) is distributed to residential end-users. The produced FPBO should fulfil applicable specifications for replacement of domestic heating oil and comply with regulations. The ash is recovered from the fast pyrolysis process as a separate stream, and recycling and/or re-use will be assessed. Existing highly efficient condensing boilers are used as starting point in the project, as well as a proven, low emission type of burner. Within Residue2Heat such systems are modified to enable FPBO as fuel. The emission control and energy efficiency of the heating systems are optimized by dedicated modelling of FPBO atomization and combustion kinetics, supported by single droplet combustion tests and spray characterization.

The envisaged concept benefits from the flexible nature of the fast pyrolysis process, allowing the use of various lignocellulosic biomass streams, but also by using modified residential heating systems for which manufacturing capabilities, market development and product distribution are already in place. Dedicated tasks are included to assess the environmental and social impacts, risks analysis and public acceptance. Additionally, business and market assessment activities are performed including specific issues on health and safety relevant to FPBO-fuelled residential boilers.

Work performed

For a number of supply chains, a sustainability analysis has been carried out to identify sustainability and environmental risks. The analysis is carried out for three residual feedstocks: forest residues, bark and straw. In addition, miscanthus is included to represent a cultivated energy crop. The results show that the studied FPBO chains pass the GHG emission saving limits of 60% and 70% of the current Renewable Energy Directive (RED) and its follow up the recently drafted RED2. The emission saving results vary between 77% and 95%, depending on the feedstock utilised. Additionally, it is estimated that more than 90% of the original biomass ash can be recovered. The recycling of ashes as potential soil amendment has been tested with ash from the pyrolysis of clean wood. Up to now the effects of the ashes from the reference biomass (clean pine wood chips) indicate that they can be potentially used for agricultural purposes.

Various biomass resources have been used to produce FPBO at different production facilities. All FPBOs were homogenous good-quality liquids after evaporation of a part of the water. For FPBOs from high-ash content feedstocks it turned out that evaporation, or limited condensation, of a part of the water was an efficient procedure for quality improvement. In the meantime, several methods have been developed to condition FPBO. Promising results are obtained both in decreasing the acidity of FPBO and the extractives content in the FPBO.

Due to the physical and chemical properties of FPBO deposit formation in the fuel carrying components is probably unavoidable when using standard residential heating system components. This was confirmed by the observation of wear and corrosion during the initial testing. The present investigations show that special measures have to be taken for the use of FPBO in residential heating systems. This was expectable and requires further analysis in close interaction with component manufactures in order to produce an FPBO compatible combustion boiler.

By applying detailed measurements of the FPBO properties the consortium partners are able to perform a thermo-physical characterization of FPBO. The data of the FPBO properties are used to obtain the first definition of an FPBO surrogate mixture, consisting of a few reference components. Initial Computational Fluid Dynamics (CFD) modelling has started, although detailed models for FPBO combustion will become available at project end. The present CFD results give additional insights in spray and combustion behaviour and steer the optimisation process of the combustion concepts. In this reporting period, the primary goal was to achieve stable combustion of 100% FPBO at lab-scale conditions. This has been accomplished for several concepts; although based on recent spray nozzle analyses some improvements with respect to emission levels can be achieved.

A preliminary market and business assessment has been performed which focusses on a number of items that are of importance for acceptance of FPBO fuel in the market. Topics covered are economics, alternatives and competiveness. Another important aspect which is taken into account is the specific legislation on EU, national and regional level which can hamper market introduction.

Final results

For residential use, 122 million heat generator systems are installed in Europe at present, about 90% of these heat generators are non-condensing boilers. Natural gas is nowadays the main source of energy (80%), followed by heating oil. The projectâ€™s main target is to use state of the art condensing boiler systems operated with FPBO. This is the logical choice as FPBO contains a significant amount of water and therefore, recovery of the condensation heat is essential to have an energy efficient system.

Introduction of residential boilers that are fuelled with FPBO from biomass residues can contribute significantly to sustainability. Replacing residential boilers that are using fossil fuels like heating oil leads to both savings of fossil fuels and reduction of CO2 emissions. An example is Germany with more than half a million â€“ old fashioned â€“ non condensing oil. Replacement of only 10% of these with FPBO fuelled boilers would reduce the CO2 emissions with about 5.5 million tons per year.

The expected impact from the Residue2Heat project includes the integration of new knowledge on the combustion of FPBO in residential scale heaters between research institutes and manufacturing industry. With this new knowledge, innovative sustainable and cost-efficient heating systems will be developed, which will meet the needs of European and global market.