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Renewable residential heating with fast pyrolysis bio-oil

Periodic Reporting for period 3 - Residue2Heat (Renewable residential heating with fast pyrolysis bio-oil)

Reporting period: 2018-07-01 to 2019-12-31

Alternative sustainable fuels for residential heating are needed in the household sector to reduce greenhouse gas emissions. Currently, even the most advanced residential heating systems are unable to handle the difficult, inconsistent properties of agricultural and forestry residue streams. There is a particular need to improve efficiency of low emission biomass heating systems while widening the feedstock base.
The overall objective of the project, Residue2Heat is to enable the utilization of various biomass residue streams in residential heating applications in a sustainable manner. For this, a two-step approach is followed in which biomass residue streams are first converted into a uniform, second generation liquid biofuel via fast pyrolysis called fast pyrolysis bio oil (FPBO). Secondly, existing residential heating systems are tailored and optimized to allow the use of FBPO. (See Figure Overall Objective).
The main outcome of the EU H2020 project Residue2Heat is the development of stand-alone, small scale residential boilers (20-60 kWth) fuelled with fast pyrolysis bio-oil (FPBO). Further achievements include the production of high quality FPBO from high ash biomass residues, atomization and combustion of FPBO, design and manufacturing of modified burner components and a logistics plan for storage and handling. The novel FPBO fuelled boiler is meeting most operational and environmental demands in the actual intended environment (TRL5).
Various biomass streams, bark, Miscanthus, sawdust, (forest) thinnings, wheat straw and clean wood, have been used to produce FPBO at different production facilities; pilot scale and mini scale. For FPBOs from high ash content feedstocks the evaporation of a part of the water was an efficient procedure for quality improvement. By blending and esterification the acid content could be decreased to achieve a low-acid FPBO. A pathway has been proposed to define a standard FPBO, by combining the information gathered in this project of FPBO properties, spray and combustion behaviour, safety issues, logistics, storage and future exploitation. It is concluded that the flashpoint of FPBO would be an important factor for which limited data is available. Due to the physical and chemical properties of FPBO, deposit formation, wear and corrosion can occur in the fuel carrying components when using conventional residential heating system components. Therefore, special measures have to be taken for the use of FPBO in residential heating systems.

By applying detailed measurements of the FPBO properties the consortium partners are able to perform a thermo-physical characterization of FPBO leading to a detailed kinetic combustion mechanism for FPBO and a 3D model for single droplet evaporation which was validated with experiments. These have been in turn used to model the developed FPBO burner with Computational Fluid Dynamics (CFD). The CFD results give additional insights in spray and combustion behavior and steer the optimisation process of the burner concepts. On the experimental front, based on an existing combustor unit (20 kW), several iterations and adaptations for FPBO combustion have been performed. With the latest redesign of the burner, the combustion of 100 % FPBO showed very good results with respect to combustion stability and emission levels of CO. The NOx emissions, which stem from the fuel nitrogen, are high compared to domestic heating oil but comparable to pellet stoves. Furthermore, long term combustion test of the modified burner was performed where the demonstrator lab scale burner 20 kW was up and running for 100 hours.

Environmental impact assessment (4 feedstocks) confirms positive impacts of FPBO heating compared to fossil alternatives, especially GHG emission reduction (82 - 92 %). Furthermore, FPBO fly ashes have a potential use for providing nutrients for soil ecosystems. The economic evaluation shows that the concept is cost-competitive with current fossil standards without the need of incentives, generating high innovation potential. In the last few months of the project, the future of liquid fuels has been reoriented due to extensive political decisions. This may be an opportunity for biofuels from residues but also a strong decrease in sales of oil burners is expected. Current legislation for 5 key countries has been updated on EU, national and regional level. Items covered are a.o. the status of FPBO as fuel/biomass, emission and permitting. Recommendations for the storage and handling of FPBO at residential level have been provided. The risk and mitigation plan has been followed up and actions taken when required. Lastly, a step-by-step roll-out plan for the use of FBPO in residential heating has been developed.

Various types of data generated in R2H have become available to stakeholders in the form of project reports and open access publications e.g. articles as eye-catchers on cover pages of high-impact journals. In December 2019, a public workshop was organised in Aachen, Germany to disseminate the main achievements of the project among the residential heating industry as well as its associations and to foster the exchange of the newest scientific and technical results between industry, researchers, and experts. Moreover, a poster session with ca. 15 posters provided a comprehensive summary of results from each project partner. Furthermore, the developed concepts will pave the way for future exploitation. 2 concrete examples include
- use of FPBO in other applications, e.g. Combined Heat and Power generation in EU Horizon 2020 Project SmartCHP. The knowledge that has been generated in this project with respect to the combustion and processing of FBPO will give a headstart to the SmartCHP project.
- The novel FPBO fuelled burner meeting all operational and most environmental demands is being operated and monitored in actual intended environment (TRL5). It is meant to further develop the system as well as a showcase for potential customers. Monitoring will be continued after the R2H project.
The highlights from the impact expected (see attachment) are:
Socio-economics: Residential boilers that are fuelled with FPBO from biomass offer increased economic activity and jobs within the region due to local production of FPBO without fossil fuel export. A roll out plan for the technology introduction in the market has been developed after interviews with gas, oil and pellet heating system owners to ensure a positive public acceptance.
Environment: The sustainability chain evaluation of various FPBO types (based on feedstock) showed emission savings of 80-94%, meeting GHG emission saving requirements of 60% and 70% of the current RED and RED2, respectively. Furthermore, the ashes derived from the FPBO production process have potential for providing nutrients for soil ecosystems and could therefore be used for agricultural applications.
Market Transformation and Policy: Relevant data to support FPBO-REACH registration and standardisation (CENTC19/WG41) for residential heating has been collected. This data has been documented in a concept technical report for standardisation for the use of FPBO in residential boilers. Access to policy making channels is based on multipliers by using the participants relevant memberships and committees and sustaining members of the participants which communicate the dissemination and exploitation potential of the project outcomes.