Solar-Biomass Reversible energy system for covering a large share of energy needs in buildings

Project Information

SolBio-Rev

Grant agreement ID: 814945

DOI

10.3030/814945

Project closed

EC signature date 21 March 2019

Start date 1 May 2019

End date 30 April 2024

Funded under

• SOCIETAL CHALLENGES - Secure, clean and efficient energy

Total cost

€ 4 790 536,25

EU contribution

€ 4 790 536,25

Coordinated by

ETHNICON METSOVION POLYTECHNION
Greece

Periodic Reporting for period 3 - SolBio-Rev (Solar-Biomass Reversible energy system for covering a large share of energy needs in buildings)

Reporting period: 2022-05-01 to 2024-04-30

Summary of the context and overall objectives of the project

The SolBio-Rev project aims at the development of an innovative renewable energy system for the production of space heating, cooling, domestic hot water and electricity to meet all heating/cooling, and part of electricity demand of a building.
The heart of the system is a novel reversible heat pump configuration coupled with multiple innovative renewable systems; adsorption chiller, evacuated tube solar thermal collectors equipped with thermoelectric generators (TEGs), a low-emissions biomass boiler with capability of high-temperature supply operating at combined heat and power (CHP) mode, and a smart control system.

The original objectives of the project are listed below:
•Development of a cascade chiller with advanced heat exchangers to reach an electric Coefficient of Performance (COP) > 6 for space cooling production in south Europe
•Development of a reversible heat pump/ORC system using an environmentally friendly refrigerant to reach a COP > 4.5-5 for solar-assisted operation and an ORC efficiency of up to 8%
•Development of an innovative evacuated tube solar thermal collector with TEGs to convert the otherwise wasted, lower-temperature heat into electricity
•Development of a biomass boiler for CHP operation with capability of high-temperature heat supply (up to 120 °C) and reduced air pollutants by over 20%
•Development of predictive and smart control
•Interaction with potential stakeholders for considering their needs during the design process and enhancing uptake across EU
•Realisation & testing of two SolBio-Rev prototype systems in small-scale pilot buildings at two diverse climatic zones (Greece, Germany)
•Validation of the SolBio-Rev concept based on the test results of the two pilots, for reaching an energy share of over 70%
•Definition of a technology roadmap, with suitable business models, aiming at commercialisation in 2025

In conclusion, the key objective of validating the technology through testing was achieved during the project while significant progress was made in subsystem and socio-environmental level, in line with the corresponding objectives.

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far

A novel trigeneration system was designed in order to cover all space heating, DHW, cooling and part of the electricity demand of a multi-family building across Europe, based on the energy requirements derived from detailed building simulations, including user behaviour. A small-scale version of the system was then designed and its innovative subsystems (reversible heat pump/ORC, cascade chiller, low-emissions biomass boiler and solar collectors coupled with TEGs) were designed, developed and individually tested in lab conditions.
The developed reversible heat pump/ORC prototypes performed efficiently, especially under solar-assisted operation (COP > 4.5) while ORC operation proved to be efficient under high heat source temperature (> 90 °C) and low heat sink temperatures (< 25 °C). The cascade chiller configuration was made feasible through the indirect hydraulic coupling of the reversible heat pump/ORC to a modified adsorption chiller and COP values up to 5.5 could be achieved.
Referring to the biomass boiler, the implementation of exhaust gas recirculation, air-staging and a new control strategy leads to significant reduction of CO and NOx emissions by over 50 and 25%, respectively, and an efficiency of up to 105%. Using an internal heat exchanger for CHP operation, boiler efficiency exceeded 94%.
Measurements of the first TEG prototypes with the solar collectors showed that for an operation temperature of 120 °C, the TEG system could achieve an efficiency up to 1.7 %. In addition, innovative printed TEGs were developed and tested to investigate the possibility of improving the overall efficiency of the conversion process at a reduced cost.
A smart control strategy based on deep reinforcement learning was developed and its benefits were verified through simulations, especially during winter (reduction of operating cost by 35%) and intermediate season operation.
After individual testing, all the above subsystems were integrated into two prototype systems in Athens and Nuremberg. The systems were tested successfully under all operating modes (space heating, cooling, DHW and electricity supply) in both locations reaching TRL5. Also, simulations in real multi-family houses indicated that a high energy share of around 70% can be achieved, especially in heating-dominated locations.
Finally, a technology roadmap was developed, showcasing the next steps towards further developing this promising technology. This roadmap alongside two videos and communication material showing the project concept and the developed technologies can be found on the project website.

Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far)

A number of advances beyond the state of the art were achieved:

At subsystem level:
•Development of two fully automated reversible heat pump/ORC prototypes with environmental friendly refrigerant which implement an innovative active control of the refrigerant charge in the system. In this manner, the system performance is improved during operation by adapting to the operating conditions through the optimization of the system operating pressures.
•Efficient heat pump performance reaching COPs higher than 4.5 when solar-assisted.
•Development of a cascade chiller configuration of an adsorption chiller and the reversible heat pump/ORC. System performance is sufficient reaching COP up to 5.5 under mild operating conditions.
•The optimisation of the adsorber design has revealed high performance and cost benefit margin compared to state-of-the-art zeolite adsorbers, thanks to the increased adsorbing capacity (~33%), and the reduction of the calcination temperature thus decreasing the manufacturing cost and time.
•Substantial emissions reduction in the biomass boiler through Exhaust Gas Recirculation, air-staging and advanced control. Reduction of CO (70%) and NOx (50%) emissions are reported, with PM emissions far below the authorised limits.
•Boiler efficiency up to 105% is reported under average supply temperatures and up to 94% efficiency under supply temperatures of 110 °C for CHP operation.
•Efficiency up to 1.7% for the first TEG prototypes with solar collectors supply temperature of 120 °C.
•Development of a novel manufacturing method for printed TEGs. A hybrid design on a flexible printed circuit board achieved the highest known normalized power density for an in-plane printed device at 76.1 nWmm⁻²K⁻².

At configuration level:
•Development of an energy system that can cover all space heating, cooling and DHW needs and part of electricity demand. The successful testing in the two prototypes and simulations in real multi-family houses confirmed a total energy share of around 70%, especially in heating-dominated climates.
•Implementation of a smart control strategy based on artificial intelligence enhancing system performance, especially during winter with a reduction of operating cost by 35%.

At life-cycle and societal level:
•Life cycle costing analysis showed that further increasing the pellet energy share by 20% through the control strategy leads to a 15% reduced energy cost compared to the state-of-the-art reference system.
•Identification of key opportunities and challenges for the uptake of SolBio-Rev amongst end users. Dedicated surveys to residential building stakeholders and policy makers were conducted to estimate public acceptance and propose policies for the uptake of the technology.

Athens pilot building

Schematic representation of the SolBio-Rev concept