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Featured Application: Biomass District Heating Systems in Rural Areas. This paper presents a methodology for analyzing the regional potential for developing biomass district heating systems combining forestry biomass and agriculture residues as fuel. As a case study, this methodology is applied to the continental region of Spain. With this analysis the potential for the implementation of biomass district heating systems based on the use of agriculture residues is applied to 501 rural municipalities in Spain. The renewable forestry biomass and agriculture residues resources availability is analyzed and the biomass required for heating is assessed. The results of applying the methodology show the interest of the combination of biomass sources in a relevant number of municipalities with estimated Internal Rate of Return (IRR) values above 10% and for the analyzed region an IRR mean value of 4.3%. [ABSTRACT FROM AUTHOR]

5th Generation District Heating and Cooling systems are promising technologies for using and storing renewable energy generation excess. An annual simulation using data of a location in the south of Spain is carried out to study this context. The novelty of this work is that a common distribution network is used as an energy storage system and integrates the PV electricity excess from the buildings into the 5GDHC system, at ultra-low temperature. The aim is to analyse if it is interesting to use 5GDHC networks, not designed initially for this purpose, to store energy. For the analysed case, it is estimated that 105 MWh of hot thermal energy and 211 MWh of cold energy are stored. This integration of renewable energy excess would reduce 30.2% of the grid electricity consumption by the 5GDHC energy hub, showing the interest of the strategy for balancing the electricity grid. On the other hand, the storage process implies an annual savings of 2.1% in the grid electricity consumption by the energy hub due to the limited thermal inertia of the network. Moreover, the system can store more energy in hours where storage capacity is still available, so its full potential is not being used. • 5thGeneration District Heating and Cooling can be used for storing purposes. • An annual simulation for photovoltaic excess integration is carried out. • 105 MWh of hot thermal energy and 211 MWh of cold thermal energy are stored. • The integration would reduce 30.2% of the grid electricity consumption. • The storage strategy implies savings of 2.1% in the grid electricity consumption. [ABSTRACT FROM AUTHOR]

Biomass heating networks are an efficient and low-emission alternative for rural municipalities without natural gas supply. One of the main challenges for their implementation on a larger scale is to reduce the uncertainty in the profitability evaluation. The linear heat density is the index commonly used to evaluate the potential for heating networks investments. It provides highly accurate estimations in high-density building networks. However, it does not provide accurate enough evaluations for low-building-density networks, resulting in relevant deviations when applied to biomass district heating networks. This work proposes a new index to evaluate the profitability of biomass heating networks in rural environments based on the analysis of investment, operation, and biomass costs. It is developed based on the cost-benefit analysis of biomass heating networks. The new index has been applied to 499 rural municipalities in Spain, showing a high accuracy in estimating the profitability of investments, with R2 values between 0.8179 and 0.9442, compared to 0.2408 if linear heat density was used for the same cases. The analyses show the interest of this approach for the evaluation of biomass district heating potential in areas with dispersed populations. [Display omitted] • Linear Heat Density. • Profiatability Index for evaluating biomass district heating. • Methodology for evaluation district heating systems. • Biomass district heating networks in rural areas. • Viability of biomass heating networks. [ABSTRACT FROM AUTHOR]

The decarbonisation of society requires developing new environmentally friendly solutions for heating and cooling. Ultra-low temperature district heating and cooling (ULTDHC) allows operation with energy sources and systems hard to integrate into previous generations of district networks, making this technology more efficient and sustainable. This work analyses a novel integration of coaxial borehole heat exchangers (CBHEs) to control the temperature of the network, drastically reducing operating costs and emissions compared to existing systems. The concept is analysed based on single and double-loop networks. As a case analysis, it is studied to a ULTDH located in the south of Spain with annual heating and cooling demands of 1045 MWh and 416 MWh, respectively. The single-loop configuration requires more 100 m depth CBHEs connected, 47, whereas the double-loop layout, with a more efficient thermal balance, requires 42. In contrast, it has higher values of annualised costs. The sensitivity analysis of the main parameters proves the system is robust and effective in compensating for external variations. It operates more efficiently in warm/hot regions, increasing the possible applications and implantation expansion. The proposal is useful for new systems and for adapting the existing ones. • An ultra-low temperature network concept balanced only with ground heat exchangers. • The novel proposal drastically reduces operating costs and emissions. • Two base layouts are studied in the South of Spain, requiring 42 and 47 boreholes. • An annualised cost of 103.8 k€ is obtained with the long-term simulation. • Analyses show a more efficient performance in warm/hot regions. [ABSTRACT FROM AUTHOR]

Heating and cooling are responsible for 70% of energy consumption in European buildings, with renewables covering only 18%. To reduce emissions in the building sector, district heating based on low-carbon energy is identified as a key technology for the transition to a low-carbon economy. However, currently only 16% of thermal district networks are based on biomass, and around 3.2% on solar. This paper analyses the application of solar and biomass district heating systems in the low-to-moderate population density areas of the Mediterranean. These areas are characterised by high solar and biomass availability, and lack of space restrictions, along with particular challenges for implementation. A methodology for viability analysis and optimised integration is presented. The methodology is applied to a case study in the south of Spain. The results show that with a linear heat density greater than 1.5 MWh/m, there could be viability with internal rates of return higher than 7.4 and 9.8%, and payback period below 13 and 10 years, for solar and biomass systems respectively. The use of seasonal thermal energy storage allows the solar fraction to be increased from 55 to 75%. Sizing and design strategies for their viable implementation in Mediterranean areas are extrapolated from the analyses. [ABSTRACT FROM AUTHOR]

Biomass district heating systems are an optimal economic and environmental solution for generating and distributing thermal energy. One of the main challenges for a broader development of these systems is the complexity of its implementation in the absence of established regulations in the legal, commercial, technical, or economic fields, a situation that occurs in geographical areas with early experience. This work proposes a model for the sustainability of biomass district heating systems, including the whole value chain, taking into account the role of the stakeholders. The design of this Biomass Universal District Heating (BioUnivDH) optimises the implementation and sustainability of the district heating system in geographical areas with early experience. It is conceived to identify implementation barriers and to contribute to their elimination. The model identifies the stakeholders of the project through the analysis of their relationships, objectives, and expectations. This model allows comparison between different systems, and it improves the decision-making process with a holistic approach that identifies strategies for successful implementation and operation based on economic, environmental, and social acceptance criteria. Finally, to show the application of the BioUnivDH model, it is applied in four heating system projects based on biomass and implemented in four Spanish cities. • Model for sustainability evaluation of biomass district heating. • Methodology for evaluation district heating systems. • Biomass district heating networks in rural areas. • Case study in the continental region of Spain. [ABSTRACT FROM AUTHOR]