Biomass Heating Research Articles

Experimental Study on a Solar Energy–Multi-Energy Complementary Heating System for Independent Dwellings in Southern Xinjiang

This study proposes a multi-energy complementary heating system that uses solar energy combined with biomass energy as the main heat source, with electricity as an auxiliary heat source. The system aims to tackle the low efficiency, high energy consumption, and pollution associated with traditional heating methods in rural southern Xinjiang, enhancing performance and productivity. It is designed to operate in five modes based on the region’s climate and building heat load requirements. An experimental platform was set up in eight rural households in Tumushuk City, Xinjiang, where winter heating tests were conducted. The goal of this study was to analyze the economic and environmental benefits of the system. The results showed that the energy utilization efficiencies of the five modes were 56.84%, 74.34%, 70.1%, 63.13%, and 59.68%. The corresponding CO2 emissions were 3.56 kg/d, 45.09 kg/d, 105.75 kg/d, 30.97 kg/d, and 76.79 kg/d. The environmental and economic costs for each mode were 0.0493 USD/d, 0.6398 USD/d, 1.5029 USD/d, 0.4384 USD/d, and 1.0905 USD/d. It is clear that as an auxiliary heat source, biomass energy is more beneficial than electricity. All five modes maintained indoor temperatures of 18 °C or higher, meeting winter heating needs in cold regions. The results of this study provide important data support for the promotion and application of solar and biomass heating systems in the rural areas of southern Xinjiang and also provide valuable references for solving the problem of decentralized heating in rural areas.

Research on the Construction Method of an Assembly Knowledge Graph for a Biomass Heating System

In the complex process of assembling biomass heating systems, traditional paper documents and construction process card management methods have weak information correlation and take a long time for information retrieval, which seriously restricts the assembly efficiency and quality. Moreover, the assembly process involves numerous components and complex processes, making it difficult for traditional management methods to cope with. To address this issue, a knowledge graph-based assembly information integration method is proposed to integrate scattered assembly information into a graph database, providing pathways for accessing assembly information and assisting on-site management. The biomass heating system assembly knowledge graph (BAKG) adopts the top-down method construction. After the construction of the upper schema layer, the 3DXML file was parsed, the XML.dom parser in Python3.7.16 was used to extract the equipment structure information, and the RoBERTa-BiLSTM-CRF model was applied to the named entity recognition of the assembly document, which improved the accuracy of entity recognition. The experimental results show that the F1 score of the RoBERTa-BiLSTM-CRF model in entity recognition during the assembly process reaches 92.19%, which is 3.1% higher than that of the traditional BERT-BiLSTM-CRF model. Moreover, the knowledge graph structure generated by the equipment structure data based on 3DXML file is similar to the equipment structure tree, but is more clear and intuitive. Finally, taking the second-phase construction process records of a company as an example, BAKG was constructed and assembly information was stored in the Neo4j graph database in the form of graphs, which verified the effectiveness of the method.

Enhanced Biomass Combustion via Bluff Body- and Impingement-Stabilized Natural Gas-Air Premixed Flames

ABSTRACT The preheating, flow recirculation and impingement effects of trapezoidal bluff bodies increased the biomass heating value-based combustion efficiency to 94% at a firing intensity of 78 MW/m3. A sawdust-laden air stream was combined to bluff body-stabilized natural gas-air premixed flames in three different configurations. A common impingement of opposing fuel-lean mixture jets with a sawdust-laden air cross-flow upstream of a solid bluff body provided a peak turbulent kinetic energy of 11.8 m2/s2. Using opposing jets with ports of multiple sharp corners minimized the flame length/combustor diameter ratio to 4.2. The combination of premixed flame impingement on the combustor base with the flow stagnation effect inside hollow bluff bodies provided a maximum blow-off velocity of 19.5 m/s at Ф = 0.8. Delaying the biomass interaction with the premixed flames decreased the peak exhaust NOx concentration to 0.17 g/kW.hr. Confronting the premixed flame jets by the sawdust-air laden jet provided a superior flow configuration in which the premixed flame high temperatures provided effective tar cracking, thus minimizing the exhaust total tar content to 50 mg/Nm3. A simultaneous peak exhaust soot volume fraction of 7 × 10−8 and a peak exhaust CH4 concentration of 0.1% were thus combined to a peak CO concentration of 14 mg/MJ.

Advancing Heat Pump Adoption in Ukraine’s Low-Carbon Energy Transition

The European Union established a legislative framework to facilitate the transition to low-carbon energy sources. As Ukraine aspires to join the EU, it is progressively adopting similar legislation. The extensive damage to Ukraine’s fossil fuel-based heat generation infrastructure necessitates the reconstruction of heating and cooling supply systems, with a focus on low-carbon energy sources, particularly heat pumps. Notably, Poland achieved the highest growth in installed heat pump capacities in Europe, offering valuable insights for Ukraine’s energy transition. This study employs the TIMES-Ukraine model to assess the potential proliferation of heat pumps within the country. The findings suggest that, if capital costs for heat pumps decrease, their adoption could accelerate more rapidly than biomass-fired heating systems, particularly in urban single-family homes and buildings lacking central heating systems, over the next decade. While high investment costs may slightly diminish the attractiveness of this technology for space heating, heat pumps consistently outperform biomass heating appliances and potential biomethane-sourced gas boilers.

Optimal control framework for cost-effective, intelligent, renewable energy-driven communities in Norway, enhanced by ANN and grey wolf method

The present work introduces a novel yet smart energy system to decarbonize the energy mix, provide cost-effective green energy, and help to achieve sustainable energy production/storage/usage. Smart hydronic units and multiple controllers are the backbone of this idea, which aims to monitor energy conversion among components, the grid, and users through an innovative rule-based framework. This clever integration results in smaller components, bidirectional grid connection, and increased penetration of renewable energy sources into the local energy network. The system is driven by photovoltaic thermal panels and a biomass heater integrated with a heat pump and internal combustion engine. The TRNSYS-MATLAB framework evaluates the system's practicality from all aspects. Multi-objective optimization based on the grey wolf approach equipped with artificial intelligence is added to find the most optimal state. Compared to the conventional system in Norway (hydropower + wind), the proposed smart integration achieves up to 55 % and 5.4 % reduction in energy costs and emission index. In particular, the carbon emission index is lowered to 36.3 g/kWh, and the energy cost is decreased to 38.4 $/MWh. Also, the parametric analysis indicates a conflictive change among key metrics when altering a variable, necessitating the multi-objective optimization to achieve a balancing trade-off. The optimization reduces the emission index, investment cost, and energy cost by about 1.8 g/kWh (5 %), 156,000 $/year (2.5 %), and 1.5 $/MWh (4 %) while improving the efficiency by about 1.7 % compared to the design condition. The suggested system generates 17,830 MW/year of clean energy and can mitigate carbon dioxide emissions by 552,000 kg per year compared to the Norwegian energy mix.

Techno-economic analysis of hybrid solar-assisted geothermal and biomass heating systems in remote subarctic communities (Nunavik, Canada)

The Nunavik region mainly relies on fuel-oil for their heating needs, leading to high energy costs and sustainability issues. Studies focusing on renewable heating alternatives in remote Canadian regions are limited and have been evaluated under different models and methodologies. This work studied several heating alternatives to meet the heating needs of a building in Nunavik, Canada, to reduce the dependence on fossil fuels, the amount of greenhouse gas emissions, and overall heating cost. Studied alternatives include biomass furnace and solar-assisted geothermal heat pumps, which were compared to fuel-oil #2 heating. A 50-years life cycle cost (LCC) analysis was carried out for each alternative considering environmental, technical, and economic issues. A strategy of net metering obtaining credits/revenue by injecting PV electricity into the local grid was considered. The LCC analysis shows that a mix of heating systems represents an interesting alternative for Northern Québec with a levelized cost of energy that varies from 0.23 to 0.62 $/kWh, reducing emissions up to 18.9 tons of CO2eq/year. Conventional heating oil system has a comparable cost of 0.20 $/kWh after fuel-oil subsidy and 0.26 $/kWh before subsidy. Results could eventually be extended to similar subarctic settings in Canada and worldwide.

Thermodynamics and economic analysis of a two-stage desiccant cooling (TSDC) system based on biomass heating used for greenhouse application

Thermodynamics and economic analysis of a two-stage desiccant cooling (TSDC) system based on biomass heating used for greenhouse application

Environmental, economic, and eco-efficiency assessment of residential heating systems for low-rise buildings

Transitioning from fossil fuels to renewable heating is essential for rapidly reducing greenhouse gas emissions. Besides greenhouse gas emissions, other environmental and economic impacts are crucial for successfully implementing renewable heating systems. This study evaluates 13 residential heating systems' environmental, economic, and eco-efficiency performance for a typical German two-story dwelling. The life cycle assessment method is employed to quantify the environmental impacts. Assuming a sustainable supply of biomass-based fuels, biomass heating systems exhibit the lowest environmental impacts, whereas gas heating systems are associated with high environmental impacts. Among heat pump systems, the water-source heat pump demonstrates the lowest environmental impact. Additionally, integrating a PV system into heat pump systems reduces the environmental impacts across all heat pumps. The evaluation indicates that the air-source heat pump is the most economical system, while the pellet boiler with solar thermal support and the heat pump with ice storage incur the highest costs. However, the cost differences among the heating systems are relatively small, making it challenging to establish a clear ranking based solely on economic evaluation. An eco-efficiency assessment, which combines environmental and economic aspects into a single indicator, reveals that the most eco-efficient systems are the air-source heat pump, both with and without a PV system, and the wood gasifier heating system. In contrast, the ice-storage heat pump and the pellet heating with solar thermal support show the lowest eco-efficiency.

A new approach to evaluate the overall heat transfer coefficient of a fluidized bed biomass pyrolyzer

The heat transfer characteristics of non-pretreated rice husk pyrolysis in a fluidized bed with alumina beads (500 μm - 590 μm) as bed material are studied. Assuming instantaneous heating of biomass to the reaction temperature, the effective overall heat transfer coefficient of the system (UA) is initially calculated based on the compositions of the collected products and reaction temperature. UA ranges from 0.82 to 2.95 W/K. This heat transfer coefficient study allows ad hoc product distributions to be predicted from theoretical bases. The effects of the biomass feeding rate (F) and the bed height (H/D) on UA values are also analyzed. Highest UA and specific heat of the pyrolysis reaction of −3.35 MJ/kg are found at F = 5 g/min and H/D = 1.0, where H/D is the largest and F is the lowest in the range studied. Upon feeding of the low thermal conductivity biomass, UA typically decreases. However, if the bed materials are limited, the fed biomass and its produced char act as an auxiliary heating medium to improve the effective heat transfer coefficient. High UA improves the efficiency of the pyrolysis reaction, but it decreases the bio-oil fraction in the product due to secondary decomposition.

Estimation of wood biomass boiler use in cold climate regions on CO2 emissions of light-frame timber structure

Considering Nagano City, as the cold climate region of Japan, the annual heating load was simulated using a model of a two-story timber structure. The results of simulations were used to compare the CO2 emissions according to the energy consumption of five methods of heating as well as primary and secondary energy sources. Actual data from power and gas companies in Nagano and Japanese energy standards were used for the estimations of CO2 emissions of electric heat pump air conditioners, LNG-powered city gas boilers, LPG boilers, kerosene stoves, and wood biomass boilers using pellets as an energy source. Wood biomass boilers showed CO2 emission savings of up to 85 %, 75 %, 75 %, and 76 %, respectively. The operating and equipment costs were estimated based on secondary energy calculations. The kerosene stove had the lowest cost, but CO2 emissions were lowest in the case of using pellet boilers for 30 years. These results clearly show the potential and merit of pellets used in wood biomass boilers as a renewable energy source when compared to fossil fuels. In addition to the CO2 reduction capabilities, the low operating costs of wood biomass heating systems incentivize their use in cold climates.

Effects of steam feeding on microwave heating of cellulose with magnetite used as susceptor

Microwave heating (MWH) of lignocellulosic biomass with susceptors has attracted attention for H2 production. In this study, H2 is produced from cellulose via MWH at 800 °C in a steam atmosphere with magnetite used as the susceptor. The effects of steam feeding and MWH on the product yields are experimentally investigated in comparison with conventional heating (CH). The H2 and CO2 yields are increased by steam feeding for both MWH and CH because the water–gas shift reaction occurs. Without steam feeding, MWH enhances H2 and CO production, thereby increasing the maximum energy efficiency. With steam feeding, the steam gasification of C is more predominant for CH than for MWH as the reduction in the C content in the char of CH is higher than that of MWH. MWH reduces the formation of secondary char, and it is therefore expected to overcome issues such as the clogging or blockage of gas lines.

WITHDRAWN: Optimizing smart building energy systems for sustainable living: A realistic approach to enhance renewable energy consumfaption and reduce emissions in residential buildings

The presented a groundbreaking and economical approach to enhancing the sustainability of residential buildings by optimizing smart building energy systems. This approach, which is instrumental in advancing the shift towards a sustainable future, focuses on maximizing occupant comfort while markedly diminishing the energy footprint and emissions of the built environment. The study offers a comprehensive techno-economic and environmental analysis of the system performance conducted on residential apartments in Baghdad, Iraq. The results are promising, showing that the system successfully transfers 75.6 MWh of renewable electricity to the local grid and utilizes an additional 120.42 MWh for the internal needs of the building and operation of electrical components. A key component of the system is the biomass heater, which meets over 70.2% of the heating demand, proving particularly effective during periods of low solar power availability and high electricity costs. This highlights the importance of integrating diverse energy sources to reduce dependence on the grid. The results also reveals that the costs associated with energy consumption are substantially offset by the revenue generated from selling excess renewable energy during high-production periods. This results in average monthly energy costs being maintained below $151.2/MWh over several years. This cost-efficiency is achieved by eschewing batteries and optimizing the dimensions of the heat pump. Additionally, the system demonstrates a low emission index of 12.85 kgCO2/MWh, indicating a potential reduction in CO2 emissions by 75.6 TCO2/year compared to traditional energy mixes.

Seasonal energy performance assessment of a hybrid HVAC system driven by solar and biomass energy for space heating and cooling in residential buildings

The H2020 project Hybrid-BioVGE aims to develop a sustainable HVAC system concept for buildings’ climatisation entirely based on renewable energy sources. The Hybrid-BioVGE system provides space heating/cooling and DHW production of small- and medium-scale buildings and deploys solar and biomass heat as energy inputs. During the heating period, thermal energy is provided directly by solar thermal collectors and a biomass boiler. The cooling energy demand is met by a thermally-driven ejector cycle based on a Variable Geometry Ejector (VGE), which adjusts its geometry according to two degrees of freedom. A demonstrator of the Hybrid-BioVGE system was designed and installed in a residential building in Porto (Portugal). The demonstrator’s seasonal energy performance was assessed numerically by a simulation model implemented in TRNSYS. Simulation results show that up to 98% of the system energy input is provided by renewables during the heating season, with a solar fraction higher than 60%. Conversely, the system energy performance is lower than expected during the cooling season due primarily to the limited performance of the heat rejection loop.

Comprehensive evaluation on performance and local impact in energy, environment, and economy of different rural clean heating modes: A case study in Northeastern China

To improve the atmospheric environment, the clean heating projects such as “coal-to-electricity” and “coal-to-gas” have been implemented in China, while leading to significantly increase in heating costs for rural residents and the supply pressure of fossil fuels in some rural areas. As the local renewable energy, biomass briquette can be used for rural heating. However, the local resource feasibility for the biomass heating has not been paid enough attention to, besides, the performance and potential local impacts of different heating modes has not been comprehensively estimated. Based on multiple attribute decision-making, this paper proposes an evaluation system by integrating the performance comparison and local impact in energy, environment, and economy, especially including an assessment on local biomass resource feasibility. The clean heating modes of biomass, electricity, and gas are evaluated along with the current coal heating mode in Harbin and Qiqihar as case studies. Results show that in the case regions, the biomass mode has sufficient resources and achieves significant comprehensive benefits, with the relative proximity nearly twice that of the coal mode. All the three clean heating modes can achieve environmental benefits. Due to the best economic feasibility, the biomass mode is suitable for the current rural economic level, with the cost intensity of 0.01 yuan/MJ, and the ratio of heating cost to disposable income less than 1%. The electric mode hardly produces comprehensive benefits because of the high cost. The gas mode is the least recommended due to significant energy demand and great economic burden.

Game theory-based analysis of policy instrument consequences on energy system actors in a Nordic municipality

The transition of energy systems requires policy frameworks and instruments to make both energy suppliers and consumers contribute to the common goal of emission reductions and to fairly allocate costs and benefits among market actors and the government. Assuming that market actors – suppliers and consumers adhering to their economic interests – would benefit from cooperating to mitigate emissions, this study applies a game theory-based approach to investigate the interaction between a local electricity supplier and a group of heating consumers not connected to district heating. Selected policy instruments are tested, and their consequences are analyzed in the context of a representative Nordic municipality. The results show that the auction-based Contract for Difference policy instrument is the most suitable one in the studied Nordic context to achieve significant levels of CO2 emissions reduction. It creates a higher level of strategic interaction between the actors, that would be lacking otherwise, under the form of transfer payments from consumers to supplier, and avoids costs to the general taxpayer. While this is sufficient to promote the investments in renewables by the supplier, additional subsidy policies are required to enable the heating consumers to invest in more capital-intensive energy efficiency measures or biomass heating.

Microwave dielectric characterization and loss mechanism of biowaste during pyrolysis

The effectiveness of microwave heating of biomass depends on the changes in dielectric properties. This study systematically investigated the microwave dielectric properties and loss mechanism of biowaste at different frequencies (915 and 2,450 MHz) and temperatures (25–800 °C) using the cavity perturbation method. The gas emissions and properties of the biochar produced during pyrolysis were characterised by SEM, XRD, and TG-FTIR. The findings revealed that the dielectric properties and penetration depth of the biomass and biochar changed significantly during microwave pyrolysis. The dielectric constant and dielectric loss coefficient first increased and then decreased during the drying stage, and they decreased continuously with the volatile’s generation in the pyrolysis stage, while the formation and high conductivity of biochar promoted a sharp increase in dielectric properties during the carbonisation stage. The loss tangent angle is 0.01–0.05 in the first two stages, while it increased to 0.10–0.25 in the carbonization stage, demonstrated that the biowaste is a low-loss material. However, the microwave absorption capacity was enhanced for pyrolyzed biochar. The loss mechanism revealed that dipole polarisation primarily contributes to the dielectric loss during the drying and pyrolysis stages, whereas interfacial polarisation plays an important role during the carbonisation stage. The data provided in this paper contribute to the evaluation of microwave penetration depth in biomass and the design of large-scale microwave-based heating systems. Furthermore, this study offers a theoretical basis for modelling and simulating the microwave heating of biomass and achieving efficient energy conversion.

Potential assessment of biomass-based single-stage adsorption systems for refrigeration, cooling, and heat-pumping applications

ABSTRACT This article presents the performance estimation of a single-stage vapor adsorption system employing various carbon-based adsorbents with ethanol refrigerant, coupled with a small-scale biomass-based heating unit for space cooling, refrigeration, and heat-pumping applications. A detailed parametric investigation highlights the effects of operating temperatures, and heat exchanger to adsorbent mass ratio on specific cooling energy (SCE), coefficient of performance (COP), uptake efficiency (ηu), and mass of adsorbent to combustion fuel (mad/mcf) to identify the suitable adsorbent and sorption bed designs for each application. The numerical findings reveal that the flat-finned tube (FFT) adsorber outperforms traditional-finned tube (TFT) and tube & shell-type (T&S) adsorbers, achieving 19% and 30% higher COP, respectively, with biomass carbon-ethanol pair. The H2-treated Maxsorb-III shows the greatest optimal cooling COP (0.73), followed by the biomass-carbon (0.72) for refrigeration and space cooling. For heat pumping applications, biomass carbon-ethanol achieves the highest heat pumping COP (1.84) at a desorption temperature of 90°C, surpassing H2-treated Maxsorb-III. Further, the biomass-derived activated carbon requires the lowest amount of adsorbent per unit mass of combustion fuel in the biomass heating unit. The present thermodynamic analysis is a precursor for optimization of the potential heat-exchanger geometries and operating parameters, with the high-performance carbon adsorbents.

Flue Gas Recirculation System for Biomass Heating Boilers—Research and Technical Applications for Reductions in Nitrogen Oxides (NOx) Emissions

The paper discusses the results of investigations of the change in thermal and emission-related parameters of a heating boiler fueled with biomass after a modification with a proprietary flue gas recirculation system made for this type of equipment. The results provide insight into the combustion process with a multistage flue gas recirculation that materially affected the boiler operation: a reduction in the mass concentration of nitrogen oxides (NOx) by reducing the combustion temperature. The authors also observed a reduction in the emission of particulate matters (PM) and carbon monoxide (CO). For the investigations, the authors used a heating boiler fitted with an automatic fuel feed (timber pellets) and a proprietary patented flue gas recirculation system (Polish patent Pat. 243395) for low power solid fuel heating boilers. Aside from the measurement of the mass concentration of the emitted pollutants, the research focused on the measurements of the temperature inside the combustion chamber, the temperature of the flue gas and the level of oxygen in the flue gas. The aim of the research was to confirm the validity of using the flue gas recirculation technique to reduce emissions of harmful substances from biomass heating boilers, as a technique not previously used for this group of devices. Moreover, the aim of the research was to test an original engineering solution, in the form of a flue gas distribution valve, and investigate its effect on reducing NOx emissions and improving other thermal and emission parameters of the boiler. The obtained research results confirm the validity of the chosen actions and provide a positive premise for the practical use of this technology in solid fuel heating boilers.

Concept Design of the WRB-6 Water-Tube Boiler with a Stepped Grate and a Furnace for Burning Straw Bales in a Cigar System

The article presents the conceptual design of the solid fuel from the forest and sawmill production waste and agricultural waste biomass-fired water boiler. The project was supported by thermal and flow calculations. The designed WRB-6 boiler is a 3-pass unit with a fully screened furnace chamber and is equipment of a local biomass heating plant. It is fired with biomass, transported over no more than 30 km. The furnace has a double function – dual fuel. Both fuels can be burned simultaneously or alternately, depending on seasonal availability. In the front part there is a channel for feeding and burning large bales of cereal straw. The lower closure of the chamber is a mechanically inclined grate for the combustion of wood biomass in the granulation of chips. As part of the work, calculations of the amount of biomass fuels possible to be obtained on the local market with economy of delivery were also performed. As a result of the calculations, the temperatures of water and flue gas at the outlet, boiler efficiency, slagging and impurity indices for biomass were also presented.

Energy, exergy, environment and techno-economic analysis of hybrid solar-biomass systems for space heating and hot water supply: Case study of a Hammam building

The main goal of this study is to assess the thermodynamic performance, environmental benefits and economic feasibility of using a new hybrid solar-biomass system (HSBS) for the production of domestic hot water at 60 °C and for the provision of space heating via an underfloor heating system in a Hammam building located in Marrakesh-Morocco. The HSBSs consists of small biomass pellet boilers in combination with three types of solar thermal systems (evacuated tube, flat plate and parabolic trough collectors). A TRNSYS simulation model of a biomass heating system was developed and validated against experimental data. Performance comparisons of the biomass system with various optimal HSBSs were then conducted, and their results evaluated in terms of energy, exergy, environmental, and economic perspectives. Comparisons between various collectors’ technology revealed that the optimum collector areas of 204 m2, 224 m2 and 300 m2 are responsible for the lowest Levelized Cost of Heat (LCOH) corresponding to about 0.0755 $/kWh, 0.0696 $/kWh and 0.0642 $/kWh when using PTC, FPC and ETC, respectively. Furthermore, the optimal HSBS with evacuated tube collectors is the most effective configuration with a solar fraction of 57 %, and a total life-cycle saving cost of 0.509 M$ for a total annual heat demand of 533 MWh. Moreover, the total energy and exergy efficiencies are calculated equal to 40 % and 3.9 %, respectively. The payback period is found to be around 4.9 years, the levelized cost of heat 0.0642 $/kWh, while the annual CO2 avoidance amounts to 656 tons.