Renewable Heating Technologies Research Articles

Combining expansion turbines, heat pumps, and low-temperature solar heat for enhanced primary energy savings in gas pressure regulating stations

According to previous studies, gas pressure regulating and metering stations (GPRMS) in Germany account for a primary energy consumption between 1.4 and 2.0 TWh/a for the preheating of natural gas flowing through. This work assesses the potential of reducing this consumption through the combined use of expansion turbines, heat pumps, and solar thermal collectors. For this purpose, operation data of 57 GPRMS of a German gas network operator are used to design systems combining in different scenarios two and three of these technologies in each GPRMS. Using an in-house model developed in Python the 57 systems are simulated over one year with an hourly time step. The results show a potential for the installation of expansion turbines with a total capacity of 3.57 MWel, leading, combined with the renewable heating technologies, to a reduction of more than 99 % of the original gas consumption for gas preheating. The results are then extrapolated to the whole country using scaling factors, showing a potential for feeding-in between 510 and 1,140 GWh/a of surplus electricity into the grid, on top of the almost complete elimination of the gas consumption for gas preheating. In total, the use of the complete technical potential available would lead to net primary energy savings between 1,710 and 3,650 GWh/a and net CO2-emission reductions between 470 and 1,010 kt/a. Overall, this work demonstrates that the combination of expansion turbines and heat pumps technically allows an almost complete decarbonation of the operation of GPRMS in Germany. In addition, significant amounts of electricity could be fed into the grid, especially during the winter months, which would contribute to decarbonise the electricity mix of the country. The amount of electricity fed into the grid can be increased with the additional use of low-temperature solar thermal systems. To exploit this potential in the future, current regulations should be adapted and targeted support programmes launched.

Hybrid Technologies for Water Heating Applications: A Review

The over-reliance on fossil resources necessitates the development of a sustainable energy system. Renewable energy and efficient hybrid water heating technologies are viable net-zero energy options. The economic benefits of these hybrid technologies offer a promising prospect for widespread adoption in developing countries as a means of increasing the hot water production. These hybrid technologies are becoming increasingly popular for domestic thermal applications in remote areas to compensate for energy shortages. This paper provides an overview of hybrid renewable water heating technologies with a focus on hybrid configurations, optimization techniques, mono-particle, and hybrid nanofluids and modelling. This paper also highlights the prospects for increasing the economic attractiveness and public acceptance of such systems.

The “four Ds” and support for Local Smart Grids: analysis from national surveys in the UK and Canada

Abstract Local Smart Grids are emerging during the climate crisis, as governments and industry recognize the need to better integrate intermittent renewable energy, storage, transportation, heating, and smart technologies. Such projects can represent profound changes to the status quo of energy and citizen lifestyles. They are also being associated with the “four Ds,” whereby Local Smart Grids are decarbonizing, decentralizing, digitalizing, and potentially democratizing energy systems. Yet, due to their recent arrival, there is very little social scientific research that has aimed to better understand public views, expectations, and support for this change. We attempt to fill this important gap in the literature through the analysis of two nationally representative surveys in the UK (n = 3034) and Canada (n = 941). This analysis highlights within- and between-country trends, including how the variation in responses regarding the “four Ds,” demographic factors, and other variables may explain the differences we see in terms of support for energy system change in the UK and Canada. Our analysis also shows that there are common elements, including the importance of the decentralization, and especially the democratization of energy in shaping support. We hope that this study will help governments, industry, community groups, and local residents themselves in both countries come together to advance the kind of Local Smart Grids that address climate change and represent a supported, just energy transition.

Modelling and Experimental Characterisation of a Water-to-Air Thermoelectric Heat Pump with Thermal Energy Storage

Nowadays, increasing the penetration of renewable heat technologies is an important approach to minimise global primary energy use and reduce CO2 emissions for a sustainable future. Thermoelectric heat pumps, which have some unique characteristics in comparison with conventional vapour compression heat pumps, can be integrated with solar thermal energy storage to form a promising renewable heat technology. However, currently, a reliable numerical model for TeHPs suitable for building energy simulation is lacking and the benefits achievable for a TeHP thanks to the integration with heat storage are unclear. To solve these issues, in this work, an experimental apparatus consisting of a water-to-air TeHP unit with a heat storage tank is modelled and tested for the first time, under the scenarios with thermal energy storage and without thermal energy storage, respectively. The results found that the developed numerical model could well predict the output performance of the TeHP unit, with deviations within 12%. Additionally, the output performance of the TeHP unit when combined with a heat storage tank is better than that of the TeHP unit without heat storage, in terms of the maximum temperature achieved in the testing box, the temperature response speed of the testing box, and the coefficient of performance (COP) of the TeHP unit. This work not only paves the way for the following building-integrated simulations of TeHP units, but also provides guidance for the design of the integrated systems that include TeHPs and thermal energy storage.

State Mandates on Renewable Heating Technologies and the Housing Market

<h3>Abstract</h3> We study the effect of a state level mandate on renewable heating technologies on the housing market. The mandate requires a minimum share of 10 % renewable energy sources when changing the heating system in the existing building stock. The mandate could lower the relative price of homes in the existing building stock. We implement a two stage difference-in-differences nearest neighbor matching approach to identify the effect on prices taking advantage of differences in regulation by location and vintage of the building stock. We find no evidence of a negative effect of the mandate on housing prices.

Modelling barriers to low-carbon technologies in energy system analysis: The example of renewable heat in Ireland

While there is a rich body of literature on the wide range of barriers to investment in renewable energy technologies, little guidance exists on how to integrate the barriers into energy systems modelling. The present study develops a prototype to represent barriers such as risk perceptions and inertia in energy systems analysis. Employing a techno-economic model that describes the deployment of renewable heating technologies in Ireland, our results show the methodological importance of the representation of heat-users’ decision making process in energy systems analysis. Implications in promoting renewable heat, market development and regulation are discussed.

Does the stick make the carrot more attractive? State mandates and uptake of renewable heating technologies

Command and control regulation is a popular tool for mitigating greenhouse gas emissions from the building stock. We exploit the introduction of a state-specific mandate in Germany on renewable heating when replacing the heating system in existing homes. We study the effect of the mandate on the uptake of subsidies for renewable heating technologies using unique data from a pre-existing federal government subsidy scheme. Using a geographic discontinuity design, we find that the mandate has positive effects on take-up of these subsidies, with 2 additional subsidized installations per 1000 eligible buildings in the existing building stock on average. Effects are larger in municipalities where adoption rates as measured by the subsidy scheme were below median prior to the introduction of the mandate. However, we also find suggestive evidence that retrofitting activities in the state declined in response to the introduction of the mandate.

Stakeholder Involvement for Sustainable Energy Development Based on Uncertain Group Decision Making: Prioritizing the Renewable Energy Heating Technologies and the BWM-WASPAS-IN Approach

This paper proposes a multi-criteria decision framework for promotion of the heating systems based on the renewable energy sources. The objective and subjective data are taken into consideration by the virtue of the relevant quantitative techniques. The paper integrates the Best-Worst method (BWM) and modifies the Weighted Aggregated Sum Product Assessment (WASPAS) method. The BWM is utilized for eliciting the weights of the criteria during the expert survey. We apply the interval-normalized WASPAS for the multi-criteria ranking of the heating technologies. Thus, the uncertainty is taken into consideration. The empirical application deals with the case of Lithuania where modernization of the heating system is rather important in order to reduce energy poverty and increase the quality of life. Three heating technologies (i.e. heat pumps, solar heating and wood pellet boilers) are assessed through the expert survey and multi-criteria evaluation methods. The multi-criteria analysis suggests wood pellet boilers and solar heating dominate the heat pumps in terms of the overall utility and could be promoted as the most suitable renewable heating technologies.

A Mixed-unit Input-output Model for Renewable Heat Technologies: an Application to Employment Impact Assessment

A Mixed-unit Input-output Model for Renewable Heat Technologies: an Application to Employment Impact Assessment

State Mandates on Renewable Heating Technologies and the Housing Market

We study the effect of a state level mandate on renewable heating technologies on the housing market. The mandate requires a minimum share of 10 % renewable energy sources when changing the heating system in the existing building stock. As renewable energy sources are still more expensive than conventional alternatives this mandate could lower the relative price of homes in the existing building stock when a replacement of the heating system is impending. We implement a two stage difference-in-differences nearest neighbor matching approach to identify the effect on prices taking advantage of differences in regulation by location and vintage of the building stock. Our results find no evidence of an effect of the mandate on housing prices.

Making a Case for Local Combined Head and Power and District Heating Infrastructures within the United Kingdom Policy Landscape

Planning energy infrastructure at the local level is the key to addressing some of the most difficult challenges in climate change and energy policy planning (i.e. fuel poverty) and to unlock the transformative potential of distributed energy technologies. The scientific field of urban energy and carbon modelling is becoming a fundamental instrument to estimate an energy and carbon baseline at a point in time and to quantify the impact that policy-driven technological interventions that could have on the overall carbon footprint of a city. This capability enables an evidence-based approach in which the economic case towards a low-carbon economy can be made. Transformative local distributed energy technologies such as CHP or district heating have a strong spatial component due to a need to identify synergies with adjacent properties or heating loads. Currently available domestic building energy models often do not take into account spatial information. Accessing geo-referenced data for energy modelling can also be particularly useful as validated outputs (i.e. heating and electricity loads, energy profiles) can be mapped using spatial modelling techniques that help to easily identify high and low energy consumption areas and potential synergies in local energy infrastructure planning. In Newcastle upon Tyne UK, the council is exploring the opportunities for the installation of renewable heat technologies on their own stock as a matter of urgency. Identification of potential sites and feasibility for technical and financial applicability within the UK policies will be addressed by this paper.

A review of water heating technologies: An application to the South African context

Abstract The process of water heating consumes enormous amounts of energy. South African households may see up to 40% of their total energy be allotted to the heating of water. The implementation of energy efficient or renewable energy source technologies, for the main purpose of heating water, may assist in reducing the magnitude of the energy crisis that South Africans are facing daily. This will, in turn, reduce energy consumption and costs, so that the energy price hikes do not affect the consumers as severely as it would otherwise. The purpose of this paper is to provide a survey of the most frequently used domestic water heating technologies. The paper aims to critically analyse and summarize recent advancements made in renewable and non-renewable water heating technologies, particularly in the South African case. These technologies include the electric storage tank water heater, solar water heaters (passive and active circulation), heat pump water heater, geothermal water heating, photovoltaic-thermal water heater, gas-fired tankless water heater, biomass water heater and oil-fired water heater. Substantial research works and other academic studies focusing on efficiency improvement, optimal design and control, were consulted and categorized in terms of contributions, focus and respective technologies. The key findings of the review conducted on the various water heating technologies are discussed and organized, based on the advantages, drawbacks, approximate initial investment, average life expectancy and payback period. The results of this survey identify gaps in existing research. The aim is to propose a new perspective on the importance of energy efficient hybrid water heating systems and the cost savings they might offer.

Building heating solutions in China: A spatial techno-economic and environmental analysis

Fast urbanization process and promotion of life standard in China requires a great amount of energy input in building heating sector. North China now faces challenges of upgrading existing fossil fuel based high emission district heating systems into more environmental friendly heating systems. South China is discussing to choose proper building heating solutions for new and existing buildings which lack proper heating facilities. Renewable heating technologies such as ground source heat pump and air source heat pump are candidates to upgrade traditional heating solutions such as fossil fuel boilers and electric heaters. In order to find the most feasible building heating solution for different geolocations of China, this paper proposes a spatial data based techno-economic and environmental analysis methodology to fulfill such research gap. Case studies are carried out in two selected cities by using proposed methodology. Evaluation model shows that, heat pumps is quite competitive in south China compared with electric heaters, whereas in north China heat pumps have to reach several preconditions to be competitive with coal boiler district heating system under current techno-economic and environmental situations. In north China, a heat pump should reach a minimum seasonal coefficient of performance of 2.5–3.7 (for ground source heat pump) or 2.7–3.0 (for air source heat pump) to become CO2 and PM2.5 emission neutral as well as economically competitive compared with coal boiler district heating system. The advantage of proposed methodology is its simplicity in execution and could be repeated to other areas as the data required are available.

Using multi‐criteria analysis to prioritize renewable energy home heating technologies

Replacing all oil boilers with renewable energy technologies by 2035 is part of the national energy strategy 2050 in Denmark. Individual heating is supposed to supply around one-fourth of the total residential heating after 2035. About 205,703 homes will need to replace their current oil boilers. This study investigates the drivers for decision makers when adopting different renewable heating technologies. A total of 11 factors that embrace the economical, technological and environmental aspect of the alternative renewable heating technology are identified, and these were used for the selection of the alternative renewable heating technologies. Three renewable heating technologies: solar heating, heat pumps and wood pellet boilers are used in the estimation. The multi-criteria decision making analysis shows that solar heating is considered as the best alternative, and heat pumps is the second best, wood pellet boiler is the least attractive among three alternatives. It can be noted that solar heating and heat pumps are close alternatives.

Does the Stick Make the Carrot More Attractive? State Mandates and Uptake of Renewable Heating Technologies

In this paper, we investigate the effect of the state-level renewable heating mandate for existing homes in Baden-Wuerttemberg, Germany's third largest federal state. The mandate requires homeowners to supply at least 10 % of their heat demand with renewable energy when they replace their existing heating system. To assess the impact of the renewable heating standard on the uptake of renewable heating systems, we use unique data on a federal government subsidy scheme and exploit geographic differences in state laws over time. We find no evidence of an effect of the mandate even after restricting distance to the state border and refining the data set through matching on population and building characteristics. These findings are unchanged, when we allow effects to vary across space or over time. While energy efficiency and renewable standards are often criticized for not being cost-effective, our results challenge the widespread view that a standard is nevertheless successful in achieving its policy goal.

Biomass from Wood Processing Industries as an Economically Viable and Environmentally Friendly Solution

Biomass is seen as an economically viable and environmentally friendly solution to energy generation. Biomass is a financially viable investment as well as being environmentally friendly. The development and implementation of biomass technologies could bring many environmental, energetically and economic benefits, solving important problems such as waste disposal and renewable energy supply. The different countries clearly have chosen very different approaches in developing and deploying various bio–energy options. Partly this is caused by the natural conditions (type of resources and crops, climate) and the structure of the energy system, and also by the specific political priorities linked to the agricultural and forestry sectors in those countries. Romania has a significant potential in organic waste, including waste generated in forestry sector, agro–food industry or municipal biodegradable wastes. Biomass is an emerging renewable fuel that can help to heat homes and buildings at lower impact to the environment and lower costs than fossil fuels. The fuel (usually in the form of biomass pellets) is made from sustainable materials, such as wood, which is easily replaced and in abundance, at a relatively cheap price. As people are becoming more and more conscious about their individual impact on the environment and looking into greener, more efficient alternatives, biomass is slowly becoming one of the nation’s favorite renewable heat technologies. Actually, sawdust as by–product from wood sawing process, doesn’t have much application because of its low burning efficient. However, by pressing the saw dust into pellets, it becomes a kind of high quality biofuel product – sawdust pellets or wood pellets.

Life Cycle Cost Analysis: An Evaluation of Renewable Heating Systems in Turkey

This paper presents a comparison of the LCC of five heating systems in four climate zones in Turkey. While being a country with huge renewable energy potential, Turkey's energy demand is met to a great extent by imported energy sources which constitute a substantial economic burden for Turkey. In this study, we analyzed the most common heating technologies, namely geothermal district heating systems (GDHS), natural gas-fired boilers, pellet-fired boilers, ground coupled heat pumps (GCHP) and coal-fired boiler technologies in terms of various criteria including life cycle cost (LCC), accessibility, initial investment cost, technical infrastructure, resource cost and annual heat cost. This study is vital to determine the shortcomings and strengths of the renewable heating (REH) technologies, both economically and technologically against non-REH technologies. The outcomes of the study may eventually assist home owners, property developers and policy makers in taking informed decisions in case of new construction or renovation, or proposing new policy mechanisms to promote the REH technologies. This study revealed that, due to the high labor intensity, inadequate supply chain of energy sources and structural constrains; REH technologies are not cost competitive against non-REH technologies in Turkey. Turkey is expected to revisit its medium-term energy policy to ensure wide application of REH technologies, introduce encouraging support mechanisms, and prioritize REH technologies on the basis of Turkey's resource mix and policy goals. If appropriate policies are in place and obstacles are eliminated, the potential of renewable energy can be exploited and market expansion of REH technologies can be realized.

Will domestic consumers take up the renewable heat incentive? An analysis of the barriers to heat pump adoption using agent-based modelling

The UK Government introduced the tariff-based domestic Renewable Heat Incentive (RHI) in April 2014 to encourage installation of renewable heat technologies as a key component of its carbon reduction policy. Of these, heat pumps are considered to be the most promising for widespread adoption and as such are the subject of this paper. Pilot studies prior to introduction of the policy identified non-financial barriers to uptake, such as the “hassle factor” involved, and initial figures indeed indicate that uptake is lower than expected. We analyse these non-financial barriers using an agent-based model and conclude that there is a tipping point beyond which adoption is likely to fall very sharply. We suggest that the RHI’s complex and stringent compliance requirements for home inspections and heat emitter performance may well have driven adoption past this point and that further intervention may be required if the key aims of the RHI are to be achieved.

Anchoring energy efficiency information in households’ everyday projects: peoples’ understanding of renewable heating systems

This article claims that the contents of energy conservation information policy instruments must be better adapted to household members’ everyday life experiences in order to capture their interest and transform information into action. The article elaborates on how to ground energy policy information in the everyday doings and strivings of households. Using two time-geographical concepts, i.e. activity and project, we investigate how people understand and define their energy-related activities as parts of overarching everyday projects with a focus on the constraints on energy conservation. The analysis is empirically based on interview data from a case study of households’ use of renewable heating technologies. The results illustrate how peoples’ heating activities are related to everyday projects such as reducing environmental impact, comfort for a convenient daily life, the household budget balance, learning about and/or maintaining home technologies and hobbies. One conclusion is that information instruments focusing solely on one or two such projects might hamper the translation from information to action and also limit the number of people interested in or able to access the information. Another conclusion is that the growing use of energy-efficient technologies might influence new habits and perceptions of the everyday use of energy, making common economic motives for saving energy less useful. Anchoring energy-related information and support in the everyday activities and projects of households would facilitate the translation process. If this is achieved, information could prove a useful instrument in the broader reorganization of societal institutions in a sustainable direction.

Greenhouse gas emissions from renewable energy sources: A review of lifecycle considerations

Abstract Electricity and heat generation are key contributors to global emissions of greenhouse gases (GHG). In this paper, specific attention is paid to renewable energy technologies (RETs) for electricity and heat generation and reviews current understanding and estimates of life cycle GHG emissions from a range of renewable electricity and heat generation technologies. Comprehensive literature reviews for each RET were carried out. The 79 studies reviewed involved the life cycle assessment (LCA) of renewable electricity and heat generation based on onshore and offshore winds, hydropower, marine technologies (wave power and tidal energy), geothermal, photovoltaic (PV), solar thermal, biomass, waste, and heat pumps. The study demonstrates the variability of existing LCA studies (results) in tracking GHG emissions for electricity and heat generation from RETs. This review has shown that the lowest GHG emissions were associated with offshore wind technologies (mean life cycle GHG emissions could be 5.3–13 g CO2 eq/kWh). Results compared with GHG estimates by fossil fuel heat and electricity indicated that life cycle GHG emissions are comparatively higher in conventional sources as compared to renewable sources with the exception of nuclear-based power electricity generation. In this present study, considering renewable energy sources, waste treatment and dedicated biomass technologies (DBTs) were found to potentially have high GHG emissions based on the feedstock, selected boundary and the inputs required for their production. The study identifies additional impacts associated with renewable electricity and heat technologies, points out the effectiveness of life cycle analysis (LCA) as a tool for assessing environmental impacts of renewable energy sources and concludes with opportunities for improvement in the future.