Suchergebnisse

I det nuværende danske energisystem bliver hoveddelen af den benyttede el og varme produceret på et kraftvarmeværk (KVV). Med stadig større produktion af el fra vedvarende energikilder bliver det en stadig større udfordring at tilpasse el og varmeproduktion til behovsprofilet, da produktions kapacitetens tekniske restriktioner begrænser den effektive produktion på KVV. Varmepumper (VP) kan benyttes til at afkoble sådanne begrænsninger, men den nuværende teknologi er ikke konkurrencedygtig. Metoder til at forbedre energi effektiviteten er nødvendige, for at kunne opnå de politisk fremlagte mål for CO2-emmisioner. Det præsenterede studie undersøger den mulige introduktion af VP fra både et termodynamisk- og system/operationsanalyse perspektiv, for at finde optimale integrations løsninger for både nutidige og fremtidige energisystemer. Fem generiske konfigurationer for VP i fjernvarme- (FV) systemer blev identificeret og sammenlignet ud fra en termodynamisk analyse. Den operative præstationsevne af konfigurationerne blev undersøgt både for den enkelte enhed og fra et system perspektiv for forskellige FV temperaturer, forskellige drivmidler og ved systemer med forskellige produktions teknologier i FV netværket. Analysen viste at tre konfigurationer er særligt fordelagtige, hvorimod de to tilbageværende konfigurationer, set fra et system perspektiv, præsterer tilsvarende eller endog dårligere end det der kan forventes af en elektrisk vandvarmer. Den ene af de tre fordelagtige konfigurationer skal lokaliseres hos forbrugeren, hvorimod de to resterende kan placeres på lokaliteter med særligt gunstige temperaturer, hvor FV netværket benyttes til at distribuere varmen. En stor mængde operative og økonomiske restriktioner begrænser anvendelsen af VP som benytter naturlige arbejdsmedier, hvilket kan være de eneste mulige valg for Danske forhold. Begrænsningerne er meget afhængige af integrationen af energistrømmene for varme kilde og dræn. En vurdering af fordelagtige operative anlæg blev udført ud fra restriktioner som tilgængeligt køleteknisk udstyr og behovet for en positiv nutidsværdi for investeringen. Seks kompressions varme pumper (KVP) blev analyseret sideløbende med ammoniak-vand hybrid absorption kompressions varme pumpe (HAKVP), hvilket korresponderer til en øvre begrænsning i dræn temperature op til 150 °C. Den bedste disponible teknologi blev bestemt for hver mulig kombination af kilde og dræn temperaturer. Resultaterne viste at fem forskellige VP systemer fremsætter den bedste tilgængelige teknologi ved forskellige dele af det samlede arbejdsområde. Ammoniak-vand HAKVP og ammoniak KVP systemer med enten lav eller højtrykskomponenter er fordelagtige for en meget stor del af de analyserede dræn temperaturer og temperaturløft. Krav til dræn temperaturer og temperaturløft kan ikke tilfredsstilles for mange FV systemer hvis VP varmer til fremløbstemperaturen, med de benyttede økonomiske begrænsninger inkluderet i analysen. Den specifikke ydeevne for to FV VP konfigurationer blev undersøgt i yderligere detalje, hvortil der benyttes endelige temperatur niveauer som svarer til en række typiske FV netværk. Otte systemer blev analyseret for deres anvendelighed, og systemerne blev optimeret til hvert driftspunkt ved brug af exergoøkonomisk analyse. De enkelte VP blev sammenlignet baseret på prisen af den producerede varme. Resultaterne viser, at de tekniske begrænsninger medfører en betydeligt forøget pris på varme ved høje FV temperaturer, sammenlignet med den mest konkurrencedygtige termodynamiske kredsproces. Ved høje og mellemhøje temperaturløft er det muligt at opnå en kredsproces effektivitet på op til 45-50 % af det teoretisk mulige (i forhold til Lorenz processen), hvorimod så lave virkningsgrader som 36 % må forventes for lave temperaturløft. Tre typisk anvendte operations analyse metoder blev analyseret for deres påvirkning på driftsstyring for energiteknologier. Ved at fokusere på den fysiske repræsentation af KVV, synes det klart at den simple repræsentation tillader ugennemførlig produktion. Når blandet heltals programmering (BHP) og ikke lineær programmering (ILP) benyttes, bliver antallet af driftstimer og produktionen af varme fra VP betydeligt forøget, da VP kan benyttes til at udligne driftsprofilet for KVV i energisystemer med betydelige tekniske begrænsninger. En BHP energi system model blev udviklet, med fokus på detaljeret repræsentation af KVV og VP. To energiscenarier blev benyttet til analysen, et nuværende, som er valideret for året 2011, og et fremtidigt scenarie, som modsvarer det energiplanlæggere foreslår for 2025, hvor reduktioner af CO2-emissioner er en særlig indsats. Den ændrede drift for elektricitets produktions enheder fører til genovervejelse af optimum for FV netværks temperaturer, for at opnå den laveste pris og de laveste CO2-emissioner. Den udviklede energisystem model blev benyttet til at analysere den ændrede produktion. Produktions ændringer fra typiske KVV teknologier blev benyttet til at repræsentere den ændrede produktion af el og varme for ændrede FV temperaturer. Resultaterne viser at forbruget af primær energi og systemets omkostninger kan reduceres med ca. 5-7 % ved FV fremløbstemperaturer på 60 til 70 °C for 2025 scenariet. Yderligere reduktion i FV temperaturer resulterer i modsat rettede tendenser, da varmt brugsvand skal benytte stadig større mængder el for at opnå de nødvendige temperaturer. Resultaterne er netværks specifikke, da de repræsenterer specifikke FV forsyningsværker og netværk restriktioner, men tilsvarende tendenser kan forventes for andre store FV netværker. ; In the current Danish energy system, the majority of electricity and heat is produced in combined heat and power (CHP) plants. With increasing shares of intermittent renewable power production, it becomes a challenging task to match power and heat production to its demand curves, as production capacity constraints limit the efficient operation of the CHP plants. Heat pumps (HPs) can be used to decouple such constraints, but current state of the art are not competitive all things considered. Methods to improve the high energy efficiency are required to match the politically agreed carbon emission goals. The presented study investigates the possible introduction of HPs from both a thermodynamic and a system/operation management perspective, in order to find optimal integration schemes in both current and future energy scenarios. Five generic configurations of HPs in district heating (DH) systems were identified and compared based on a thermodynamic analysis. The operational performance of the configurations were investigated at both local and system level considering different DH network temperatures, different fuels and different production technologies in the DH network. The analysis show that three configurations are particular advantageous, whereas the two remaining configurations result in system performance close to or below what may be expected from an electric heater. One of the three advantageous configurations is required to be positioned at the location of the heat demand, whereas the two remaining can be located at positions with availability of high temperature sources by utilising the DH network to distribute the heat. A large amount of operational and economic constraints limit the applicability of HPs operated with natural working fluids, which may be the only feasible choice in Danish conditions. The limitations are highly dependent on the integration of heat source and sink streams. An evaluation of feasible operating conditions was carried out considering the constraints of available refrigeration equipment and a requirement of a positive net present value of the investment. Six vapour compression heat pump (VCHP) systems were considered along with the ammonia-water hybrid absorption compression heat pump (HACHP), corresponding to an upper limit of the sink temperature of up to 150 °C. The best available technology was determined for each set of heat sink and source temperatures. The results showed that five different HP systems propose the best available technology at different parts of the complete domain. Ammonia-water HACHP and ammonia VCHP systems utilising either low or high pressure components are preferable very broad range of sink temperature and temperature lifts. With the considered economic constraints in place, the requirements in terms of sink temperatures and temperature lift are not met for many DH networks considering the configurations which heat to forward temperatures. The specific performance for two DH HP configurations were studied in detail, using the finite temperature levels of a range of common DH networks. Eight systems were examined in terms of applicability, and the systems were optimised for each operating condition using exergoeconomic theory. The HPs were compared based on cost of heat. The results show that including the practical applicability of components causes a significantly increased cost at high temperature lifts, compared to the most competitive thermodynamic cycle. At high and medium temperature lifts cycle efficiencies of 45 - 50 % of the theoretical maximum (Lorenz cycle limit) can be achieved, whereas for low temperature lifts, efficiencies as low as 36 % may be expected. Three frequently used operation optimisation methods were examined, in order to investigate their impact on operation management of energy system technologies. By focussing on the physical representation of a CHP-plant, it is clear that a simple representation allows infeasible production. Using MIP or NLP optimisation, the number of operation hours and the total production of heat from HPs are significantly increased, as the HPs may be used to shave the load patterns of CHP units in significantly constrained energy systems. A MIP energy system model was developed with focus on the detail level of features for representation of CHP and HP units. Two energy scenarios were considered, one current, which is a validated model for 2011, and a future scenario, as proposed by energy planners for 2025, where reductions in carbon emissions for heat is of major interest. The changed distribution of electricity generation technologies may suggest a reconsideration of optimum for DH network temperatures, in order to achieve low cost and minimum carbon emissions. The developed energy system model was used to investigate the changed operation. Production curves from typical CHP-plant technologies were used to represent the changed power and heat production for changed DH temperatures. The results show that both primary fuel consumption and cost can be reduced approximately 5-7 % at DH forward temperatures of 60 - 70 °C in 2025 scenario. Further reduction results in contrary tendencies as hot tap water requires increasing amounts of electricity to reach required temperatures. The results are network specific, as they represent the specific DH utility technologies and network constraints, but similar trends can be expected for other large DH networks.

The project Strategic Nordic Products – Heat pumps, includes an overview of legislation, national schemes and actions taken to promote energy efficient heat pumps, and makes recommendations on further actions and possible cooperation to be carried out by Nordic authorities. The project is part of Nordsyn under the Nordic Prime Ministers' overall green growth initiative: "The Nordic Region – leading in green growth" - read more at www.norden.org/greengrowth.

Denmark is striving towards 100% renewable energy system in 2050. Residential heat pumps are expected to be a part of that system.We propose two novel approaches to improve the representation of residential heat pumps: Coefficients of performance (COPs) are modelled as dependent on air and ground temperature while installation of ground-source heat pumps is constrained by available ground area. In this study, TIMES-DK model is utilised to test the effects of improved modelling of residential heat pumps on the Danish energy system until 2050.The analysis of the Danish energy system was done for politically agreed targets which include: at least 50% of electricity consumption from wind power starting from 2020, fossil fuel free heat and power sector from 2035 and 100% renewable energy system starting from 2050. Residential heat pumps supply around 25% of total residential heating demand after 2035. The improved modelling of residential heat pumps proved to have influence on the results. First, it would be optimal to invest in more ground-source heat pumps, but there is not enough available ground area. Second, the total system costs are higher when COPs are modelled as temperature-dependent compared to fixed COPs over a year.

In Confronting Climate Gridlock, environmental engineering professor Daniel Cohan argues that escaping the gravest perils of climate change will first require American diplomacy, technological innovation, and policy to catalyze decarbonization... READ MORE
The post Daniel Cohan on Heat Pumps, Policy, and Optimism appeared first on Yale University Press.

Heat pumps use the temperature difference between inside and outside areas to modify a refrigerant, either for heating or cooling. Doing so can lower the need for external heating energy for a household to some extent. The eventual impact depends on various factors, such as the external source for heating or cooling and the temperature difference. The use of heat pumps, and eventual benefits has not been studied in the context of subarctic areas, such as in Iceland. In Iceland, only remote areas do not have access to district heating from geothermal energy where households may, therefore, benefit from using heat pumps. It is the intent of this study to explore the observed benefits of using heat pumps in Iceland, both financially and energetically. This study further elaborates on incentives provided by the Icelandic government. Real data were gathered from the Icelandic energy authority for the analysis. It was found for the study database of 128 households that the annual electricity use was reduced from 37.8 to 26.7 kWh (an average 29.3% reduction) after installation of heat pumps. Large pumps (9.0–14.4 kW) and small pumps (5.0–9.0 kW) saved an average of 31.4 and 26.0% (95% confidence intervals), respectively. On average, households used approximately 26 MWh after installing a heat pump. When installing a small pump (5–9 kW), the mean annual saving (and 95% confidence intervals) was 10.6 (± 2.7) MWh (approximately 26%). However, when installing a larger pump, mean annual savings were 11.3 (± 1.6) MWh (Approximately 31%).

Part of: Thermally driven heat pumps for heating and cooling. – Ed.: Annett Kühn – Berlin: Universitätsverlag der TU Berlin, 2013 ISBN 978-3-7983-2686-6 (print) ISBN 978-3-7983-2596-8 (online) urn:nbn:de:kobv:83-opus4-39458 [http://nbn-resolving.de/urn:nbn:de:kobv:83-opus4-39458] ; Increased efforts to reduce CO2 emissions and continuous increases in fossil energy prices have led to stronger legislation concerning energy utilisation efficiency in the domestic heating sector. Accordingly, German gas utilities and the key European manufacturers of gas heating appliances have teamed up to form what is known as the "Gas Heat Pump Initiative" to introduce new heating technologies, which are capable of achieving an incremental improvement of gas utilisation efficiency compared to that delivered by gas condensing technology. This article provides a brief introduction to these innovative heating appliances and a presentation of the gas heat pump initiative.

Decarbonization of sugar factories for minimising the CO2-footprint has become a focus for sugar factories to survive in the contemporary world. Heat pumps can be a piece of the puzzle for meeting the challenge of elaborating the path to a green future. This paper explains the technological principles and shows some exemplary scenarios for integrating heat pumps into beet sugar factories. The scenarios demonstrate reductions between 2% and 30% of the total factory's CO2-emissions. The potentials are limited by the local electricity-gas-price-relationship, which defines a lower limit in regards to operating costs equality.

Currently, more than half of all Swedish single-family houses have an installed heat pump and more heat is supplied by heat pumps in Sweden than in any other nation. Despite the enormous impact of heat pumps on the Swedish energy system, the transition towards their use has gone relatively unnoticed. Hence the title of this thesis, 'A silent revolution'. This thesis provides an in-depth study of the Swedish transition towards heat pumps and how Swedish industries contributed to it. It approaches the topic from the perspective of value networks and 'coopetition', combined with the concept of complementarities. This approach has been inspired by the work of Verna Allee (2009) and Erik Dahmén (1991). In this thesis, value networks are networks of actors surrounding a specific business model, coopetition is used to describe the relationships between actors (as both competitive and cooperative), and the concept of complementarities is used to analyze the dynamics between synergistic elements and value networks in Sweden's heat pump sector and energy system. Based on this approach, the thesis explains how a durable web of relations and interdependencies between complementarities has developed within the heat pump sector and the energy system in Sweden, and between the two, during the country's transition to widespread use of heat pumps. Interest in heat pumps arose in Sweden and other parts of Europe during the 1970s. The Swedish energy system had been caught between international oil crises and national political mobilisation against nuclear power expansion. In this period of negative transformation pressure, the heat pump appeared as a promising alternative that could mitigate the use of oil and electricity for heating. In the 1970s, an early Swedish heat pump industry formed together with a growing heat pump market. A large number of diverse actors became involved in the Swedish heat pump sector, and the intense coopetition dynamics relating to heat pumps following the 1970s oil crisis contributed to durable ...

Increasing the use of heat pumps is an important measure for reducing carbon emissions in the heating sector as well as natural gas imports. This report uses an electricity sector model to investigate the effects of an accelerated expansion of the heat pump stock on the German electricity sector in 2030. Adding around six million heat pumps would increase electricity demand by nine percent in 2030; to meet this demand with solar energy, photovoltaic capacity would have to be expanded by 23 percent. Natural gas imports could be reduced by 15 percent. From a macroeconomic perspective, the higher the price of natural gas, the more advantageous it becomes to increase the use of heat pumps. Accelerating the transition to heat pumps, however, requires an ambitious and coordinated policy program that also focuses on the production capacity of heat pumps and on providing advanced training to workers - a kind of "Apollo program" for heat pumps.

The problem of making heating systems more efficient was imposed due to the trend of increasing the demand for energy correlated in the same time with the increase of energy costs. Out of the various forms of energy used, in the current trend of developing the technique, the heat energy has the largest share in the energy balance of a country. EU policy in this field, expressed by the White Paper and the European Directive 2001/77/EC on energy production from renewable sources, states that, by 2020, the European Union will need to provide the necessary energy in a ratio of about 15 % by harnessing renewable sources. A solution of recovering the important heat quantities from the environment is the use of heat pumps which offers a real alternative to classic fuels, while contributing to reducing CO2 emissions up to 50% compared to using conventional boilers. They get about three quarters of the energy required for heating from the environment, and for the rest, they use electricity as driving energy.

Heat pumps use the temperature difference between inside and outside areas to modify a refrigerant, either for heating or cooling. Doing so can lower the need for external heating energy for a household to some extent. The eventual impact depends on various factors, such as the external source for heating or cooling and the temperature difference. The use of heat pumps, and eventual benefits has not been studied in the context of subarctic areas, such as in Iceland. In Iceland, only remote areas do not have access to district heating from geothermal energy where households may, therefore, benefit from using heat pumps. It is the intent of this study to explore the observed benefits of using heat pumps in Iceland, both financially and energetically. This study further elaborates on incentives provided by the Icelandic government. Real data were gathered from the Icelandic energy authority for the analysis. It was found for the study database of 128 households that the annual electricity use was reduced from 37.8 to 26.7 kWh (an average 29.3% reduction) after installation of heat pumps. Large pumps (9.0–14.4 kW) and small pumps (5.0–9.0 kW) saved an average of 31.4 and 26.0% (95% confidence intervals), respectively. On average, households used approximately 26 MWh after installing a heat pump. When installing a small pump (5–9 kW), the mean annual saving (and 95% confidence intervals) was 10.6 ( ±± 2.7) MWh (approximately 26%). However, when installing a larger pump, mean annual savings were 11.3 ( ±± 1.6) MWh (Approximately 31%). ; Peer Reviewed