Danish Energy System Research Articles

Prefeasibility study on optimal site location for Power‐to‐X: An experiment for the Danish energy system

Denmark has set ambitious goals to cut greenhouse gas emissions by 70 % by the year 2030, and in an effort to reach this, the Danish Energy Agency has proposed a Power-to-X strategy that involves an overall capacity target of 6 GW of electrolysis by 2030. The objective of the following study was to identify the optimal site location for siting an electrolyser for Power-to-X as a prefeasibility analysis. The results indicated that Jammerbugt was an ideal area, for an add on solution to an already existing wind turbine, with 1303 h of excess wind energy available for Power-to-X. A financial analysis showed that there was an NPV of - €126,032 after a 20-year period, which improves with a theoretical 20 % governmental subsidy to €16,662. Therefore, it was found that Power-to-X is still currently reliant on governmental support as a viable business case. The study's findings highlight the importance of this support for Power-to-X to be a viable business case, such as the decision to allocate 1.25 billion DKK for hydrogen production by 2030.

Impacts of flexible-cooling and waste-heat recovery from data centres on energy systems: A Danish case study

The fast development of large data centres increases energy demand, pressuring energy systems and potentially hindering progress towards climate targets. Nevertheless, data centres are also a potential sector-coupling interface supporting the energy transition through demand flexibility in electricity markets and waste-heat recovery for district heating systems. In this respect, this paper quantifies the economic and environmental benefits of integrating large data centres into highly renewable energy systems, using Denmark as a case study and focusing on the transition until 2035. The Balmorel energy system model optimises the investments and operation of the energy system along with the data centre's portfolio of flexible-cooling and waste-heat equipment. The results illustrate that waste-heat recovery displaces conventional heat pumps in district heating, indirectly reducing investments in photovoltaic capacity while increasing electricity exports. Integration reduces Danish energy system costs by 5.1% and carbon emissions by 1.4% throughout this period. More importantly, this study highlights the significance of optimal integration, which saves up to 63% of costs and 180% of emissions that non-integrated data centres would otherwise incur. While these figures depend on local conditions, they emphasise the high costs to society of non-integration and the need for appropriate policies to support such integration.

A Brief History of District Heating and Combined Heat and Power in Denmark: Promoting Energy Efficiency, Fuel Diversification, and Energy Flexibility

The World Energy Council ranks the Danish energy system among best in the world judging by the energy trilemma criteria: energy security, energy equity, and sustainability. District heating (DH) and CHPs are pivotal for this ranking. This brief historical account illustrates how a mix of historical events, collective societal experiences, cultural and political values inform the Danish history of DH and CHPs. After the global energy crisis in the 1970s, public and political sentiment called for energy independence, alternatives to imported fuels, and alternatives to nuclear power. National-scale collective heat infrastructure planning initiatives targeted the energy policy objectives: energy independence, fuel diversification, and energy efficiency, and a political culture of broad coalition agreements made the necessary long-term planning possible. In the following decades, growing environmental awareness and concern called for renewable energy resources as alternatives to fossil fuels. Research considered the role of collective memories and temporal distance (i.e., time) for this sociotechnical journey; it notes the innovative thinking, re-use/re-cycling and energy efficiency focus that still characterize the Danish DH communities today, and it suggests that the intangible, yet reliable nature of heat could lead to the rebound effect in end-user heat-consumption behaviours. The methodological question of how, and to what extent, historical insights and lessons learnt may be translated across contexts is raised and discussed. Although sociotechnical trajectories may have granted the Danish energy system a head-start in the global race towards low-carbon energy transitions, perhaps the route was less direct than popularly portrayed. The Danish DH sector currently faces challenges of growing biomass import dependency, but also the potentials of sector coupling and energy flexibility. Energy efficiency and energy flexibility potential may be harvested via DH and district cooling solutions in future ‘smart’ energy systems globally. Hopefully, insights and lessons learnt from this brief history of Danish DH and CHPs prove informative elsewhere.

The bidding strategies of large-scale battery storage in 100% renewable smart energy systems

Large-scale battery storage solutions have received wide interest as being one of the options to promote renewable energy (RE) penetration. The profitability of battery storages is affected by the bidding strategy adopted by the operator and is highly dependent on the operation of the rest of the energy system. Nevertheless, the coordination between the battery and the energy system has not been investigated in the literature yet. This paper provides a holistic hourly techno-economic analysis of the bidding strategies of large-scale Li-ion batteries in 100% renewable smart energy systems. As a case study, the 2050 Danish energy system is used to demonstrate the relationship between large-scale battery systems and the rest of the energy system. The results show that large-scale battery storage plays a limited role in future energy systems that follow the smart energy system concept. Likewise, the battery solution is only economically feasible in the Danish smart energy system at low battery storage capacities (few hours’ duration) with a low-profit margin rate (approx. 100%) and a short prognostic period (approx. 12 h) for operation planning. The finding of this study provides the general strategies of the battery bidding and operation in 100% RE systems.

Smart energy Denmark. A consistent and detailed strategy for a fully decarbonized society

This paper presents a strategy for achieving a fully decarbonized Danish energy system (including transport and industry) in 2045. The strategy could also be relevant for most countries at a global level. The energy system analysis includes hour-by-hour computer simulations leading to the design of a Smart Energy System with the ability to balance all sectors of the complete energy system. In the analysis, issues such as international shipping and aviation, the sustainable use of biomass, and the exchange of electricity and gas with neighbouring countries are all considered. Moreover, the energy system is coordinated with other sectors to achieve a fully decarbonized society. Finally, the size of the employment impact of investing in decarbonizing the Danish economy is discussed.

Blowing in the wind: A brief history of wind energy and wind power technologies in Denmark

This paper explores the history of wind power technologies and the integration of wind energy in the Danish energy system. It does so focusing particularly on historical events, socio-cultural and socio-political changes and priorities that were important on this technological journey. From the first primitive wind turbines in the late 1800s, to the world wars, through the energy- crisis in the 70s, and into the decades of growing environmental awareness and concern, this historical account describes how policy priorities in Denmark gradually translated from the focus on energy diversification, energy efficiency and energy independence to the focus on sustainability and renewable energy resources, with wind energy and wind power technologies at the top of the priority list. Historically, wind power has been - and it still is - popular in Denmark. However, as the modern wind power turbines gradually grew to industrial scale heights, unchallenged support for specific local wind farms could no longer be taken for granted. This paper also touches upon the frequently tacit dilemmas of renewable energy technology planning and deployment, for example issues of environmental justice, wind farm ownership structures, and the role of social psychology for low-carbon energy transition processes. Notably, attention is drawn to the representation biases that may result in the emphasis of wind farm opposition / grievances in the wider wind farm related debates, where resistance to local wind farm projects might derive from minority opposition groups. Insights and lessons learnt from this Danish history of wind power may prove valuable and inspirational for other countries engaging in low-carbon energy transitions.

Power-to-X in Denmark: An Analysis of Strengths, Weaknesses, Opportunities and Threats

Power-to-X is an upcoming sector-coupling technology that can play a role in the decarbonisation of energy systems. The aim of this study was to widen the current knowledge of strengths, weaknesses, opportunities, and threats (SWOT) of this innovative technology in the Danish context by utilizing the analytic hierarchy process (AHP) to evaluate and compare perception of academic and industrial experts. The results of this analysis indicate that the external factors such as current policy framework are more important than the internal technology related factors. Further, positive factors predominate negative ones, with academic experts indicating strengths as the most important category and practitioners’ opportunities. All experts consider the country being a P2X knowledge hub as one of the most important factors, and in the given context of the Danish energy system, wind developments and Danish industrial environment, seizing this opportunity could be the biggest enabler for P2X success.

The role of electrification and hydrogen in breaking the biomass bottleneck of the renewable energy system – A study on the Danish energy system

The aim of this study is to identify the technical solution space for future fully renewable energy systems that stays within a sustainable biomass demand. In the transition towards non-fossil energy and material systems, biomass is an attractive source of carbon for those demands that also in the non-fossil systems depend on high density, carbon containing fuels and feedstocks. However, extensive land use is already a sustainability challenge and an increase in future demands threat to exceed global sustainable biomass potentials which according to an international expert consensus is around 10 – 30 GJ/person/year in 2050. Our analytical review of 16 scenarios from 8 independent studies of fully renewable energy system designs, and synthesis of 9 generic system designs, reveals the significance of the role of electrification and hydrogen integration for building a fully renewable energy system which respects the global biomass limitations. The biomass demand of different fully renewable energy system designs was found to lie in the range of 0 GJ/person/year for highly integrated, electrified, pure electrofuel scenarios with up to 25 GJ/person/year of hydrogen to above 200 GJ/person/year for poorly integrated, full bioenergy scenarios with no electrification or hydrogen integration. It was found that a high degree of system electrification and hydrogen integration of at least 15 GJ/person/year is required to stay within sustainable biomass limits.

Modelling of renewable gas and renewable liquid fuels in future integrated energy systems

This study conducts an integrated energy system assessment to evaluate pathways for using locally distributed sustainable biomass resources in the conversion to renewable gas and liquid biofuels in future integrated energy systems. A modelling framework with a detailed spatiotemporal representation is used, optimising the usage and transportation of local biomass resources for producing renewable gas and renewable liquid fuels through the OptiFlow model, along with the comprehensive power and district heating model Balmorel, integrating short-term dynamics in the long-term planning horizon. Results for a fossil-independent Danish energy system by 2050 show that production of bio-jet fuel in Denmark would impose high pressure on national biomass resources. Electrofuels, such as biomethanol, have economic viability and promising potentials. The results regarding renewable gas production show that anaerobic co-digestion of a mixed feedstock to produce biogas, which is further upgraded to biomethane using water scrubbing for CO2 removal, would be the preferred option. Biorefineries are located near larger cities to benefit from economy of scale and access to large district heating networks, as excess heat from biorefineries could supply up to 21% of the national district heating demand. On the contrary, biogas plants would be located in the countryside, as the costs of transporting manure are a determining factor. Therefore, our study provides a novel modelling approach, which enables optimisation of geographical distributed resources for renewable gas and liquid fuel production, while taking synergies across energy vectors in account.

Analysis on Electrofuels in Future Energy Systems: A 2050 Case Study

A radical adjustment to current energy systems will be imperative in achieving the Paris Agreement. This paper analyses the holistic 2050 Danish energy system and particularly its future transport sector, which aims to be fossil fuel independent. Using a linear optimisation tool (Balmorel-OptiFlow), the role of electrofuels is analysed at a high temporal and geographic resolution for the Nordic + German region. Electrofuel technologies have been investigated and incorporated into the energy model creating a comprehensive catalogue of alternative fuel pathways. Results reveal an energy system with a high reliance on variable energy sources. Electrofuels that utilise biomass have been found to be more economically attractive compared to electrofuels using carbon capture. Biomass costs, fuel demands, and electricity prices drive the competition between the evaluated alternative fuel pathways. Carbon capture technologies are found to not play a role in the production of transport fuels unless future biomass resources are more limited or costly than expected. Additionally, it has been found that temporal resolution can greatly affect results when modelling alternative fuel pathways. The study concludes that electrofuels - particularly those using biomass - can play a prominent role in future transport sectors.

The role of data centres in the future Danish energy system

Data centres (DCs) are expected to satisfy the rising demand for internet services. Denmark alone is expected to host several large-scale DCs, whose demand for electricity in 2040 may reach 33% of 2017 national electricity consumption. Understanding the operation and interactions of DCs with energy systems is key to understanding their impacts on installed capacities, costs and emissions. The present paper makes three contributions in this regard. First, we introduce a thermodynamic model that relates the power consumption of DCs to their production of excess heat (EH). Second, the results are scaled up to represent DCs in a national energy-system model for the analysis of different scenarios. Third, scenarios are generated and analysed to quantify the impact of DCs on the Danish energy system until 2050. The results show that DCs might have significant impacts on Denmark’s power and district heating (DH) sectors. First, the power demand from DCs translates into an additional 3–6 GW of offshore wind capacity. Second, EH from DCs is beneficial to the whole energy system, the entire quantity of EH being utilized in four out of five scenarios. EH recovery from DCs is economically beneficial, providing from 4% to 27% of Denmark’s DH after 2040.

Cost comparison and optimization of gas electric hybrid heat pumps

AbstractThe residential heating sector can offer significant load‐shifting possibilities to the energy system. Currently 400,000 households in Denmark are heated by natural gas boilers. The power consumption corresponding to these boilers can offer high value to the stabilization of the wind intensive Danish energy system. Gas electric hybrid heat pumps (GEHHPs) are individual heat pumps consisting of an electric heat pump and a gas boiler. They enable a fully flexible operation of electric heat pumps by supplementing electricity with gas when necessary. In this paper, we construct a cost optimization model of a GEHHP and compare the levelized cost of heat of this system with other individual heating systems. We investigate the changes in the operation schedule of the GEHHP, both from a socio‐ and a private‐economic perspective, and analyze how certain economic and technological framework conditions influence their operation schedule. Our article shows that the end‐consumer's optimal operation schedule uses the gas boiler component of the GEHHP 24% of the time. Additionally, comparing the levelized cost of heat of the GEHHP with other heating alternatives proves that the GEHHP setup is the most cost efficient individual heating alternative.This article is categorized under: Energy Systems Analysis > Economics and Policy Energy Systems Economics > Economics and Policy Energy Systems Economics > Systems and Infrastructure

Exploring cost-effective transitions to fossil independent transportation in the future energy system of Denmark

In this paper, in the light of national targets of a fossil independent future Danish energy system, cost-effective deep decarbonisation solutions in transportation have been explored under base-, alternative technical-, and policy scenarios in the TIMES modelling environment. The TIMES-DK model was further developed to concurrently represent all emerging transport technologies (ETTs) in road- and off-road transport applications, disaggregated transport technologies and service demands segmentation to capture consumers preferences and heterogeneity, and to endogenise fuel infrastructures. The model runs optimise the societal surplus in between 2010 and 2050. There is a particular focus on the role of gas in transport. The results reveal that in between 2020 and 2040, natural gas (NG) could cost-efficiently serve as a transition fuel. Decarbonisation pace and fuel infrastructure assumptions were found to have a large impact on the NG adoption levels. This study showed that the combined use of liquid biofuels (mainly biomethanol), upgraded biogas, electricity, and hydrogen fuels would deliver cost-effective deep decarbonisation by 2050; however, their various decarbonisation roles vary within and across transport segments. Depending on the decarbonisation pace, a marginal CO2 abatement cost of 419–549 €/ton (or 1–1.29 €/L gasoline) is required by 2050 in Denmark. The results also showed that 25% and 30% cost reductions of BEVs and hydrogen fuel cell vehicles (HFCVs), compared to our central cost assumptions, would increase their respective adoption by 36% and 66% towards 2050. They show high market shares particularly in the medium size segment than in the small and large segments. Competition for limited biomass resources coupled with higher fuel demand results in adoption of ETTs.

Why curved wind turbine rows are better than straight ones

Wind turbine wake effects in wind farms not only reduce the wind farm power production but also influence the wind farm power dependency on wind direction. In this paper, the wake effects in wind farm layouts consisting of curved and straight wind turbine rows are studied using engineering wake models and a Reynolds-averaged Navier-Stokes model. These models predict a similar annual energy production for both wind farm layouts, but show stronger wake losses in the aligned wind directions for a rectangular wind farm layout, while the wake losses for a curved wind farm layout are more spread out over a larger wind direction sector. An energy system level simulation predicts that the enhanced spreading of wake losses over wind directions results in less hourly variability in energy generation on a Danish energy system level. Thus, our results show that a curved wind farm layout is more favorable compared to a wind farm layout with straight rows.

From Carbon Calculators to Energy System Analysis in Cities

Energy systems in cities need to be decarbonized and are becoming more integrated via energy sector coupling. Today, cities often use simple methods to assess their low carbon targets, e.g., carbon calculators, and these methods use annualized carbon reduction potentials. For example, reductions from heat savings in buildings or fuel demand in transport. This is done because it is simple and fast. This paper describes a methodology that goes beyond carbon calculators and assesses highly renewable energy systems. The methodology is carried out for a case city—Sønderborg, Denmark. Using a national 100% renewable energy study and a suitable energy system analysis tool (EnergyPLAN), the method accounts for inter-sector coupling and energy system dynamics. The energy system is assessed by comparing the results from the analysis tool against numerous key sustainability factors for a Smart Energy System. The paper illustrates how the method delivers a sustainable 100% renewable Smart Energy System for Sønderborg, which can be part of the Danish energy system in 2050 based on local resources. The paper discusses the broader applicability of the method within strategic energy planning.

Costs and benefits of preparing existing Danish buildings for low-temperature district heating

This paper aims to provide an overview of the costs and benefits of preparing existing space heating systems for low-temperature district heating. Necessary heating system improvements were assessed based on previous work carried out on the topic. This included evaluating the necessity of installing larger heating elements and improving heating system control. The costs of the identified heating system improvements were then estimated and compared with the savings achieved if district heating temperatures were lowered, from the perspective of both the total Danish energy system and the individual district heating customers. The investigations resulted in simple payback times of 1.2–4.3 years from an energy system perspective and 0.3–18.7 years for an individual district heating customer. The current study thus indicates that it is economically feasible to invest in an improved heating system control to enable a reduction in the district heating return temperatures.

TIMES-DK: Technology-rich multi-sectoral optimisation model of the Danish energy system

As Denmark progresses towards a carbon neutral future, energy system models are required to address the challenges of the energy transition. This article describes design, input data and current usage of TIMES-DK, the first Danish energy system model that includes the complete national energy system, covering long-term technology investments. The article aims at explaining the modelling approach; highlighting strengths and reflecting upon limitations of the model; illustrating possible applications of TIMES-DK and inspiring new model developments. Some of the key strengths of the model include simultaneous optimisation of operation and investments across the complete energy system over the whole modelling horizon, explicit representation of the most important sectors of the economy, modular structure and the possibility of linking to a computable general equilibrium model for an additional insight on, e.g. public finance or CO2-leakage. TIMES-DK is being developed in close collaboration between an energy agency, a university and a consulting firm, to improve its robustness, relevance and impact on policy making. It allows for a wide range of applications including exploratory energy scenarios and policy analysis. To meet challenges of the future, further development of the model is needed and consequently the article provides references to ongoing projects addressing current development needs, such as improved representation of transport and flexible handling of the temporal dimension. To support a democratic and transparent process around decisions for the future Danish energy system, TIMES-DK should become available to interested parties.

The role of district heating in coupling of the future renewable energy sectors

For the last decades energy efficiency initiatives have avoided enormous amounts of energy consumption, to the favor of the environment and consumer expenditures. Although there is still a big potential for further energy efficiency improvements it is time to move further and start preparing the whole energy system for the challenge of oversupply from intermittent renewable energy sources, particularly in the power sector. In 2015 the maximum one-hour power oversupply from wind turbines alone in Denmark happened the 26th of June, peaking at around 900 MW and the oversupply over a 15-hour period was 10 GWh. Known solutions to make use of oversupply in the power sector are power export, energy storage and halting the power generation. The power export needs to rely on sufficient capacity at local interconnectors, power demand in the importing country and there is an economic gain in the export. Energy storages can range from storing of power in batteries, pumped hydro, synthetic fuels to fuel displacing at other energy sectors. The last option is stopping the turbines, which should be avoided. The optimum energy storage would have large capacity, fast charging, high recovery efficiency and low cost. Scoring high on all criteria’s can be difficult when focusing on a single energy sector. By widening the perspective and start taking advantages of synergies between the energy sectors there is a possibility to score high on all three criteria’s. In this paper the potential of utilizing synergies between the power and heat sectors will be explored by considering the projections for the Danish energy system in 2025. The result of the analysis shows the optimum energy storage of renewable power is achieved through fuel displacement in the heating sector in combination with utility sized heat pumps, electric boilers and large thermal storages.

The electricity market in a renewable energy system

The transition to a 100% renewable energy system based on variable renewable energy raises technical but also institutional questions. The smart energy system concept integrates variable renewable energy by addressing the technical challenges through the integration of different energy sectors, but integration of variable renewable energy also entails a change in the cost structures, especially related to electricity. The effect of this change in cost structures on market prices is investigated. This is done through simulation of a 100% renewable energy system that utilises a large degree of cross-sector integration but maintaining the current electricity market structure. The paper uses a 100% renewable energy system scenario for a 2050 Danish energy system. This is reflected in the use of wind energy as the primary renewable energy source. It is concluded that the current electricity market structure is not able to financially sustain the amounts of wind power necessary for the transition to a 100% renewable energy system. Since earlier research shows that neither electricity production costs nor the total system costs is higher for the renewable path than the fossil-based alternatives, the conclusion in this paper points towards a need for reshaping the institutional structure of electricity trade.

The climate footprint of imports of combustible waste in systems with high shares of district heating and variable renewable energy

This work addressed the role of waste-to-energy (WtE) within the growing paradigm of the circular economy (CE), by combining long-term co-optimization of waste management and energy systems, to determine possible economic and climate impact consequences of future WtE capacity utilization. Co-optimization was realized by integration of a network optimization model for the waste sector, OptiFlow, with the partial equilibrium energy systems model Balmorel. The modelling framework allows to determine the effects of waste-derived energy production within energy systems, including induced and avoided energy (production and long-term investments). The article documents the application of this framework to an analysis of waste trade for WtE between European countries in the base year 2014 and prospectively until 2035, taking Denmark as example for an importing country. Results indicating present and long-term economic benefits for waste trade, under socio-economic conditions, were documented in a concurrent publication. Here, a broader consequential LCA approach was employed to appraise climate change impact potential in a variety of foreground and background conditions. We find that in 2014, trade of residual combustible waste was mostly beneficial from a climate perspective, as the Danish energy system still relies partly on fossil fuels. Towards 2035, climate advantages are uncertain and dependent on avoidance of higher impact waste management (i.e. sanitary landfilling), the differences in the energy carbon-intensity of importing and exporting countries, impact of global biomass supply, and the type and quantity of traded waste. In general, benefits from waste-derived energy production will be offset by direct combustion emissions as background systems decarbonize. Waste transport played only a minor role in the outcome. The study showcases integration of ESA in waste LCA to better account for affected (often referred as marginal) energy production.