arXiv subjects

Gorm B. Andresen

Publications and source records attributed to Gorm B. Andresen.

14 recordsLinked to original sources

arXiv2025

Lessons learned from establishing a rooftop photovoltaic system crowdsourced by students and employees at Aarhus University

Energy communities are promoted in the European legislation as a strategy to enable citizen participation in the energy transition. Solar photovoltaic (PV) systems, due to their distributed nature, present an opportunity to create such communities. At Aarhus University (Denmark), we have established an energy community consisting of a 98-kW rooftop solar PV installation, crowdsourced by students and employees of the university. The participants can buy one or several shares of the installation (which is divided into 900 shares), the electricity is consumed by the university, and the shareowners receive some economic compensation every year. The road to establishing this energy community has been rough, and we have gathered many lessons. In this manuscript, we present the 10 largest challenges which might arise when setting up a university energy community and our particular approach to facing them. Sharing these learnings might pave the way for those willing to establish their own energy community. We also include policy recommendations at the European, national, and municipal levels to facilitate the deployment of energy communities

physics.soc-ph↗

arXiv2022

30.000 ways to reach 55% decarbonization of the European electricity sector

Climate change mitigation is a global challenge that, however, needs to be resolved by national-level authorities, resembling a tragedy of the commons. This paradox is reflected at European scale, as climate commitments are made by the EU collectively, but implementation is the responsibility of individual Member States. Here, we investigate 30.000 near-optimal effort-sharing scenarios where the European electricity sector is decarbonized by at least 55% relative to 1990, in line with 2030 ambitions. Using a highly detailed brownfield electricity system optimization model, the optimal electricity system is simulated for a suite of effort-sharing scenarios. Results reveal large inequalities in the efforts required to decarbonize national electricity sectors, with some countries facing cost-optimal pathways to reach 55% emission reductions, while others are confronted with relatively high abatement costs. Specifically, we find that several countries with modest or low levels of GDP per capita will experience high abatement costs, and when passed over into electricity prices this may lead to increased energy poverty in certain parts of Europe

econ.GN↗

arXiv2021

Modeling all alternative solutions for highly renewable energy systems

As the world is transitioning towards highly renewable energy systems, advanced tools are needed to analyze such complex networks. Energy system design is, however, challenged by real-world objective functions consisting of a blurry mix of technical and socioeconomic agendas, with limitations that cannot always be clearly stated. As a result, it is highly likely that solutions which are techno-economically suboptimal will be preferable. Here, we present a method capable of determining the continuum containing all techno-economically near-optimal solutions, moving the field of energy system modeling from discrete solutions to a new era where continuous solution ranges are available. The presented method is applied to study a range of technical and socioeconomic metrics on a model of the European electricity system. The near-optimal region is found to be relatively flat allowing for solutions that are slightly more expensive than the optimum but better in terms of equality, land use, and implementation time.

cs.CE↗

arXiv2020

Early decarbonisation of the European energy system pays off

For a given carbon budget over several decades, different transformation rates for the energy system yield starkly different results. Here we consider a budget of 33 GtCO2 for the cumulative carbon dioxide emissions from the European electricity, heating, and transport sectors between 2020 and 2050, which represents Europe's contribution to the Paris Agreement. We have found that following an early and steady path in which emissions are strongly reduced in the first decade is more cost-effective than following a late and rapid path in which low initial reduction targets quickly deplete the carbon budget and require a sharp reduction later. We show that solar photovoltaic, onshore and offshore wind can become the cornerstone of a fully decarbonised energy system and that installation rates similar to historical maxima are required to achieve timely decarbonisation. Key to those results is a proper representation of existing balancing strategies through an open, hourly-resolved, networked model of the sector-coupled European energy system.

physics.soc-ph↗

arXiv2019

The role of photovoltaics in a sustainable European energy system under variable CO2 emissions targets, transmission capacities, and costs assumptions

PyPSA-Eur-Sec-30 is an open-source, hourly-resolved, networked model of the European energy system which includes one node per country as well as electricity, heating, and transport sectors. The capacity and dispatch of generation and storage technologies in every country can be cost-optimised under different CO2 emissions constraints. This paper presents an overview of the most relevant results previously obtained with the model, highlighting the influence of solar photovoltaic (PV) generation on them. For 95% CO2 emissions reduction, relative to 1990 level, PV generation supplies in average 33% of the electricity demand. Southern European countries install large PV capacities together with electric batteries, while northern countries install onshore and offshore wind capacities and use hydrogen storage and reinforced interconnections to deal with wind fluctuations. The strong daily generation profile of solar PV heavily impacts the dispatch time series of backup generation and storage technologies. The optimal PV and wind capacities are investigated for variable CO2 emissions, transmission interconnection among neighbouring countries, and cost assumptions.

physics.soc-ph↗

arXiv2019

The role of storage technologies throughout the decarbonisation of the sector-coupled European energy system

We use an open, hourly-resolved, networked model of the European energy system to investigate the storage requirements under decreasing CO$_2$ emissions targets and several sector-coupling scenarios. For the power system, significant storage capacities only emerge for CO$_2$ reductions higher than 80% of 1990 level in that sector. For 95% CO$_2$ reductions, the optimal system includes electric batteries and hydrogen storage energy capacities equivalent to 1.4 and 19.4 times the average hourly electricity demand. Coupling heating and transport sectors enables deeper global CO$_2$ reductions before the required storage capacities become significant, which highlights the importance of sector coupling strategies in the transition to low carbon energy systems. A binary selection of storage technologies is consistently found, i.e., electric batteries act as short-term storage to counterbalance solar photovoltaic generation while hydrogen storage smooths wind fluctuations. Flexibility from the electric vehicle batteries provided by coupling the transport sector avoid the need for additional stationary batteries and reduce the usage of pumped hydro storage. Coupling the heating sector brings to the system large capacities of thermal energy storage to compensate for the significant seasonal variation in heating demand.

physics.soc-ph↗

arXiv2018

Using validated reanalysis data to investigate the impact of the PV system configurations at high penetration levels in European countries

Long-term hourly time series representing the PV generation in European countries have been obtained and made available under open license. For every country, four different PV configurations, i.e. rooftop, optimum tilt, tracking, and delta have been investigated. These are shown to have a strong influence in the hourly difference between electricity demand and PV generation. To obtain PV time series, irradiance from CFSR reanalysis dataset is converted into electricity generation and aggregated at country level. Prior to conversion, reanalysis irradiance is bias corrected using satellite-based SARAH dataset and a globally-applicable methodology. Moreover, a novel procedure is proposed to infer the orientation and inclination angles representative for PV panels based on the historical PV output throughout the days around summer and winter solstices. A key strength of the methodology is that it doesn't rely on historical PV output data. Consequently, it can be applied in places with no existing knowledge of PV performance.

physics.soc-ph↗

arXiv2018

Cost sensitivity of optimal sector-coupled district heating production systems

Goals to reduce carbon emissions and changing electricity prices due to increasing penetrations of wind power generation affect the planning and operation of district heating production systems. Through extensive multivariate sensitivity analysis, this study estimates the robustness of future cost-optimal heat production systems under changing electricity prices, fuel cost and investment cost. Optimal production capacities are installed choosing from a range of well-established production and storage technologies including boilers, combined heat and power (CHP) units, power-to-heat technologies and heat storages. The optimal heat production system is characterized in three different electricity pricing scenarios: Historical, wind power dominated and demand dominated. Coal CHP, large heat pumps and heat storages dominate the optimal system if fossil fuels are allowed. Heat pumps and storages take over if fossil fuels are excluded. The capacity allocation between CHP and heat pumps is highly dependent on cost assumptions in the fossil fuel scenario, but the optimal capacities become much more robust if fossil fuels are not included. System cost becomes less robust in a fossil free scenario. If the electricity pricing is dominated by wind power generation or by the electricity demand, heat pumps become more favorable compared to cogeneration units. The need for heat storage more than doubles, if fossil fuels are not included, as the heating system becomes more closely coupled to the electricity system.

physics.soc-ph↗

arXiv2014

Renewable build-up pathways for the US: Generation costs are not system costs

The transition to a future electricity system based primarily on wind and solar PV is examined for all regions in the contiguous US. We present optimized pathways for the build-up of wind and solar power for least backup energy needs as well as for least cost obtained with a simplified, lightweight model based on long-term high resolution weather-determined generation data. In the absence of storage, the pathway which achieves the best match of generation and load, thus resulting in the least backup energy requirements, generally favors a combination of both technologies, with a wind/solar PV energy mix of about 80/20 in a fully renewable scenario. The least cost development is seen to start with 100% of the technology with the lowest average generation costs first, but with increasing renewable installations, economically unfavorable excess generation pushes it toward the minimal backup pathway. Surplus generation and the entailed costs can be reduced significantly by combining wind and solar power, and/or absorbing excess generation, for example with storage or transmission, or by coupling the electricity system to other energy sectors.

physics.soc-ph↗

arXiv2014

Features of a fully renewable US electricity system: Optimized mixes of wind and solar PV and transmission grid extensions

Wind and solar PV generation data for the entire contiguous US are calculated, on the basis of 32 years of weather data with temporal resolution of one hour and spatial resolution of 40x40km$^2$, assuming site-suitability-based as well as stochastic wind and solar PV capacity distributions throughout the country. These data are used to investigate a fully renewable electricity system, resting primarily upon wind and solar PV power. We find that the seasonal optimal mix of wind and solar PV comes at around 80% solar PV share, owing to the US summer load peak. By picking this mix, long-term storage requirements can be more than halved compared to a wind only mix. The daily optimal mix lies at about 80% wind share due to the nightly gap in solar PV production. Picking this mix instead of solar only reduces backup energy needs by about 50%. Furthermore, we calculate shifts in FERC (Federal Energy Regulatory Commission)-level LCOE (Levelized Costs Of Electricity) for wind and solar PV due to their differing resource quality and fluctuation patterns. LCOE vary by up to 35% due to regional conditions, and LCOE-optimal mixes turn out to largely follow resource quality. A transmission network enhancement among FERC regions is constructed to transfer high penetrations of solar and wind across FERC boundaries, based on a novel least-cost optimization approach.

physics.soc-ph↗

arXiv2014

What can transmission do for a fully renewable Europe?

Our research is centred around the question how to best integrate the variable renewable energy sources (VRES), wind power and solar photovoltaics, into the European electricity grid. The future electricity supply will be based to a large extend on these fluctuating resources. We have conducted a study, extrapolating national historical and targeted wind and solar power penetrations in Europe up to 100% VRES (R.A. Rodriguez et al, Renewable Energy 63, p. 467, Mar 2014 and S. Becker et al, Energy 64, p. 404, Jan 2014). A high share of VRES means large fluctuations in the generation, causing overproduction and deficits. One way to reduce such mismatches is power transmission spatially smoothing out the fluctuations. This has the potential to reduce the remaining shortages by sharing the surplus production of others. We find that shortages can at maximum be reduced by 40% in the hypothetical case of unlimited transmission capacities across all of Europe. A more realistic extension of the transmission grid, roughly quadrupling today's installation, turns out to be sufficient to harvest 90% of this potential benefit. Finally, the import and export of single countries is investigated. We conclude that a country's load size as well as its position in the network are the determining factors for its import/export opportunities.

physics.soc-ph↗

arXiv2013

Transmission grid extensions during the build-up of a fully renewable pan-European electricity supply

Spatio-temporal generation patterns for wind and solar photovoltaic power in Europe are used to investigate the future rise in transmission needs with an increasing penetration of these variable renewable energy sources (VRES) on the pan-European electricity system. VRES growth predictions according to the official National Renewable Energy Action Plans of the EU countries are used and extrapolated logistically up to a fully VRES-supplied power system. We find that keeping today's international net transfer capacities (NTCs) fixed over the next forty years reduces the final need for backup energy by 13% when compared to the situation with no NTCs. An overall doubling of today's NTCs will lead to a 26% reduction, and an overall quadrupling to a 33% reduction. The remaining need for backup energy is due to correlations in the generation patterns, and cannot be further reduced by transmission. The main investments in transmission lines are due during the ramp-up of VRES from 15% (as planned for 2020) to 80%. Additionally, our results show how the optimal mix between wind and solar energy shifts from about 70% to 80% wind share as the transmission grid is enhanced. Finally, we exemplify how reinforced transmission affects the import and export opportunities of single countries during the VRES ramp-up.

physics.soc-ph↗

arXiv2013

Transmission needs across a fully renewable European power system

The residual load and excess power generation of 27 European countries with a 100% penetration of variable renewable energy sources are explored in order to quantify the benefit of power transmission between countries. Estimates are based on extensive weather data, which allows for modelling of hourly mismatches between the demand and renewable generation from wind and solar photovoltaics. For separated countries, balancing is required to cover around 24% of the total annual energy consumption. This number can be reduced down to 15% once all countries are networked together with uncon- strained interconnectors. The reduction represents the maximum possible benefit of transmission for the countries. The total Net Transfer Capacity of the unconstrained interconnectors is roughly twelve times larger than current values. However, constrained interconnector capacities six times larger than the current values are found to provide 97% of the maximum possible benefit of cooperation. This motivates a detailed investigation of several constrained transmission capacity layouts to determine the export and import capabilities of countries participating in a fully renewable European electricity system.

math.OC↗

arXiv2010

Search For Trapped Antihydrogen

We present the results of an experiment to search for trapped antihydrogen atoms with the ALPHA antihydrogen trap at the CERN Antiproton Decelerator. Sensitive diagnostics of the temperatures, sizes, and densities of the trapped antiproton and positron plasmas have been developed, which in turn permitted development of techniques to precisely and reproducibly control the initial experimental parameters. The use of a position-sensitive annihilation vertex detector, together with the capability of controllably quenching the superconducting magnetic minimum trap, enabled us to carry out a high-sensitivity and low-background search for trapped synthesised antihydrogen atoms. We aim to identify the annihilations of antihydrogen atoms held for at least 130 ms in the trap before being released over ~30 ms. After a three-week experimental run in 2009 involving mixing of 10^7 antiprotons with 1.3 10^9 positrons to produce 6 10^5 antihydrogen atoms, we have identified six antiproton annihilation events that are consistent with the release of trapped antihydrogen. The cosmic ray background, estimated to contribute 0.14 counts, is incompatible with this observation at a significance of 5.6 sigma. Extensive simulations predict that an alternative source of annihilations, the escape of mirror-trapped antiprotons, is highly unlikely, though this possibility has not yet been ruled out experimentally.

physics.atom-ph↗