Russell McKenna

Combining local preferences with multi-criteria decision analysis and linear optimization to develop feasible energy concepts in small communities

Abstract Decentralised community energy resources are often abundant in smaller, more rural communities. Such communities often lack the capacity to develop extensive energy concepts and thus to exploit these resources in a consistent way. This paper presents an integrated participatory approach to developing feasible energy concepts for small communities. The novelty lies in the combination of methods, the consideration of uncertainties, and the application to an exemplary municipality in Germany. Stakeholder workshops are combined with energy modelling and multi-criteria decision analysis (MCDA), and a high transferability is ensured with mainly public data. The workshop discussion revealed three values: economic sustainability, environmental sustainability, and local energy autonomy. A total of eight alternatives for the 2030 energy system are identified to achieve these values. We find that an alternative that seeks only maximization of economic sustainability should be rejected based on elicited preferences. Instead, several alternatives seeking a maximization of environmental sustainability with constraints on economic sustainability (i.e. total cost) and local energy autonomy consistently achieve the highest overall performance scores. A maximization of economic sustainability or local energy autonomy alone results in the lowest overall performance scores and should therefore not be pursued by the community. The intermediate alternatives demonstrate that an equivalent performance gain with respect to autonomy comes at higher costs than the same gain with respect to environmental sustainability. Similarities between the best performing alternatives in terms of technologies that can be installed by 2030 show that our methodology can generate concrete and robust recommendations on building-level measures for energy system design.

The thermodynamic implications of electricity end-use for heat and power

Thermodynamic (energy and exergy) analysis can give rise to differing insights into the relative merits of the various end-uses of electricity for heat and power. The thermodynamic property known as ‘exergy’ reflects the ability to undertake ‘useful work’, but does not represent well heating processes within an energy sector. The end-use of electricity in the home, in the service sector, in industry, and the UK economy more generally has therefore been examined in order to estimate how much is used for heat and power, respectively. The share of electricity employed for heat and power applications has been studied, and alternative scenarios for the future development of the UK energy system were then used to evaluate the variation in heat/power share out to 2050. It was found that the proportion of electricity used to meet these end-use heat demands in the three sectors examined were likely to be quite high (∼50–60%), and that these shares are insensitive to the precise nature of the forward projections (forecasts, transition pathways or scenarios). The results represent a first indicative analysis of possible long-term trends in this heat/power share across the UK economy. Whilst the study is the first to consider this topic within such a timeframe, some of the necessary simplifying assumptions mean there are substantial uncertainties associated with the results. Where end-use heat demands are met by electricity, energy and exergy analysis should be performed in parallel in order to reflect the interrelated constraints imposed by the First and Second Laws of Thermodynamics. An understanding of the actual end-uses for electricity will also enable policy makers to take account of the implications of a greater end-use of electricity in the future.

Towards an improved nowcasting method by evaluating power profiles of PV systems to detect apparently atypical behavior

The installed capacity of PV plants has increased dramatically in the past years. A common approach to determine the actual power of an ensemble of PV systems within a specific region typically employs data from measured reference plants. Obviously the precision of the power estimation depends on having representative reference plants, which are not influenced by strong individual characteristics. The goal of this contribution is to detect such apparently atypical behavior of PV systems by comparing their measured power to simulations based on a nearby weather station and clear sky irradiance. Deviations are studied in the course of each day for the year 2012 and 48 PV systems, indicating systematic characteristics independent from meteorological conditions. Additionally, an approach is presented to detect such unexpected deviations automatically. This can be the basis for a dynamic nowcasting algorithm, which selects the reference units based on their (temporal) suitability.

A bottom-up method for feasible wind energy potential assessments, turbine and park placement

This work presents a bottom-up methodology based on graph-theoretical considerations to estimate the feasible potential as well as the economic costs of wind energy for the federal state of Baden-Württemberg in Germany on a wind farm level. Calculations are conducted based on high resolution land use data and wind speed data, using an algorithm to place wind farms by considering further constraints relating to land use planning. The feasible potential is found to be between 11.8 and 29.4 TWh, which is less than half than previous studies indicate for the technical potential since they neglect these constraints. Furthermore, a sensitivity analysis reveals a strong dependency on parameters of land use planning, as they are very land-consuming. As an important input factor for energy systems models these results may improve the quality of commercial and political decision-making.

Energieautarkie: Definitionen, Für- bzw. Gegenargumente, und entstehende Forschungsbedarfe

Ambitionierte europaische und nationale Zielvorgaben in der Energiepolitik fuhren in den letzten Jahren zu einem Umbruch der Energiewirtschaft, der vor allem durch den Ausbau von erneuerbaren Energien gepragt ist. Die Charakteristika dieser Energietrager bedingen, dass ihre Erschliesung wenigstens teilweise dezentral erfolgen muss. Der Ausbau der erneuerbaren Energien ist somit stark lokal und regional gepragt, wie z.B. in Deutschland durch die hohe Investition privater Personen in erneuerbare Energieanlagen und der Trend der Burgerenergie deutlich wird. Das Letztgenannte resultiert aus diversen soziookonomischen Motivationen wie dem Bedurfnis, eine aktive Rolle in der Energieversorgung zu ubernehmen und sich unabhangiger von zentralen Strukturen zu machen. Der Begriff der Energieautarkie hat sich in diesem Kontext etabliert und Forschungsfragen aufgeworfen, von denen dieser Beitrag einigen nachgeht. Die Ziele dieses Artikels sind, die sozialen und okonomischen Motive der Akteure sowie die technischen Fur- und Gegenargumente fur Energieautarkie zu identifizieren und zu hinterfragen. Dabei werden Definitionen und Bewertungsmethoden diskutiert und konkrete Forschungsbedarfe abgeleitet. Die Auswertung zeigt einen mangelnden Konsens in der Literatur auf, weswegen eine Arbeitsdefinition von Energieautarkie vorgeschlagen wird. Unter den sozialen Motivationen und Voraussetzungen fur Energieautarkie werden diverse Aspekte thematisiert und es zeigt sich, dass viele Konsumenten bereit sind, mehr fur lokale Energie zu bezahlen. Die techno-okonomischen Aspekte sind ausschlaggebend: der Grad der moglichen Energieautarkie ist durch die technischen Gegebenheiten bestimmt, insbesondere mussen ausreichende erneuerbare Energien-Potenziale vorhanden sein. Anderseits gibt es drei wesentliche technische Gegenargumente fur die Energieautarkie, namlich der Grosendegressionseffekt, der Glattungseffekt und die Versorgungssicherheit. Forschungsbedarfe werden in mehreren Bereichen identifiziert. Empirische Forschung zu der Frage der Ubertragbarkeit von Energieautarkie-Ansatzen und standardisierte Rahmenwerke sind notwendig, um die Vergleichbarkeit zwischen und Ubertragbarkeit von diversen Projekten zu ermoglichen. Vor allem bei der Erschliesung von nachfrageseitigen Potenzialen zur Lastverschiebung und Energieeffizienz scheinen die hier diskutierten Energieautarkieprojekte noch nicht so weit zu sein. Die Eignung und das Zusammenspiel zwischen unterschiedlichen Kommunen sowie die Frage nach dem optimalen Aggregationsgrad sind noch zu klaren. Schlieslich ergibt sich ein Forschungsbedarf fur Bewertungsmethoden und Indikatoren, um Energieautarkie auf der Ebene von einzelnen Kommunen und ihre Auswirkungen auf das ubergeordnete Energiesystem flachendeckend zu bewerten.

Energieeffizienz : Tagungsband des VDI-Expertenforums "Energieeffizienz in den Städten und der Industrie von morgen" ; vom 22. und 23. Februar 2011 am KIT, Karlsruhe

Das von der VDI-Gesellschaft Energie und Umwelt (VDI-GEU) und dem Karlsruher Institut fur Technologie (KIT) organisierte Expertenforum widmete sich der Diskussion um die Entwicklung und den Einsatz von Effizienztechnologien und -masnahmen in Stadten und der Industrie sowie deren technischer, okonomischer und okologischer Bewertung. Der vorliegende Tagungsband beleuchtet die anstehenden Herausforderungen und Chancen fur Industrie und Stadte, und beinhaltet diverse Beitrage rund um das Thema.