VGB POWERTECH 7 (2020) - International Journal for Generation and Storage of Electricity and Heat

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A journey through 100 years VGB | Hydropower | VGB POWERTECH · Issue 10 (2006) Hydro-power in Europe Hydro-power: Challenges in Europe Kurzfassung Wasserkraft: Herausforderungen in Europa Autoor Author Dipl.-Ing. Michel Vogien EDF, Mulhouse Cedex, France. Dipl.-Ing. Hans Peter Sistenich RWE Power AG, Essen, Germany. In der EU-25, wo andere regenerative Energien intensiv gefördert werden, kommen immer noch rund drei Viertel der regenerativen Erzeugung aus der Wasserkraft. Das VGB Steering Committee Hydro-power repräsentiert 20 Gesellschaften aus neun europäischen Ländern, die zusammen etwa 45.000 MW Wasserkraft betreiben. Auf Grundlage dieses breiten Wasserkraft-Know-hows beschreibt der vorliegende Beitrag die Herausforderungen der Wasserkraft in Europa. Zur Illustration werden Beispiele aus Frankreich, aber auch Österreich und Deutschland genutzt. Quelle der Herausforderungen sind zum einen die geänderten Marktbedingungen und zum anderen geänderte Umweltanforderungen. Kurz gesagt: Die Erzeugungskapazität der Wasserkraft muss erhalten und sogar ausgebaut werden, um den Anteil der Regenerativen im Energiemix zu erhalten. Auf diese Weise können die Ziele des Umweltschutzes (Begrenzung der CO 2 -Emissionen) und die Deckung des wachsenden Bedarfs in Einklang gebracht werden. Gleichzeitig haben sich die Rahmenbedingungen für den Betrieb und die Entwicklung der Wasserkraft unzweifelhaft geändert. Heute sind neue Antworten hinsichtlich des Naturschutzes erforderlich. Die erste Herausforderung ist es, die bestehenden Kraftwerke bei optimalen Kosten zu erhalten. Die Wasserkraftflotten bestehen aus eher alten Kraftwerken. Bei den Spitzenlastanlagen muss man neben dem natürlichen Alterungsprozess die wachsende Belastung der Anlagenkomponenten berücksichtigen. Außerdem können neue Auslegungserfordernisse aufwendige Anpassungen in bestehenden Kraftwerken verlangen. Der vorliegende Beitrag beschreibt die Konsequenzen dieser Faktoren: Beispiele für aufwendige Instandhaltungsmaßnahmen. Insgesamt erwarten die im Steering Committee Hydro-power vertretenen Gesellschaften in den nächsten zehn Jahren Reparaturbedarf an rund 17.000 MW mit einem Aufwand von etwa 1,4 Mrd. EUR. Wasserkraftbetreiber und -lieferanten müssen die Schlussfolgerungen hinsichtlich Kapazität und Flexibilität ziehen, um dieses umfangreiche Reparaturprogramm kosteneffizient und bei einem hohen Verfügbarkeitsniveau der Anlagen realisieren zu können. Die Entwicklung neuer Projekte ist die zweite Herausforderung. Im Vergleich zur weltweiten Situation ist das Wasserkraftpotenzial in Europa mit 75 % gut genutzt. Dennoch verbleibt ein nennenswertes bisher ungenutztes Potenzial in der Größenordnung von fast 200 TWh pro Jahr, welches zumindest teilweise erschlossen werden sollte. Neben dem Neubau von Anlagen bieten die Erweiterung bestehender Kraftwerke und die Installation von Restwasserturbinen interessante Möglichkeiten, sowohl die Ökologie als auch die Ökonomie zu verbessern. Insgesamt planen die Mitglieder des Steering Committee Hydro-power in den kommenden Jahren den Neubau von 2.000 MW neuer Leistung mit einem Investitionsvolumen von rd. 1,6 Mrd. EUR. Neben dem Neubau von Anlagen beschreibt ein Beispiel wird gezeigt, wie die bestehende Wasserkraftflotte optimiert werden kann. Ein weiteres Beispiel zeigt, dass die Jahrhunderte alte Technologie der Wasserkraftnutzung neue innovative Einsatzgebiete erschließen kann. Nicht zuletzt stellt die Integration neuer Umweltaspekte die dritte wesentliche Herausforderung dar. Die Ansprüche an die Berücksichtigung ökologischer Wünsche beim Betrieb und vor allem beim Neubau von Wasserkraftanlagen sind in den letzten Jahren gewachsen. Dabei geht es im Wesentlichen um drei Punkte: Erhöhung des Restwassers im alten Flussbett, Herstellen der Durchgängigkeit von Staustufen für Wasserlebewesen und die allgemeine Verbesserung der Gewässermorphologie. Die wesentlichen Treiber sind die Europäische Wasserrahmenrichtlinie (WRRL) und Verhandlungen zu Konzessionserneuerungen. Die Wasserkraftbetreiber stehen für einen integrierten Ansatz bei der Verbesserung der Gewässerökologie. Verbesserungen sollten zuerst dort vereinbart werden, wo eine signifikante ökologische Verbesserung mit dem geringsten Aufwand erreichbar ist. Bei den Entscheidungen sind komplexe Wirkungen zu berücksichtigen, wie das Beispiel der Erhöhung des Restwassers zeigt. Die neue Konzession für das Rheinkraftwerk Albbruck-Dogern an der deutsch-schweizerischen Grenze kann als Beispiel für eine ausgewogene Lösung von Ökologie und Ökonomie dienen. Hydro-power in the VGB Since 2003, the VGB has been offering the key hydro-power operators in Europe a platform for discussing specific issues of their generating segment. The VGB Steering Committee “Hydro-power” represents 20 companies from nine European countries that together operate some 45,000 MW of hydropower. The committee members are senior managers from the VGB member companies. It steers the work of the committee and of presently three project groups. The results of their work are used at international (e.g. IHA), European (e.g. Eurelectric) but also at national (national lobbying groups) levels. With that in mind, this article describes the challenges for hydro-power in Europe. For illustration purposes, it will use examples from France, but also from Austria and Germany. Hydro-power: The Most Important Renewable Energy with Potential Over 90 % of the world's renewably generated electricity stems from hydro-power. Also in EU-25, where other renewable energies enjoy massive subsidies, some 75 % of renewable generation still comes from hydro-power [1]. By its very nature, the share fluctuates between the individual European countries, whereby Germany, where wind displaced hydro-power as the most important source of renewable energy for the first time in 2005, is an exception. In comparison to the worldwide situation, the hydro-power potential in Europe is well utilised at a rate of 75 %. Nonetheless, there remains a significant, still unused, potential on a scale of almost 200 TWh, which should at least partly be exploited [2, 3] (Figure 1). Current Challenges Hydro-power is currently facing three main challenges: 1. Maintaining the existing facilities at optimum cost. 2. Developing new projects . 3. Integration of the new environmental aspects. On the one hand these challenges are the result of the new market situation and, on the other, of changed environmental requirements. Individually, the main drivers are: – With fully utilised generating capacities and unchanged and ambitious CO 2 emissions targets, the constantly growing demand for power cannot be satisfied without a growing contribution by hydro-power as the most significant renewable source of energy. – The growing share of those sources of energy that cannot be controlled based on consumption levels (mainly wind) requires additional balancing opportunities. This demands additional, highly flexible generation and larger storage capacities, but in the foreseeable future these can only be provided cost-effectively by hydropower plants. – The competitive market first leads to higher wear and tear in the storage and pumped storage power plants, as these are no longer operated to the technical criteria they were originally designed for, but VGB PowerTech 10/2006 29 76
A journey through 100 years VGB | Hydropower | VGB POWERTECH · Issue 10 (2006) Hydro-power in Europe Potential Development potential Developed potential 100 % 90 % 80 % 70 % 60 % 50 % 40 % 30 % 20 % 10 % 0 % 70 % must follow the market logic. At the same time, the additional expense for maintenance thus caused can no longer be pushed through directly onto the market. – The increased environmental awareness demands that a new equilibrium has to be found between the various uses of water. Where production of cost-effective CO 2 - free energy was at the forefront when the plants were built, the importance of other uses of the water, e.g. for leisure activities, has grown in recent decades. The following concrete examples illustrate the challenges and show interesting and in some cases new solutions. Maintaining the Existing Facilities at Optimum Cost 5500 TWh/a 1400 GW* Figure 1. Hydropower development potential. Built throughout the 20th century, particularly after the Second World War, hydro-electric generating fleets consist of rather old facilities. At EDF, for example, their average age is approximately 50 years. Since the facilities are designed to last and even to remain in place for centuries, they do not have a limited life span a priori in the same way as other industrial tools. However, they include equipment and structures of very different nature and with very different life spans like: – Collecting, storing and conveying water, – Transforming the gross hydraulic power into electrical power, – Automatic control and regulating measures. Managing the ageing of the facilities while taking varying account of these three functions represents an important challenge for hydraulic producers since this does not only concern the sustainability and availability of the facilities but also the safety of the hydraulic system and its competitiveness on the market. This management involves knowing 25 % 190 TWh/a 48 GW 20 % World Europe France 13.4 TWh/a 4 GW the mechanisms responsible for ageing and damage which, in hydraulics, reach levels of complexity that are extremely difficult to extrapolate from external experience in other fields of industry, since the equipment there is much more recent. In peak generation plants, in addition to natural ageing it is also necessary to take account of the wear on the equipment, which is being subjected to increasing levels of stress. Year after year, the records in terms of operating cycles are being broken: 104.348 in 2005 for approximately 80 telecontrolled plants of the EDF fleet compared to 79.177 in 1999, that is to say an increase of 31 %. The consequences of more use are apparent in the example of the hydraulic pumped starting converter at the German Wehr PSW. The growing number of pump starts led to a one third reduction in the service lives of the runner in these converters. The additional maintenance shutdowns thus required reduce the availability of the plant. The runners need to be replaced earlier than originally planned, and be manufactured in a higher-quality and more resistant material to improve the plant's availability again. [4]. In total, the companies represented in the Steering Committee “Hydro-power” expect repairs to be needed over the next ten years on some 17,000 MW with costs of around 1.4 billion [5]. This extensive repair programme must be realised cost-effectively to maintain the high availability level of the plants. That demands of us and our suppliers high flexibility and close co-operation in its implementation. After years of market-driven capacity adjustments, the need for well qualified repair capacity is growing. In individual fields this may also require that new providers be developed. The necessity of, and some interesting solutions for, such extensive maintenance measures are illustrated by the following examples of EDF hydro-power plants. Replacement of Penstock The Pragneres facility in the Pyrenees (195 MW; 320 GWh/a) is supplied by two penstocks: one located on the left bank of the Gave de Pau with a maximum flow of 13.5 m∆/s under a head of 925 m, the other located on the right bank with a maximum flow of 19 m∆/s under 1250 m. It is equipped with 3 units of the Pelton type (2 x 80 MW, 1 x 35 MW). The penstock on the right bank has a length of 1,950 m and a diameter of 1,600 mm. Built in 1952, it is of the self-hooped type: each section consists of a steel tube of small thickness, on which circular hoops of rectangular cross section are mounted, spaced apart at regular intervals. The actual hooping operation is carried out in the workshop, during pressurisation which makes it possible for the pipe to undergo plastic deformation and be placed definitively on the hoops with a controlled pre-stress. When the pressure is zero, the hoops are tight and the section is compressed. On several occasions, hoop failures have been detected. When a crack reaches a critical size, it degenerates into sudden failure of the hoop. The risk associated with these sudden hoop failures is the bursting of the sheet of the penstock, which is not dimensioned to withstand pressure on its own. In order to eliminate this risk, operation of the power station under the head of the right bank has been halted, and a decision has been taken to completely replace the section in question (the lower 785 m). This operation will take place between July 2006 and September 2008, and will cost around € 30 million in total. This example shows that degradation mechanisms associated with ageing are at work in an old system of penstocks. Given the risks in term of safety, and the difficulty in monitoring and managing the development of these phenomena on a day-to-day basis, partial or total replacement of certain penstocks may prove necessary. These replacement operations, which are liable to increase in the medium term, will make it necessary to preserve in Europe industrial sectors that are capable of carrying out large-scale operation using designer-type skills. In this matter, EDF has had some difficulty in mobilising the interest of the industrial sectors in question. Improving Hydraulic Safety by Recalibrating the Spillway The “flood” risk is one of the main risks to the safety of dams since any overflow due to insufficient conveyance of the flood prevention means may lead to failure of the facility. Therefore, the level of safety is improved by two different modes: 30 VGB PowerTech 10/2006 77
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