Hydro reaches the PEAK

26 January 2011



The HydroPEAK project in Norway is researching the interaction between wind and water power. As well as evaluating the current role of renewable energy in the European system today, it is also looking towards the future


Climate study findings indicate that it will be necessary for industrial nations to reduce their greenhouse gas emissions by 80-95% by 2050 (IPCC 2007) – a goal that was officially endorsed by the Council of the European Union in October 2009. The European Union has established the target of achieving a 20% share of renewable energies in the overall energy mix by 2020. To reach this goal, 34% of Europe’s electricity needs must be met by renewable technologies, with wind power taking much of the increase.

In a recent study published by the European Commission (Caprose & al 2009) it is estimated that renewable electricity production in the 27 countries in EU will increase from 467TWh/yr in 2005 to 1343 Wh/yr in 2030. At the same time, the percentage of energy created from wind power will increase from 15% in 2005 to nearly 50% in 2030.

Hydropower is expected to grow slowly in the EU since most of the available sources have already been developed, with an increase from 307TWh in 2005 to 355TWh in 2030 (not including Norway which is not member of EU). In 2005 hydro contribution is 66% of all renewables, this percentage will gradually decrease to 26% in 2030, according to the Baseline 2009 Scenario. In total, this will bring renewable up to supply nearly one third of electricity demand in Europe in 2030.

In another study, the German Advisory Council on the Environment (SRU) investigated options for a reliable electricity supply in Germany, completely based on renewable energy sources by 2050. This report (SRU, 2010) shows that such a transition is possible, and that the main contribution of new renewable electricity production would have to come from wind power, mostly from offshore wind. But the report also points to the fact that a system with mainly wind power will be vulnerable due to large variability in wind power generation, and that some sort of backup is needed to supply balancing power during calm periods. Hydropower, and in particular Norwegian hydropower, is seen as the main contribution to load balancing, due to many large storage reservoirs and the possibility to develop new pumped storage capacity, utilising existing reservoirs. The energy storage capacity of Norwegian reservoirs amounts to ca 50% of the total in Europe.

Other, similar studies have been published and the trend seems clear. The expected increase in renewable electricity production in Northern Europe will mainly come from wind power, and in particular from offshore wind parks in the North Sea. The variability in wind will, however, also make it necessary to build a system of balancing power in order to maintain system stability. Today, hydropower seems to be the best option for producing such balancing power, in particular as pumped storage plants where water can be pumped into upper reservoirs during periods of surplus wind and returned during calm periods. The Norwegian hydropower system can give a very important contribution to the development of renewable energy in Europe, if new capacity is built and the grid is strengthened in and around the North Sea.

In the German study (SRU, 2010) up to 60,000 MW of new hydropower capacity was included in the scenarios. In other, ongoing studies in Norway 20-25,000MW of new capacity is seen as realistic. The new capacity will only be built in areas with existing hydropower projects and will not require the construction of new reservoirs.

The Norwegian hydropower system

Hydropower has been developed in Norway since 1885 when the first plant was commissioned. Today the total capacity is nearly 30,000MW and the average annual energy production is 120TWh, supplying almost 99% of all electricity consumption in Norway. The reservoirs can store 84TWh of energy, or nearly 70% of the average annual inflow. The total hydropower potential has been estimated to 205TWh, of this 120TWh is already developed, 45TWh is protected, leaving 40TWh for possible further development. Of this, ca. 50% is small hydro with no storage capacity (run-of-the-river type).

The present hydropower system in Norway has mainly been designed for supply of firm energy. The system also has some capacity for producing peaking power but there are also technical, legal and environmental limitations. With the planned introduction of large scale, non-regulated renewable energy (eg in offshore wind parks) it is expected that hydropower will have to provide much more balancing power and that new capacity has to be built.

Hydropower peaking, and hence rapid variations in flow and reservoir levels, means new challenges for the operation of the hydropower system, and may have adverse effects on machinery, hydraulic structures, dams and tunnels, and also in rivers and reservoirs. Increased demands on hydropower for load balancing in the Nordic and European power system can be met by changed operation of the existing system, upgrading and refurbishment and developing new hydropower plants with reservoirs and/or pumping capacity.

Background for the HydroPEAK project

The Norwegian government is strongly committed to developing more renewable energy and has recently given research on sustainable energy systems high priority, as a means to reduce greenhouse gas emissions and mitigate the effect of climate change. In 2008 the Parliament approved funding of eight new Research Centres on Environmentally Friendly Energy Systems, with a guaranteed basic funding for eight years. The centres were selected during a two-step screening process. At first 28 preliminary applications were screened, of these 17 were asked to submit a full application and finally eight of these were approved in February 2009. In this process, both Norwegian and international expert groups were used to review and prioritise among the many competing applications.

The eight centres that were finally approved and given funding were:

• Norwegian Centre for Offshore Wind Energy (NORCOWE).

• BIGCCS Centre – International CCS Research Centre.

• Subsurface CO2 storage – Critical Elements and Superior Strategy (SUCCESS).

• Norwegian Research Centre for Offshore Wind Technology (NOWITECH).

• Centre for Environmental Design of Renewable Energy (CEDREN).

• The Norwegian Research Centre for Solar Cell Technology.

• Bio-energy Innovation Centre (CENBIO).

• The Research Centre on Zero Emission Buildings (ZEB).

One of these centres, CEDREN, has the main focus on the environmental design of renewable energy, but also includes environmental design of power lines for transport of electricity. The main objective of CEDREN is to develop and communicate design solutions for renewable energy production that address environmental and societal challenges at local, regional, national and global levels.

The centre will refine and adapt the environmental impact analysis methodology originally developed and implemented for hydropower. These methods will be transferred to other forms of renewable energy production – initially to onshore wind power and power lines, and later to offshore wind power, bio-energy and solar energy. Although renewable energy from water, wind, sun and bio-resources will be critical in achieving Norway’s targeted greenhouse gas reductions, production may entail some negative local effects on the ecology and society, which may trigger public resistance and conflict. Gaining acceptance for the comprehensive expansion of renewable energy production will therefore require solutions that minimise negative social and ecological impact. At the same time, this expansion must be financially sound and feature technically stable systems. This will call for a coordinated and integrated effort involving many scientific disciplines.

Due to the strong interest in the development of wind power, particularly offshore wind power, the CEDREN project application was focusing on the need for a better interaction between wind and hydropower, including the study of environmental problems associated with the increasing use of hydropower for power balancing and peaking. One of the main projects in CEDREN is called HydroPEAK.

HydroPEAK

The full title of the project is “Hydro power development for peaking and load balancing in a European system with increasing use of non-regulated renewables”. The title points to the fact that the future hydropower system in Norway may be facing a new operational regime, compared to the traditional role, to supply firm power to industry and the consumer market in Norway. The demand for a much more variable operation, triggered by increasing amounts of wind power in the future, may lead to new technical, economic and environmental challenges to the hydropower system.

The objective of the HydroPEAK project is to study how the hydropower system can be used to support increasing amounts of non-regulated renewables and what type of adaptions that are needed both in the existing and future hydropower system. Some specific project aims are:

• To identify the changes in load characteristics in the hydro system in the new load scenario.

• To identify related technical and environmental problems in the hydropower system.

• To develop methods for mitigating or reducing negative effects.

• To develop improved methods for optimising operation of the hydropower system.

• To develop knowledge and methods for planning upgrading/refurbishment to meet the new demands on the hydropower system.

• To identify needs for new hydro in a new operational regime.

• To build capacity within selected areas (MSc and PhD students).

• To disseminate information and project results in Norway and internationally.

The HydroPEAK project consists of eight work packages, most of them include a PhD or PostDoc since the intention is not only to do useful research, but also to build up new research capacity and contribute to the recruitment of experts for the hydropower sector. There are six PhD students and one Post-Doc in the project, the first started already in 2009, while the last two will start up by the end of 2010.

HydroPEAK’s project leader is Professor Ånund Killingtveit ([email protected]). The project has a budget of 37 Mill NOK (US$6.2M) and it will be finished in 2014. It is financed by 50% from the Norwegian Research Council, 25% from the hydropower industry and 25% in kind contributions from the research institutions. A brief description of the main content in each WP is given below.

WP1: Scenarios and dissemination

The main purpose is to generate scenarios for future development of the renewable capacity in Europe and its impact on the hydropower system in Norway. Technical, economic and social premises for a ‘hydropeaking’ regime/market and important benefits and drawbacks will be discussed. The scenarios will be a framework for discussion and coordination in the project. A group of interested users and scientists will participate in the scenario formulations and later meet at regular intervals to contribute advice and recommendations during the project.

Project leader: Eivind Solvang ([email protected])

WP2: Hydrology

Anticipating increased demands from non-regulated energy production, the management of hydropower reservoirs for peaking or load balancing will require improved inflow prognosis tools for both long term management and short-term peaking operation, including flood management. Emphasis is set on improving these tools for short-term step simulation and improved model updating from observational data.

Project leader: Sjur Kolberg ([email protected])

WP3:The impact of short term effects on long term hydro scheduling

The increased variability of hydropower is not well represented in the long term scheduling models in use today. The limited representation of short term effects in these models may increasingly lead to incorrect water values and a non-optimal long term use of the reservoirs. Activities in this work package include: i) Taking into account the turbine related costs of rapid variations ii) A better representation of time delays, also for discharge and bypass constraints iii) The representation of new types of environmentally based and more dynamic constraints and iv) Reserve markets

Project leader: Gerard Doorman ([email protected] )

WP4: Pumped storage plants

Reversible pump turbines (RPT) are well suited for load governing and also for grid support regarding frequency and voltage governing. Increased amount of non-governing power will result in a major change in operation of the Norwegian RPT-plants. Today’s RPT plants are not able to meet the challenge of changing between pump- turbine and condenser mode fast enough to meet the demands on the grid. Topics to be investigated are i) Evaluate the demands for change in modes of operations ii) System dynamic evaluation of existing RPT-plants iii) Develop effective systems for altering between pumping and turbining.

Project Leader: Torbjørn Nielsen ([email protected] )

WP5: Frequency and load governing

A more varying power marked as well as a more dominating element of non-governing power, will challenge the existing governing and control systems. The governing stability is initially robust with good stability margins. Wind power will not contribute positive and result in reduced stability margins. The water power system will be exposed to more rapid and more frequent load changes which will result in pressure surges in penstocks and conduit system. Already there have been incidents causing higher loads on equipment and increased sand erosion. In quite a few occasions, mass oscillations have been the cause for emptying sand traps through the machinery.

Project Leader: Torbjørn Nielsen ([email protected] )

WP6: Effects of load fluctuation on tunnels and associated hydraulic structures

Transients may destabilise the tunnel roadway and scour deposits from sand traps, resulting in sand transport and turbine damage, and also destabilise entrapped air pockets resulting in blow outs. Pore pressure variations may destabilise the rock mass and trigger rock falls. Hydropower intakes and tunnels are generally poorly instrumented and monitored, and hence reliable data on loss of water, friction losses, air and sediment problems are virtually non-existent. In order to study the hydraulics of tunnel systems it is also necessary to develop reliable monitoring methods.

Project Leader: Leif Lia ([email protected] )

WP7: Physical effects of load fluctuations in rivers and reservoirs

Fluctuating water levels may destabilise banks along lakes and rivers and trigger slides. Frequent flood waves may increase scouring. In total this may lead to increased sediment and nutrient transport. Also, hydraulic structures like dams, weirs, bridges and revetments etc will be subjected to frequent fluctuations in hydraulic loadings which may have a destabilising effect. A general increase in the variability of river flow and more frequent floods due to climate change is likely to intensify these problems.

Project Leader: ([email protected] )

WP8: Ice problems in rivers

A more fluctuating production schedule could have adverse impacts on ice conditions, particularly if periods with low production permits an ice cover to form which is subsequently broken when releases are increased (mechanical ice-breakup). Also, predicted climate change towards a warmer winter climate is expected to create more frequent changes between ice forming periods and mild periods with increased river flow resulting in ice break up and ice-runs, especially in unregulated rivers. This could lead to more frequent ice runs which will have negative impacts both on the environment and on technical installations on the river, for example hydro intakes, bridges and revetments.

Project Leader: Knut Alfredsen ([email protected] )

User interaction and involvement

Both CEDREN and the HydroPEAK project have been planned in close cooperation with users, both within the hydropower industry, consultants and the energy and water management institutions in Norway. A number of national and international partners in Norway, the Nordic countries, Europe and North-America are participating actively or as advisors. User groups are set up in all projects to disseminate information and get user feedback at all levels. Most of the research involves fieldwork and lab work, and the increased funding of laboratory and field data collection equipment is an important contribution to improve research quality and to recruit MSc- and PhD-students.

Ånund Killingtveit is a Professor of Hydrology and Water Resources Engineering, Department of Hydraulic and Environmental Engineering, Norwegian University of Science and Technology. N-7491 Trondheim, Norway. Email: aanund.killingtvei


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