A major EU-funded energy innovation project to demonstrate how smart hydropower technologies can deliver a low-carbon, reliable and resilient power system has launched its first progress report.

The report, titled ‘Flexibility, technologies and scenarios for hydropower’, is by the Institute for Systems and Computer Engineering, Technology and Science (INESC TEC). INESC TEC is one of 19 organisations collaborating on the EU-funded XFLEX HYDRO initiative, which aims to show how more flexible hydro assets can help countries and regions to meet their renewable energy targets.

The €18m, four-year project is focused on seven demonstration sites across Portugal, France and Switzerland. It will conclude in 2023 with policy and market recommendations. Prof. Carlos Moreira, Senior Researcher at INESC TEC, explains the inspiration for the report and what it covers.

The pathway to decarbonisation in Europe will require a dramatic increase in variable renewable energy (VRE) production in the coming years. Based on the high renewables’ scenario of the European Commission’s Energy Roadmap 2050, which calls for a 97% share of renewable energy sources by 2050, a significant change in the European power generation mix is expected. The commitment to a low carbon future also comes with the progressive decommissioning of fossil-fuel generation, in addition to the plans of several European Union member states to close nuclear power plants.

From the system perspective, power system operators must constantly balance demand with supply to keep the grid secure and stable. However, with the growing levels of VRE – such as wind and solar sources – the complexity of this task increases tremendously across time scales ranging from real-time, through to hours and even days. The challenge will also increase as thermal power plants close, as it will reduce the capacity to provide regulating power to the grid to ensure the continuous load/generation balance. From a technical viewpoint, the main challenge for the future European power system consists in defining how it will be operated with a high share of VRE, and a reduced amount of flexible and dispatchable fossil-fuelled power plants. Several investigations are taking place worldwide, and these emphasise that it is of the upmost importance to develop power system flexibility and the associated ancillary services required.

Due to their already flexible capabilities, hydroelectric power plants (HPPs) will have a leading role in managing the growing need for flexibility in the system.  Hydropower, as a dispatchable, renewable energy source, can provide large quantities of both capacity (short-term power flexibility) and energy (medium-term and long-term power and energy flexibility) across different time scales. It therefore occupies a unique position as a flexible energy supplier. These advantages will become even more important as fossil-fuelled units are phased out. Further grid interconnections and other interventions, such as stationary batteries, electric vehicles and demand-response programmes, will also contribute solutions; however, flexible hydropower will increase in value as the proportion of VRE continues to grow.

Within this context, the overarching goal of the XFLEX HYDRO project is to demonstrate innovative solutions to maximise hydropower’s contribution to the flexibility of the grid.  XFLEX HYDRO’s technologies are being assessed in detail across seven demonstration sites in Portugal, France and Switzerland. These will enable a better understanding of the technical and economic benefits, as well as the challenges of each solution. The technological solutions being demonstrated are:

  • Digitalisation tools (Smart Power Plant Supervisor): using plant health monitoring and data capture to reduce maintenance needs and plant outage time; while also increasing efficiency and helping to minimise stresses on equipment under increased flexible operation. This will ultimately support hydro plant operators in their decision-making regarding the provision of flexibility services to the grid.
  • Integration of advanced control for a battery storage system: hybridising a battery storage system at a run-of-river hydro power plant, with the aim of providing extended flexibility and fast response services to the grid and increasing plant availability.
  • Integration of Pumping and Generating Power regulation using Hydraulic Short Circuit (HSC): through the tandem operation of the pumping and generating modes, HSC can enhance the power regulation services and operating ranges offered by pumped storage plants.
  • Integration of Doubly Fed Induction Machine (DFIM) variable-speed technology: aiming to extend operating range and add flexibility capabilities for the grid, while also improving annual efficiency and residual lifetime. Enhancing the power regulation range by running DFIM in HSC mode will also be assessed.
  • Integration of Full-Size Frequency Converter (FSFC) variable-speed technology: upgrading hydropower potential by integrating FSFC variable-speed technology, using its high flexibility capability and enhanced functionalities for plant operation.

A first step has been to develop a comprehensive framework to evaluate the technologies and improvements planned in the XFLEX HYDRO project, establishing a crucial baseline. This sets out the short-term flexibility and system support services (or ancillary services) required by the future power system, with a strong link to the hydro technologies being demonstrated. Market mechanisms (both current and expected) are also considered. This has been documented in an Ancillary Services Matrix, which maps the hydro technologies, flexible power services and emerging power markets in Europe. This will help inform different stakeholders of the technology options and provides a reporting framework for the project. The first stage of the Matrix presents the baseline case, i.e. the degree each hydropower facility currently meets or complies with the defined ancillary services. As the project progresses, the Matrix will be populated and updated to show the expected technological improvements with respect to the ancillary power services and corresponding markets.

Future scenarios of the power generation mix published by the European Network of Transmission System Operators (ENTSO-E), indicate that hydropower capacity (including pumped storage) could increase to approximately 280GW by 2040 under their National Trends scenario. This suggests an increase in the order of 50GW new-build capacity over the next two decades. Moreover, much of Europe’s existing hydro capacity was commissioned over 40 years ago. The data suggests that, unless recently modernised, over 125GW may need to be refurbished. With these figures in mind, the market potential for the flexibility technologies and methods being demonstrated in XFLEX HYDRO, at both new hydro plants as well as existing facilities, could be significant.

XFLEX HYDRO Key Performance Indicators: tracking progress of the project innovations

Research institute and university The Swiss Federal Institute of Technology Lausanne (EPFL), is leading related work to assess the impact of XFLEX HYDRO’s demonstrations on hydro plant operations and maintenance. Dr. Elena Vagnoni, scientist and lecturer at EPFL and XFLEX HYDRO Scientific Coordinator sets out the key parameters to be used.

To help evaluate XFLEX HYDRO’s technologies the Ancillary Services Matrix will show the gains of the HPPs in supporting the provision of ancillary services. As well as these essential services to support power system balancing, XFLEX HYDRO activities also aim to strengthen the plants flexibility in terms of dynamic response services, optimised maintenance and improved availability. For this, several key performance indicators (KPIs) have been defined to quantify the HPPs flexibility, focusing on the enhancement of operations and maintenance. This is being presented in a KPIs Matrix, which is currently under development. The KPIs Matrix will present the key parameters that will be evaluated to assess the benefits of each technological solution implemented in the demonstration projects. The identified KPIs are:

  • Digitalisation: the measures adopted in the HPP for e-monitoring, advanced control systems and predictive maintenance will be evaluated to assign a digitalisation index linked to improved performance.
  • Extended operating range (%): significant improvements in terms of operating range extension (off-design conditions) are foreseen.
  • Fast start and stop (s): the time of the transient operations is expected to be noticeably reduced.
  • Fast turbine turbine-pump / pump-turbine transitions (s): the time of the transient operations from pump (-100% load) to turbine mode (100% load) and vice versa is expected to be noticeably reduced.
  • Fast ramp-up and ramp down (%/s): the rate for varying the power output in respect to the nominal condition is expected to rise.
  • Optimised maintenance interval (h): the hours of operation between maintenance intervals are foreseen to increase, which will also denote a reduction of the outage time.
  • Loading factor (h/d): the average number of hours of operation in a day are computed to evaluate the improved usage of the HPP.
  • Extended availability (%): the percentage of availability of the HPP in a year, including planned maintenance, is estimated to highlight the increased readiness and availability of the HPP while decreasing unplanned maintenance, shortfall in the operations and unnecessary stops of the hydroelectric units.
  • Increased weighted efficiency (%): the global efficiency of the HPP will be estimated by considering not only the efficiency of the hydroelectric unit, but also the power consumption of the auxiliary equipment, duly weighted. It is expected the overall efficiency of the HPP will rise.

The KPIs will allow quantitative assessment of the HPPs improvements thanks to the XFLEX HYDRO innovation activities; as well as tracking of the implementation of the technologies during the demonstration phase of the project. Once completed, the KPIs Matrix is expected to highlight the potential of each technology demonstrated in the project, and their potential for integration across the hydropower fleet.

To download the report, and for more information about the project, visit www.xflexhydro.net

Acknowledgement: The Hydropower Extending Power System Flexibility (XFLEX HYDRO) project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 857832.