Environmental Constraints in Hydropower Production

Environmental constraints protect the water systems that plants operate in. While these regulations are not directly linked to energy systems, they can greatly impact daily running of the plant, as well as power production flexibility.

Over the past years, our team has seen all manner of constraints. We have helped dozens of plants become fully compliant, accountable, and transparent. In this article, we review the main environmental constraints on hydropower production, and discuss how HYDROGRID Insight is improving flexibility while respecting these constraints.

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1. Downstream water release restrictions

Flow rate constraints

Flow rate requirements are imposed by the need to maintain optimal flows within a river system to allow for aquatic life to thrive or stop entire interconnected water systems from icing over. Often referred to as ‘environmental flow’, this requirement is most addressed through licensing agreements. These agreements specify minimum flow rates that must be always maintained, regardless of whether there are other competing uses for the water or economic factors.

HYDROGRID Insight generates predictive production plans obeying imposed turbine and gate constraints on downstream water flow. Our partners, such as Aventron (Boge II) or Hanneseth (Kvina), are required to maintain minimum generation at all times. Using HYDROGRID Insight, they configured minimum and maximum discharge limits, via our easy-to-use dashboard, setting their constraints. Flow output changes hourly according to the inflow and enables the enables the plants to operate within their complex discharge variation constraints.

Only once all environmental and regulatory requirements are met, HYDROGRID Insight will prioritise environmental flow through a turbine rather than a gate, for added production flexibility. For Clemenskraft (Norlandselva),mutliple constraints didn’t allow for that. The optimal solution for them was the use of an ecological flow gate, which was accounted for within Insight’s predictive planning.

Turbine ramping constraints

Once the minimum flow is ensured, turbine ramping effects on downstream infrastructure and habitats are considered. By imposing limits on the rates of discharge variation, energy production can be gradually ramped up and down. This limits sudden water level fluctuations and current formation.

Many hydropower asset managers, in our portfolio, encounter ramping constraints, and work with us on integrating these restrictions in day-ahead, mid and long-term planning. Examples include Clemenskraft (Nørlandselva) for whom fish populations require restricted ramping, or Fosenkraft (Teksdal) for whom the annual, recreational fishing season comes with extra water level management considerations. By accounting for these constraints, within its optimisation engine, HYDROGRID Insight maximises the use of flexibility and revenue.

Local fauna and human use constraints

Dams create artificial reservoirs that affect fish migration and habitats for other wildlife. Oftentimes, production planning also has to account for migrating patterns of local species and ensure their safe passage through the system, as well as the natural impact.

In other cases, water release restrictions may be imposed by downstream infrastructure risk, such as bridges or banks. The bridge downstream of Dalane’s (Haukland) Skarstemmevatn reservoir, for example, is protected from structural damage by a hard constraint which has been integrated in the plant’s production planning.

2. Reservoir level restrictions

Reservoir level constraints are also used to preserve habitats and facilitate recreational use. The amount of water that can be kept in a reservoir may be limited by certain regulations (or social factors) that can change throughout the course of a year.

Aventron (Boge ll) experiences challenging, regulatory, reservoir level fluctuations throughout the year. To increase plant flexibility, within these environmental constraints, careful year round water management was achieved with the help of HYDROGRID Insight. Once these level constraints were integrated within our tool, hydropower production optimization could then adapt to the limitations.

For a 5 MW plant in Finland, their cascade became a source of increased power production flexibility. Cascade optimization enables production assets in the same interconnected water system to coordinate towards achieving separate targets. By prioritizing price driven dispatch at the upstream power plant and using their downstream plant to regulate the water level in a predictive way, all concessions were respected, whilst increasing revenue.

3. Flood or drought control

Hydropower dams are used to control water levels in rivers and reservoirs, which can have important benefits for flood control or irrigation during droughts. Here is how HYDROGRID Insight advised our clients regarding drought risk in 2023, and flood risk in December 2022.

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Integrated constraint management for increased flexibility

Just like your power plant, our tool is not limited to environmental constraint management. We understand that any plant is simultaneously part of two interconnected, dynamic systems: a power system and a water system. It must always account for constraints, with limited operational resources. HYDROGRID Insight uses an integrated approach to predictive planning, bringing all variables under a single hood.

The past 20 years saw variable generation technologies, such as wind and solar photovoltaic (PV), become significant contributors to the power grid. In this context, hydropower remains the most efficient renewable energy storage option, and a sustainable aid to a stressed network. HYDROGRID Insight is designed to maximise this flexibility advantage in a changing power market and highlight its relevance for the future of clean energy.