Hybridising hydro could ease grid constraints says Ember

A new report released by think tank Ember shows that adding wind and solar behind the meter of existing hydropower assets could not only lower network build-out costs but also bypass grid constraints altogether.

The report assesses hydropower assets in Austria, Bulgaria, France, Italy, Portugal, Romania and Spain, which combined account for 93GW of the EU’s 131GW hydropower.

Ember’s analysis shows that hydropower plants eligible for hybridisation operate at 19% of their maximum output on average.

Adding wind and solar could increase utilisation to 36% and 31%, respectively.

While sites vary, in some cases wind and solar could potentially triple use of the same grid connection.

More specifically, the report shows that 25GW of new wind and solar can be added behind the meter of existing hydropower plants without disrupting typical dispatch behaviour.

This means that 18% of upcoming renewable capacity could be integrated without requiring grid interventions or additional grid capacity, particularly important for countries experiencing grid constrains.

Grid constraints

The report comes as energy and price shocks, coupled with Europe’s drive for industrial competitiveness, highlight the need for electrification and increased renewable energy deployment.

However, grid constraints are already visible, with the report highlighting a shortfall of at least 120GW existing between available grid capacity and anticipated renewable growth by 2030.

While building out the grid is critical, hybridisation is seen as a more immediate solution that could offer relief. By utilising a mechanism called cable pooling, Ember explains that sites can operate as “partially integrated hybrids, with fixed export limits for each component, or as a single commercial entity with an overall export limit that optimises output.”

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The latter allows for the management of variable renewables and provides stability of supply.

Elisabeth Cremona, Energy Infrastructures Lead at Ember, comments: "Political ambitions mean nothing if clean electrons are stranded in connection queues. For countries facing gridlock, hybridisation offers an immediate, zero-intervention solution. 

"By stacking wind and solar behind existing grid connections, we can unlock the large-scale renewable deployment that underpins Europe’s security and competitiveness, while reducing the need for costly network expansions," concludes Cremona.

Legislative support

One of the findings of the report is that of the seven countries focused on, only Spain and Portugal have rules governing hybrid projects, indicating that regulatory frameworks across Europe remain underdeveloped and hybridisation overlooked.

Ember calls for the establishment of legislation to unblock and streamline hybrid projects while maximising existing infrastructure.

Ember further recommends that hybrid projects should benefit from simplified and accelerated grid connection procedures, given their minor network impacts and ability to unblock grid bottlenecks.

Finally, the report suggests that to maximise the use of existing grid connections, provisions that allow for overcapacity during hybridisation should be incorporated in national legislation.

Project potential

The report highlights hydro projects which are already demonstrating the potential of hybridisation.

Specifically, the Tâmega wind farm in Portugal will host a novel hybrid connection between hydroelectric and wind energy, sharing the same grid connection infrastructure at the Tâmega Electroproduction System substation.

According to Ember, floating solar is also emerging as a hybrid solution to be coupled with hydropower. It requires no additional land and reduces evaporation from hydro reservoirs.

The report highlights the Lazer floating solar power plant in France, which comprises over 50,000 solar panels and has a total installed capacity of 20MWp. Project owner EDF says the solar power plant complements the hydro power scheme, particularly in the summer months, by continuing to supply electricity when the water from the Lazer reservoir is used primarily for crop irrigation.