Continuous hydrogen production facilitates handling of climatic extreme events in a fully renewable Swedish power system

Hydrogen produced from renewable electricity can play an important role in deep decarbonisation of industry such as steel-production. Steady, full capacity hydrogen production can also be a source of negative balancing capacity to increase flexibility of fully renewable power systems. However, there is a trade-off between attaining economically favorable high-full load hours for the electrolyzer and the provision of system flexibility. To better understand this trade-off, we apply a dispatch model for the Swedish power system with long-term time series 29 years of electricity generation (hydro and wind) and demand at hourly temporal resolution, thus being able to represent climate extreme events.

In our hydrogen demand scenarios for Sweden we limit the hydrogen usage options to two pathways that are currently under development: for hydrotreatment of different bio-based feedstocks in biofuel production, and as use as reductant in fossil-free primary steel-making according to the HYBRIT (Hydrogen Breakthrough Ironmaking Technology) route. We applied three different scenarios that can be seen to represent either different ambition levels for decarbonization, or different time perspectives, and which result in different electrolysis loads on the system:

    • 850 MW electrolyzer capacity, corresponding to 5 TWh·a-1 hydrogen production for biofuels
    • 1700 MW electrolyzer capacity, corresponding to 10 TWh·a-1 hydrogen production for biofuels
    • 3500 MW electrolyzer capacity, corresponding to 10 TWh·a-1 hydrogen production for biofuels and 10.5 TWh·a-1 hydrogen for steel-making.

In comparison to the baseline scenario, more wind power is available in the system, as wind power is scaled accordingly to the average electrolyzer demand.

Results very well present the seasonal differences in demand and how hydro power and partly thermal power are used to balance seasonal differences i.e. extreme events are only observed in the winter months. Also, significant curtailment of wind power capacity is present at some points but less so in the winter months. Extreme events are considerably decreased when increasing electrolyzer capacity, as the electrolyzers are operated flexibly and therefore provide significant positive balancing energy to the system in times of low generation events. In particular, longer events are reduced, creating shorter events to some extent.
Even under the assumption of very low electrolyzer ramping capacities and no dispatch of thermal power for hydrogen production, electrolyzers operate at about 90% of full load and still provide sufficient flexibility to reduce the impact of climatic extreme events on the Swedish power system significantly.