Approaches to account for imperfect foresight in assessing the contribution of Energy Storage Systems to resource adequacy (Joint Working Group C5/C1.043)

	Pippa Williams (Australia, C5)		Ben Vanderwal (Australia, C5)

 

Introduction and Background

 

As power systems transition to accommodate greater penetrations of variable renewable energy, short-duration energy storage, particularly Battery Energy Storage Systems (BESS), are being increasingly utilised to maintain supply-demand balance. For many power systems, particularly thermal-dominated systems, resource adequacy is assessed using dispatch models that assume perfect foresight – i.e., that variability in demand and renewable power is known in advance to inform intertemporal decision-making. Alternately, hydro-dominated systems typically use stochastic and/or heuristic models which consider uncertainty over days, seasons, and/or years. For short-duration storage such as BESS, an assumption of perfect foresight can overstate availability to contribute to resource adequacy, while traditional hydropower methodologies are less suited to cases where the storage duration is similar to the optimisation time-step.

 

Given BESS is projected to significantly contribute to dispatchable supply in future power systems, it is important to accurately assess the probability that both capacity and energy will be available when it is most needed.

 

Aim & Purpose of Working Group

 

The purpose of this working group is to understand and collate information about how different power systems and markets are considering energy storage in resource adequacy assessments. The work will consider implications from short-term (operational planning, hours or days ahead) to longer term (years-ahead, capacity expansion planning).

 

Scope

 

The Joint Working Group C5/C1.43 (JWG) will investigate regulatory practices and market design implementation in different countries to manage integration of short duration storage into operational resource adequacy assessment. This may relate to markets which do or do not have capacity mechanisms to reward suppliers to deliver reliable capacity when it is most required, during periods of system stress and low reserve conditions.

 

The JWG will mainly focus on:

 

• a survey of local and international market and utility practices and planning approaches;
• a literature survey of state of current thinking in this area.

 

An interim report at the end of completion of a and b. (e.g. webinar or Electra article) will be prepared at this point.

 

The information gathered will be assessed, and approaches will be compared in terms of trade-offs between:

 

• implementation complexity,
• computational complexity, and
• theoretical accuracy.

 

Comparison will also consider whether requirements and approaches differ according to factors such as market type (day-ahead vs real time) and dominant fuels in the existing system.

The work will assess, and if practicable develop, additional approaches for appropriately capturing the impact of imperfect foresight on short-duration storage in resource adequacy assessments.

The JWG will then develop a final report based on outcomes from the stages of work described above, to be delivered as a Technical Brochure, Electra article and webinar.

 

Conclusion

 

The JWG C5/C1.43 started in May 2025 and has been progressing since forming a working group collective in late August 2025. The JWG international survey has been circulated to national committees in February 2026, and additional survey responses are welcome. If you are interested to contribute please request a copy from your national C1 or C5 committee or directly from JWG secretary

 

As the topic is particularly complex the WG has been established as a joint working group with C1 and C5, and welcomes input from existing expertise throughout the global CIGRE community. We look forward to your interest and contribution to this topic and aim to provide an update on progress at the Paris 2026 Session.