Objective and Background
There is a global increase in the use of weather-sensitive renewable generation to meet carbon reduction targets, with technologies such as wind power and solar power playing a key role. The increasing weather sensitivity has started to bring attention to impacts of inter-annual variability on power systems, where it is sometimes still common for “typical meteorological years” to represent the weather-dependence within policy-driven analysis. This study investigates implications of increasing weather sensitivity on inter-annual power system variability, with a key aim of introducing the best possible meteorological data to the policy debate.
Multi-decadal time series of meteorological re-analysis data are combined with a simplistic representation of the Great Britain (GB) power system, of which the weather-dependent components are hourly electricity demand, hourly wind power production and hourly solar power production. Multiple power system scenarios are analysed, informed by National Grid’s Future Energy Scenarios (FES,2018). A Load duration curve (LDC) framework is used for analysis, from which policy relevant metrics for inter-annual system variability, peak load and daily storage requirements and are analysed.
At present the GB power system has winter heating-driven and lighting-driven peak demands, a modest solar resource and a more substantial contribution from onshore and offshore wind.
In a hypothetical GB power system with only wind generation, peak load reductions are found compared to systems with either no renewables, or only solar generation is present. Power systems with only solar generation provide more baseload plant disruption and an increased potential for curtailment than systems with only wind generation. Systems with only solar generation are however, significantly less inter-annually variable than those with only wind generation. A blend of wind and solar generation provide a reduction in potential curtailment to a solar-only system, and reduced inter-annual variability to a wind-only system.
The influences of inter-annual variability on power systems are largely influenced by the month in which a year is defined to start. If using a calendar year (where the meteorological winter is not consistent, i.e. Jan-Feb 1981 combined with December 1981, rather than December 1980) the influences of inter-annual variability larger than if a financial year (Apr-Apr) is used.
Using multi-decadal time series of weather-sensitive power components can provide insights into the potential impacts of inter-annual variability which cannot be seen when using shorter records. A blend of wind and solar power offers greater opportunity for non-renewables than an equal energy contribution from wind power alone. A sizeable solar contribution can also help mitigate the inter-annual variability of wind supply. The issues discussed become increasingly relevant when considering plausible renewable expansions at 2030.
FES (2018) Future Energy Scenarios, National Grid, UK, Tech. Rep. available at: http://fes.nationalgrid.com/