Abstract
Between 2009 and 2017 the share of wind and solar energy sources in the GB electricity generation mix increased from 2.5% to 17%. Due to the variable nature of these renewable sources, large thermal power stations designed for constant base-load operation have been required to operate more flexibly to compensate for fluctuations in renewable generation. This flexible operation results in increased thermal stress and reduced efficiency causing increased operation, maintenance and fuel costs for these assets. In this paper we present the results of what is, to the best of our knowledge, the first empirical study on the impact of renewables generation on startups, ramping and part-loading (collectively, ‘cycling’) of base-load generators. We develop regression models using half-hourly generation data from 2009 to 2017 that capture the impact of increased renewable penetration while taking into account confounding factors including seasonality and demand. We find that with 2009-levels of renewable generation, cycling in 2017 would have been less severe, with 20% fewer startups. We also present estimates for cycling under National Grid Future Energy Scenarios to 2030 with implications for investment in generation assets. Additionally, the dataset derived in this research is made available and comprises the first open-access dataset on cycling.
Highlights
Falling capital costs of renewable generation technologies, as well as greater acceptance of the threat of climate change, are leading to an increase in the penetration of variable renewable energy (VRE) in power systems globally [1]
In order to understand the relationship between cycling and VRE penetration at this resolution, we need to take into account these additional factors. This requires the development of models which we present in this paper that capture and quantify the impact of VRE on the power system
We estimate that the number of startups per week would have been 20% lower, load factor 10% higher and severe ramping events per week 6% lower in 2017 had VRE generation remained at 2009 levels
Summary
Falling capital costs of renewable generation technologies, as well as greater acceptance of the threat of climate change, are leading to an increase in the penetration of variable renewable energy (VRE) in power systems globally [1]. VRE operates at very low marginal cost, displacing conventional power stations in the generation mix when available. VRE cannot be controlled, and there is a requirement for the conventional generation mix to provide the flexibility required to compensate for the added uncertainty and variability, ensuring the balance of supply and demand [2]. There is a large body of energy systems modelling research investigating power systems under high levels of VRE penetration: for a thorough review, see [3]. There is a shortage of datadriven research into the impacts of VRE on power systems.
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