When prices are not enough: Procurement outcomes and non-price drivers in Brazil's electricity auctions (2005–2022)

Competitive electricity auctions are often expected to translate falling renewable costs into growing renewable procurement, particularly when they are designed as technology-neutral, price-based mechanisms. This paper describes how far that expectation holds in Brazil's Regulated Contracting Environment (Ambiente de Contratação Regulada, ACR), using the complete record of the National Electric Energy Agency (ANEEL) for 1455 new-generation projects contracted in 49 auction rounds between 2005 and 2022 (84.3 GW; R$ 264.3 billion in planned investment). The analysis is descriptive. It documents contracted capacity and certified firm energy (garantia física), capacity-weighted contract prices and outcomes disaggregated by auction modality, and relates them to Sustainable Development Goal 7 (SDG7). The renewable share was non-monotonic: 49% in 2005–2008, 97% in 2009–2013, 67% in 2014–2019 and 82% in 2021–2022 by contracted capacity, with the same pattern under firm-energy weighting (44%, 94%, 56% and 67%). Between their first auctions and 2022, wind and solar contract prices fell by 44% and 50% in real terms. Fossil capacity was contracted only in regular A-3/A-4 and A-5/A-6 energy auctions and in one legally mandated 2022 round; reserve-energy auctions contracted none. Across the 12 years with fossil contracting, the fossil-to-renewable price ratio and fossil volume show no negative association (Pearson r = +0.53; Spearman ρ = +0.17; r = +0.05 without 2008), whereas a purely price-driven reading would predict one. The evidence is consistent with outcomes being shaped by product definition, firm-energy rules, planning responses to hydrological stress and legal mandates, which operate alongside, and partly through, bid prices. Since 2021, reliability procurement has moved largely to dedicated capacity products, a shift with direct implications for aligning the ACR with SDG7.