The scope of environmental impact assessments (EIAs) has traditionally been limited to on-site effects. This approach faces limitations when dealing with intricate value chains. Particularly for projects involving biomass-to-energy facilities, the primary environmental impacts often originate from off-site biomass production. This article considers the resulting limitations of EIAs by using two legal disputes in France as illustrative examples. In the Gardanne and the La Mède cases, French Administrative Courts sought to establish the necessity for project proponents to incorporate supply-related impacts into the EIA process. Strategies aimed at broadening the scope of EIAs, either by expanding the assessed project boundaries or by invoking the concept of cumulative impacts, were not deemed the most relevant approaches. Instead, the concept of ‘indirect impact’ emerged as a valuable tool for incorporating supply-related impacts. However, to prevent the indirect impact concept from being disregarded as too ambiguous or ineffective, it should be complemented by precise criteria to determine whether an impact may be considered indirect. We study these avenues within the broader evolving landscape of EIA laws, and by exploring ways to harmonize EIAs with other regulatory instruments governing value chains.