Can United Nations peace operations improve their effectiveness and strengthen longer-term positive legacies in host nations by shifting to greater use of renewable energy? Since the end of the Cold War and the growth of modern UN peace operations, attention has been focused on the missions’ mandate of supporting political strategies for peace and core objectives such as protecting civilians. Could missions better meet their mandate with improved energy options and reduced emissions, or is there a trade-off with the core objectives? As the missions are nearly fully dependent on diesel generators to power their operations, what is the UN’s responsibility to reduce emissions at a time when addressing climate change is a priority of the UN Secretary-General? Is there an ethical case to make for the UN to support greater use of renewable energy where it operates? And could the UN partner with host nations and others to support a shift in energy use that benefits the communities that host peace operations? This essay argues that missions could reduce their emissions and leverage their energy needs to increase security, strengthen ties to local communities, increase energy access, and support the climate goals of host nations. Drawing on case studies in recent peacekeeping missions and the author’s review of UN commitments across mandates, the Sustainable Development Goals, peacebuilding, and climate goals, this essay will address this area of potential innovation that can help build a positive legacy for UN missions and countries emerging from conflict.