The Institute for Energy Transition and Sustainability (IETS) Pty Ltd, also trading as the ISETS Sustainability Institute, is an Australia-based virtual think tank and network-based research and consultancy organisation dedicated to advancing practical, inclusive, and evidence-based energy transitions. Operating through a committed and carefully selected expert network, IETS brings together researchers, policy experts, practitioners, and institutional partners from around the world to address key challenges in energy transition, climate change, and sustainable development. 

IETS conducts research, policy analysis, advisory services, and capacity-building activities for governments, international organisations, development partners, universities, and the private sector. Its work covers energy transition strategy, carbon markets, renewable energy, fossil-fuel transition, energy security, sustainable finance, critical minerals, just transition, clean technology adoption, and climate-compatible development.

IETS serves as the Secretariat for the International Society for Energy Transition Studies (ISETS), providing administrative, operational, communications, and programme coordination support. Through this role, IETS provides a professional platform for connecting researchers, policymakers, industry experts, and international organisations committed to sustainable energy transitions.