Energy is highly but not clearly regulated in international law. The legal sources on which the governance of energy is based are plentiful but scattered around a vast legal expanse, which has so far been addressed through separate specialised accounts devoted to specific topics or branches. The purpose of this research seminar is two-fold: to provide an overall account of the international law of energy understood as the entirety of international law seen from the prism of energy; and to rely on this account to analyse the implications of the ongoing energy transformation for international law. We will begin by examining the foundations of the field (the internationalisation of energy transactions, energy as a legal object, the purposes of its regulations, the structure of international energy transactions, and the three main approaches to global energy governance). We will then study each approach. First, we will analyse the foundational approach, which relies on: rules conferring and allocating entitlements over energy; rules enabling and protecting energy transactions, mainly through trade, investment and transit regulation; rules regulating negative externalities, mainly through human rights and investment law. Secondly, we will focus on ad hoc legal approaches, such as joint development agreements (oil and gas), pipeline agreements, hydroelectricity agreements, offshore wind agreements, and electricity transmission agreements. Thirdly, we will study the centralised or proto-centralised approach, by reference to the international law of nuclear energy, producer and consumer organisations (e.g. OPEC and IEA), promotion organisations (e.g. IRENA) and regional organisations (in the EU, Latin American and the ASEAN area). Finally, the seminar will focus on the manifestations across the international law of energy of the ongoing energy transition from a carbon-intensive to a low-carbon economy. The seminar is intended for international law students, but it is also open to students of other disciplines specialising on energy and/or environmental governance. It will be based on Vinuales, The International Law of Energy (CUP, 2021), and a wide variety of specialised instruments and readings.