Global mining giant Rio Tinto has sold its 50 per cent stake in the Hydrogen Energy International Ltd (HEIL) joint venture in order to focus on a similar project in California. HEIL owns an interest in the Hydrogen Power Abu Dhabi (HPAD) project, which seeks to create cleaner electricity by storing gas emissions that would act as feedstock for a hydrogen power station. For the past two years, HEIL has been responsible for the development of the HPAD project. Rio and BP set up HEIL in 2007 to develop clean energy projects globally.