Gas4sure is a programmatic document setting out the role of natural gas in the transition to a sustainable energy supply. Being the cleanest fossil fuel, natural gas will play a relatively key part in this transition from a mainly fossil-based energy supply to one based on efficient technologies and renewable sources. Gas4sure is a follow-up to Green4sure, the green energy plan elaborated by CE Delft for the Dutch environmental and trades unions movements. Green4sure explains how in the next 25 years we can create an energy supply with half today’s79 CO2 emissions and what roles the various parties will need to play to make that future feasible. In Gas4sure the use of natural gas is not in itself the aim, but given the marked changes in conditions for the environmental impacts of the energy supply, rather an outline of the role of gas under those conditions.