The Group of Experts on Gas of the United Nations Economic Commission for Europe (ECE) collaborated with the Group of Experts on Renewable Energy to identify and investigate potential synergies between natural gas and variable renewable energy (VRE) sources. These synergies have the potential to provide the requisite flexibility and affordability in order to include a growing proportion of variable renewable energy sources into the energy mix. Two distinct phases are outlined in this paper. As a facilitator of VRE integration, flexible, cost-competitive, and agile natural gas-fired generation is demonstrated in the first phase, which focuses on the near future. In the second stage of the project, which will take place over the medium and long terms, the scope of the renewable energy concept will be expanded to include not only renewable gas production but also renewable electricity production. The second phase is based on the concept of a hybrid energy system, which envisions the employment of new gases (renewable, decarbonized, and low carbon), in conjunction with the notion of sectoral integration, as drivers to promote VRE penetration and, as a result, reduce emissions of greenhouse gases. This book offers various recommendations to ECE member states about the development of consistent policy and regulatory frameworks for renewable energy across the ECE region. These frameworks include frameworks for renewable gases.