Ongoing deployment of renewable energy is driving a transformation of energy systems around the world.1 Spurred in part by rapid declines in the generation costs of solar photovoltaic (PV) and wind power, many countries have seen significant growth in installed capacity and generation from variable sources of renewable energy. In 2018, at least nine countries supplied more than 20% of their electricity generation from variable renewable energy (VRE)i.2 This transformation continues to be limited primarily to the electricity sector, however, as growth in the use of modern renewables in the heating, cooling and transport sectors remained minimal in 2018.3 ( See Global Overview chapter.)

Renewable energy can facilitate more efficient, sustainable and economical operation of suitably designed energy systems.4 However, varied technical, physical, organisational and legal barriers may slow or halt the growth of renewable energy.5 As shares of renewables grow in energy systems, additional challenges may emerge that require systems-focused approaches and strategies.6 Energy systems integration, as defined here, is the significant elimination of the impediments to higher penetration of renewable energy (in particular VRE) in energy systems – including in power grids, heating and cooling systems, and transport fuelling systemsii.

This integration is advanced through:

appropriate design of the operations, regulations and markets that govern energy systems;

infrastructural improvements or enhancements that aid access to renewables or facilitate their uptake; and

increased flexibility in energy demand and supply to accommodate VRE.

Energy systems integration is also advanced through technologies that promote the linking of energy supply and demand across electricity, thermal and transport applications. These so-called enabling technologies – such as energy storage, heat pumps and electric vehicles (EVs) – can expand or unlock markets for renewables by allowing renewable energy to supplement or replace fossil fuels, for example through the electrification of heating end-uses that traditionally are served by non-renewable resources.7 Some of these technologies are already commercially mature and widely deployed, while others are still emerging but experienced rapid growth in 2018.

This chapter focuses on efforts to integrate VRE into existing energy systems and to steer the evolution of power systems to better accommodate renewable energyiii. It also reviews the status of selected technologies that enable system integration of renewable energy in the heating, cooling and transport sectors.

iDefined more broadly, VRE also can include some forms of ocean power and hydropower. This chapter focuses primarily on solar PV and wind power, as these represent the fastest-growing VRE markets that are having the greatest impacts on energy systems. See Glossary for an extended definition of VRE.i

iiSee Chapter 6 of GSR 2018 for a more detailed overview of challenges related to renewable energy integration.ii

iiiThis chapter focuses on system planning and design but does not aim to provide a detailed overview of policy interventions for advancing renewables. See Policy Landscape chapter for an overview of developments in policies to integrate VRE in 2018.iii