Wind and solar have become established resources for low-carbon electricity around the world. Cost declines for those technologies now allow us a tantalizing vision of the not-too-distant future where our electricity is supplied almost exclusively by renewables. However, to make this vision a reality, our grids need to add resources that can compensate for the intermittency of these technologies.

Electricity systems have always been managed ‘flexibly’. Weather, work patterns, industry, or even sports schedules create predictable or unexpected drops or spikes in demand. Sudden system failures, such as power station or transmission outages, mean that backup generation has always been required to keep the lights on. Generally, suppliers have controlled generation from coal, gas or hydro plants to respond to whatever consumers demanded of the system.

Now that technology costs are competitive with fossil fuels, today’s challenge in the energy systems transition has shifted towards integration of dispatchable low-carbon electricity sources into the system – at the lowest possible cost.

With this challenge at the heart of its roadmap to accelerate a shift towards an affordable, reliable, sustainable and modern energy system, in 2016 the Energy Transitions Commission (ETC) commissioned Climate Policy Initiative (CPI) to examine four areas for its report:

1. What would be the maximum cost of an electricity system based entirely on renewable energy, including the cost of delivering flexibility, and how would that compare to fossil fuel- based options?
2. What technological and market-based options are available to provide this flexibility, how will costs develop, and which technology options should we prioritize for development?
3. How might flexibility needs and technology requirements vary as a function of regional differences?
4. What are the key policy and market design issues that need to be resolved?

CPI Energy Finance’s report, Flexibility: the path to low-carbon, low-cost electricity grids was commissioned by the ETC to support its report, Better Energy, Greater Prosperity, launched on 25 April 2017.