Feasibility and Requirements of a 100% Transition to Renewable Energy

Firm Power Generation 2023


The rigorous research reported in this study demonstrates that a 100% transition to renewable energy is feasible and cost effective with strategic, planned overbuilding of renewable capacity. Overbuilding solar, even a little, is found to dramatically reduce the amount (and hence cost) of the energy storage required to overcome the intermittency of renewables. The alternative is an order of magnitude more energy storage (probably Li+ batteries, given current trends) with some significant environmental and resource availability issues and more cost. The amount of overbuilding required depends on the cost of variable renewables relative to the cost of storage. Historically, the capital cost of renewables (particularly solar) has decreased more rapidly than the cost of storage so the cost-optimal amount of overbuilding increases. This sweet spot could change, and the amount of overbuilding required could decrease, if the cost of storage relative to solar decreases in the coming years.The additional renewable capacity in the over-building scenario is called “implicit storage”, as it effectively substitutes for storage.

This strategy is cost effective as compared to fossil fuels and “business as usual” because it is now cheaper to build an entirely new utility-scale solar farm and use the energy generated there than it is to operate and fuel an existing coal-fired power plant (Inside Climate News). The ever-decreasing cost of electricity from solar because of technological advancements and $0-cost fuel has eventuated a new paradigm in energy thinking. It’s the first time in human history that planning to overbuild infrastructure makes economic sense. In a 100% renewables future, the economic cost and the environmental impact are lower if we build more variable renewables than we need on an energy basis.

Because the results are quite surprising and new to many, they therefore provide crucial, new insight for RE planning purposes, as well as simply validating the claim that a 100% transition is both feasible and affordable. And as such, advocates of renewable energy should work to build public awareness of the potential for implicit storage to lower cost and hasten the transition to 100% renewable energy.


The International Energy Agency (IEA), founded in 1974, is an autonomous body within the framework of the Organization for Economic Cooperation and Development (OECD). The Technology Collaboration Programme (TCP) was created with a belief that the future of energy security and sustainability starts with global collaboration. The programme is made up of 6.000 experts across government, academia, and industry dedicated to advancing common research and the application of specific energy technologies.

The IEA Photovoltaic Power Systems Programme (IEA PVPS) is one of the TCP’s within the IEA and was established in 1993. The mission of the programme is to “enhance the international collaborative efforts which facilitate the role of photovoltaic solar energy as a cornerstone in the transition to sustainable energy systems.” In order to achieve this, the Programme’s participants have undertaken a variety of joint research projects in PV power systems applications. The overall programme is headed by an Executive Committee, comprised of one delegate from each country or organisation member, which designates distinct ‘Tasks,’ that may be research projects or activity areas.

The IEA PVPS participating countries are Australia, Austria, Belgium, Canada, Chile, China, Denmark, Finland, France, Germany, Israel, Italy, Japan, Korea, Malaysia, Morocco, the Netherlands, Norway, Portugal, South Africa, Spain, Sweden, Switzerland, Thailand, Turkey, and the United States of America. The European Commission, Solar Power Europe, the Smart Electric Power Alliance (SEPA), the Solar Energy Industries Association, the Solar Energy Research Institute of Singapore and Enercity SA are also members.

Executive Summary

Grid-connected solar power generation, either dispersed or centralized, has developed and grown at the margin of a core of dispatchable and baseload conventional generation. As the penetration of this variable resource increases, the management of the underlying core gradually becomes more complex and costly.

The challenge ahead for grid-connected solar is to evolve beyond the margin and the context of underlying conventional generation management. The present report focuses on the challenge of displacement of the underlying conventional generation core by proposing to transform intermittent variable renewable energy (VRE) resources such as solar and wind1 into firm, i.e. effectively dispatchable power generation.

Substantiated by in-depth case studies, this report infers that, almost anywhere on the planet, nearly 100% VRE power grids firmly supplying clean power and meeting demand 24/365 are not only possible but would be economically viable, provided that VRE resources are optimally transformed from unconstrained run-of-the weather generation into firm generation. VREs are then capable of entirely displacing all conventional sources economically (provided now emerging grid-forming inverter technology resolves any grid frequency and stability issues resulting from the displacement of conventional rotating power generation). The variable-tofirm transformation enablers include energy storage, the optimum blending of VREs and other renewable resources, geographic dispersion, and supply/demand flexibility. Most importantly this transformation entails overbuilding (see below) and operationally curtailing the VREs ─ a strategy we term applying implicit storage. This strategy ensures acceptable total VRE production costs, which include both generation and grid integration cost.


This paper received valuable contributions from several IEA-PVPS Task 16 members and other international experts.

Its authors are particularly grateful to Sophie Pelland (CanmetENERGY, Natural Resources Canada) for her careful review and suggestions.

Please see the full paper here.

Additional Resources

New Wind and Solar Are Cheaper Than the Costs to Operate All But One Coal-Fired Power Plant in the United States (Inside Climate News)

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