The global energy system faces the profound challenge of transitioning from fossil fuels to clean sources while maintaining reliability and affordability. Whether 100% renewable energy can power the world is a complex engineering and infrastructural puzzle, not just a matter of resource availability. Achieving this goal requires overcoming three major hurdles: harnessing the sheer volume of energy needed, managing the inherent variability of natural sources, and overhauling the systems that deliver and consume energy. The possibility of a fully renewable world hinges on the successful, simultaneous deployment of new generation, storage, transmission, and end-use technologies.
Assessing Global Renewable Energy Potential
The technical potential of renewable energy resources significantly surpasses the world’s current and projected energy needs. Studies confirm that solar, wind, geothermal, and hydropower could generate electricity far exceeding global consumption. The theoretical capacity for renewable electricity generation is estimated to be between 6.6 and over 1,100 times the world’s 2021 electricity consumption, establishing technical feasibility.
Solar and wind power represent the largest portion of this potential, with utility-scale installations alone having a technical capacity greater than 100 PWh per year. This indicates that the primary limitation is not the resource itself, but the logistical and economic challenge of converting that energy into usable electricity and delivering it to consumers. Geothermal and hydropower sources provide a smaller, yet stable, contribution to the overall mix. Achieving a 100% renewable system requires a complete build-out of the harvesting and delivery infrastructure.
Solving the Intermittency Challenge
The inherent variability of solar and wind power, known as intermittency, is arguably the most complex technical obstacle to a fully renewable grid. Since the sun does not always shine and the wind does not always blow, a reliable energy system requires balancing supply and demand across all time scales. This balancing act is addressed through an integrated approach involving energy storage and system flexibility.
Energy storage systems are foundational to bridging the gap between generation and consumption. Short-duration storage, primarily lithium-ion batteries, manages fluctuations over minutes to hours, such as smoothing power output or providing immediate frequency regulation. These batteries are crucial for maintaining immediate grid stability and absorbing short bursts of excess power.
For longer periods without sun or wind—spanning days or even weeks—long-duration storage technologies are under development. Solutions like pumped hydro storage and compressed air energy storage offer mechanical means of holding large amounts of energy. Emerging technologies like green hydrogen are being pursued for seasonal storage, produced by using excess renewable electricity to split water. Green hydrogen can be stored in large quantities and later converted back to electricity or used as a fuel.
System flexibility is also enhanced through demand-side management, which involves shifting energy use to match the available supply. Demand response programs incentivize consumers and businesses to adjust their electricity consumption during peak demand or low-generation periods. Furthermore, advanced forecasting tools utilize artificial intelligence to predict renewable output with greater accuracy, allowing grid operators to prepare for fluctuations and optimize the use of stored energy.
Rebuilding the Energy Transmission Infrastructure
Transitioning to a 100% renewable system demands a complete transformation of the existing electric grid, which was designed for centralized fossil fuel plants. The new system must connect remote, resource-rich areas to distant population centers, requiring a massive infrastructural overhaul. Estimates suggest that the transmission network may need to double or even triple in size to accommodate the growth of wind and solar resources.
This expansion necessitates the widespread adoption of high-voltage direct current (HVDC) transmission lines. HVDC technology is more efficient for transmitting large amounts of power over vast distances with minimal energy loss. This makes it ideal for connecting offshore wind farms or remote solar arrays to urban load centers, supporting the development of a continental or global “supergrid.”
A macro grid concept utilizes interregional transmission to reduce the overall need for local storage and generation capacity. By connecting regions with different weather patterns, variability is naturally smoothed out. This extensive network must be integrated with smart grid technologies that enable decentralized power flow and two-way communication, managing power from millions of distributed sources like rooftop solar installations.
Decarbonizing Non-Electric Energy Demands
Achieving 100% renewable energy requires addressing large sectors of the global economy that currently rely on direct fossil fuel combustion. These hard-to-abate sectors include heavy industry, long-haul transportation, and residential and commercial heating. The strategy involves both direct electrification and the use of alternative green fuels.
Direct electrification is the primary approach for many applications, most notably heating and personal transportation. Switching from gas furnaces to electric heat pumps and the mass adoption of electric vehicles transfers significant energy demand onto the electric grid. Industrial processes requiring low-to-medium temperature heat are also increasingly utilizing industrial heat pumps and resistance heating powered by clean electricity.
Decarbonizing Heavy Industry
For heavy industry, such as steel, cement, and chemical production, alternative fuels are often necessary. Steelmaking can be decarbonized by replacing coal with green hydrogen as a chemical reducing agent or by using electric arc furnaces powered by renewable electricity. Cement production, which has unavoidable process emissions from heating limestone, is focusing on carbon capture and storage or substituting clinker with non-fossil materials.
Alternative Fuels for Transport
The long-distance transport sector, including maritime shipping and aviation, requires zero-emission liquid fuels. Green methanol and ammonia are emerging as leading candidates for shipping; ammonia contains no carbon, while green methanol can be a net-zero fuel if produced renewably. For aviation, the focus is on sustainable aviation fuels (SAF) made from biomass or synthetic fuels (e-fuels) created by combining captured carbon dioxide with green hydrogen. These alternative fuels are essential where the energy density of batteries is insufficient for operational demands.