IMAGE: Gage Skidmore

100% Renewable Power Feasible for U.S.,

New U.S. National Lab Study Says It Won't "Break the Bank"

John J. Berger Ph.D.

Sustain Europe U.S. Correspondent






September 21, 2021

In the race to reach carbon neutrality sooner rather than later, transitioning to renewable energy is key. Some countries are well on the way: our cover star country, Iceland, already gets almost all of its electricity from renewable sources. Albania is at 100%. Norway is close to 100% renewable power and Denmark is not far behind at 80%. Other European countries are making big strides and outside Europe, the Democratic Republic of Congo, Uruguay, Paraguay, Costa Rica and Brazil are leading the way on renewable energy. But is this change coming at a huge cost to the consumer? No. According to U.K. climate think-tank Ember, countries with large renewable energy fleets usually pay less for their electricity than their fossil-fuelled neighbours. The U.S, however, used fossil fuels to generate 60.3% of its electricity in 2020. So, can this bastion of fossil-fuel power go 100% renewable? Our U.S. Correspondent looks in depth at a new study suggesting it's both practically and financially feasible.




Creating a 100 percent renewable energy power system in the U.S. is feasible with existing technologies, and even a very high degree of renewable generation can be achieved cost-effectively, according to a new study. Moreover, a future grid powered with 90 percent renewable energy should cost about the same as today's 20 percent renewably powered grid.


These are the surprising conclusions of a major new U.S. government modeling study published in Joule. “Quantifying the Challenge of Reaching a 100% Renewable Energy Power System for the United States.”


All this is good news for the Biden Administration which has set a target of a decarbonized power grid by 2035. The Administration also has announced the goals of a 50-52 percent economy-wide reduction in net carbon emissions by 2030,1 and a net-zero-carbon U.S. economy by 2050.2


The study found that costs per kilowatt-hour rise very steeply for the last few percent of the renewable power additions needed to bring the grid to 100 percent. Those marginal costs, however, do not greatly impact the average cost of a 100 percent renewable power grid.


Raising the percentage of renewable power on the grid from 20 percent to 57 percent would result in an average levelized system cost of only $30 per megawatt (million-watt) hour.3


Although the incremental per megawatt-hour cost of going to 100 percent would be higher, it would on the average only be 29 percent higher, rising by only $10 per megawatt-hour, the equivalent of a cent per kilowatt-hour.





This graph from “Quantifying the Challenge of Reaching a 100% Renewable Energy Power System for the United States” shows

that the average cost to eliminate a tonne of CO2 emissions by increasing the renewable power on the grid is only a few dollars

per tonne compared with the costs when renewable energy (RE) provides 57 percent of the grid’s power. That slight increase

continues until RE produces 90 percent of the grid output. At 100 percent RE, the average levelized cost per incremental tonne of CO2 abatement is still under $100 per tonne.


The new findings help dispel the view common from the 1970s to 2000 and beyond among utility experts, engineers, and other scientists that it would be virtually impossible to use more than 20% renewable energy on a power grid without making it unreliable.


Nuclear power advocates for decades also vigorously dismissed the idea that renewables could cost-effectively provide a high proportion of a grid’s power. This view was then frequently used as an argument for accelerating nuclear power deployment.


The complex, newly published federal government simulation research examines 154 possible scenarios for transitioning the contiguous U.S. up to 100% renewable electricity and calculates their respective costs and value.


The variability of wind and solar generation and the need to integrate them on the grid with energy storage and with other less variable renewables, such as hydropower, biomass, geothermal, and potentially with hydrogen, complicates the analysis.


The research was performed by the U.S. Department of Energy’s (DOE’s) National Renewable Energy Laboratory (NREL) and DOE’s Office of Energy Efficiency and Renewable Energy.


“Getting all the way to 100% renewables is really challenging in terms of costs, but because the challenge is nonlinear, getting close to 100% is much easier,” said Wesley Cole, lead author of the Joule paper.


The study is part of an in-depth, ongoing federal research program to delineate an optimal pathway to a fully renewable, zero-carbon electric grid. The study utilizes the results of another recent DOE/NREL study also published in Joule, What We Know—and Do Not Know—About Achieving a National-Scale 100% Renewable Electric Grid.




Total bulk power system cost at a 5% discount rate (left) for the seven base scenarios and levelized average and incremental CO2 abatement cost (right) for those scenarios. The 2050 renewable (RE) generation level for each scenario is listed on the x-axis. The purple diamond on the y-axis in the left plot indicates the system cost for maintaining the current generation mix, which can be used to compare costs and indicates a system cost comparable to the 90% case.

Source: NREL.4


NREL, Northern Arizona University, and Evolved Energy Research in January 2021 also issued a related study, part of a series of reports on greater electrification of the U.S. economy (which makes it possible to power more of the economy with renewable power).


The latest report in the series is titled, Electrification Futures Study: Scenarios of Power System Evolution and Infrastructure Development for the United States



In conclusion, an important finding of the first Joule study above (“Quantification. . .”) was that most of the costs for the renewable grid were capital costs and that future reductions in those costs could drive the overall renewable power system costs down further.


The study’s modeling revealed that the faster the transition to renewables went, the higher the costs incurred but the greater the cumulative CO2 emissions reductions.


The researchers also found that even though the costs of providing the last increments of renewable power to the grid were high—caused mainly by the need for that power to be provided in the form of reliable “firm capacity” (not subject to variations in wind, sun, or water flow)—those final units of renewable power could more economically be supplied by combustion turbines fueled by renewable biodiesel, synthetic methane, or “green” hydrogen in the future than by wind and solar.


Finally, the researchers saw a need for additional research on ways to further reduce system costs through the study of the scaling up [of] supply chains and “social or environmental factors that could impact real-world deployment,” as an NREL news release put it.








1 Relative to 2005 U.S. aggregate emission levels rather than the more often used lower 1990 emission levels.

2 White House Fact Sheet: President Biden Sets 2030 Greenhouse Gas Pollution Reduction Target Aimed at Creating Good-Paying Union Jobs and Securing U.S. Leadership on Clean Energy Technologies, April 21, 2021.

3 Equal to $0.03 per kilowatt-hour, a very competitive rate.

4 "The Challenge of the Last Few Percent: Quantifying the Costs and Emissions Benefits of a 100% Renewable U.S. Electricity System,"


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