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Illustration of renewable energy sources

100% Renewable Energy: Can It Be Done?

Questline energy expert Mike Carter shares his analysis of renewable energy goals and the outlook for utilities.

Green energy is much more than a buzzword. Most Americans want their energy to come from renewable sources, and a growing number of utilities, regulators and even private companies are setting ambitious goals for phasing out fossil fuels.

Renewable energy includes sources that are naturally replenished on a human timescale, such as sunlight, wind, rain, tides, waves and geothermal heat. Two states, California and New York, have committed to mid-century goals to use only renewable or zero-emission sources.

According to Sierra Club’s Ready for 100 campaign, over 150 U.S. cities have adopted 100% clean energy goals. The Rocky Mountain Institute reports that more than 160 companies worldwide have committed to 100% renewables.

There are several challenges to this goal, however, including the fact that the sun does not always shine, the wind does not always blow, and ocean waves are not always present. To achieve 100% renewable energy would require either a significant increase in baseload renewable energy sources like hydropower or geothermal or some way to store excess power. An analysis of this challenge indicates that a 15-fold expansion in hydropower generating capacity would be necessary, which is not very likely.

Energy storage technologies such as lithium-ion batteries are feasible but still expensive, although costs are steadily dropping. While the U.S. is home to six of the world’s largest lithium deposits, lithium is presently sourced from Chile, Argentina, Bolivia and China. Safety concerns have driven the battery industry toward cell materials based on lithium iron phosphate, which is inherently safer than cells using cobalt. However, the tradeoff is lower voltage and lower energy density. Zinc-air battery storage technology, which is sourced domestically and inherently safer and much cheaper than lithium-ion, is now appearing in demonstration projects.

Achieving 100% renewable energy is technically achievable but will require strong political will, which is perhaps the biggest barrier. Renewable Portfolio Standards (RPS) requirements on utilities vary by state. Currently, 29 states, Washington, D.C., and three territories have adopted an RPS. Eight states and one territory have only set renewable energy goals.

The target range for share of renewables is usually 10% to 45%, although 13 states have requirements of 50% or greater. To assure diversity of renewable sources, many states have implemented minimum requirements (carve-outs) for specific types. Other states have incentivized certain technologies by awarding additional renewable energy credits (multipliers) for use of that technology.

Today, renewable energy production represents just 11.5% of all electric energy production. The share of renewable energy production is presently hydropower (40%), wind turbines (40%) and solar PV (9%).  The U.S. Energy Information Administration (EIA), however, projects electricity generation from renewable sources to surpass nuclear and coal by 2021 and natural gas by 2045. Solar PV is also expected to exceed wind by 2040.

The bottom line is the opportunity to provide energy infrastructure that is reliable, secure and affordable. Moving from “controlled” sources of power like fossil fuel-based power plants to “uncontrollable” renewable energy sources is a new paradigm. But maybe the journey to decarbonization is just as valuable as the destination.

Mike Carter is a Senior Engineer at Questline. He has a BS in Engineering and an MBA degree from Ohio State University and is a Certified Energy Manager.

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