While articles in the academic journal Proceedings of the National Academy of Sciences don’t often provoke bitter fights on the pages of major newspapers, that was the case for an academic study about renewable energy published earlier this week.
The article was authored by 21 energy experts, many of whom previously published articles showing large amounts of renewable energy can be reliably and cost-effectively deployed. Their new piece challenges some assumptions used in a 2015 paper by Stanford professor Mark Jacobson and several co-authors. Jacobson’s paper argued that wind, solar and hydropower alone could cost-effectively produce enough electricity and hydrogen to meet essentially all U.S. energy needs by 2050.
The new article is an important contribution to the academic literature, as it correctly points out flaws in Jacobson’s 2015 work. The authors of the new paper are also correct that the scale and urgency of the climate change problem argues for using all cost-effective solutions.
The wind industry and other energy experts have never advocated that wind energy, or even renewable energy, should suddenly provide 100 percent of our energy at a national or continent-wide scale. Obtaining 100 percent of the nation’s energy from any one fuel source, whether nuclear, coal, natural gas, the sun, or the wind, is unlikely to be cost-effective or reliable.
As a result, the argument in Jacobson’s 2015 paper is in many ways a strawman. Rebutting it does not cast doubt on the value and importance of greatly expanding our use of renewable energy, a conclusion both sides agree on but that unfortunately has gotten lost in the noise of the debate.
The press loves to cover conflict, and some of the tone in the debate playing out in newspaper pages has not helped. Participants in the debate, and those reporting on it, should not distract from what should be a constructive conversation about how both sides can work together on their common goal of deploying renewable energy to cost-effectively and reliably reduce carbon pollution. In reality, there is not as much difference between the two sides as has been portrayed in the press, with wide support among experts and the published literature for the following key points:
-A large body of published research demonstrates that renewables can reliably and affordably provide a majority of our electricity mix.
-Greatly expanding renewable energy use forms the core of any effective strategy to combat climate change.
-A diversity of resources will be most cost-effective for achieving carbon reductions on the timeline required.
In fact, the former NOAA researcher who is the lead author of this week’s rebuttal published a journal article last year showing that, using wind and solar energy alone, the U.S. electric sector can reduce carbon emissions by nearly 80 percent within 15 years “without an increase in the levelized cost of electricity. The reductions are possible with current technologies and without electrical storage.” Other analyses, including published work by other co-authors of this week’s critical article, lends support to that conclusion.
Taking arguments to their logical extreme and debating a strawman argument risks confusing and distracting from these important and widely supported conclusions that should guide the path forward.
The path forward
A large body of analysis shows high penetrations of renewable energy can be achieved reliably and cost-effectively. As discussed above, a 2016 article by the lead author of this week’s critique found that perceived challenges with renewable output variability can be solved by aggregating large amounts of wind and solar resources over large geographic areas, because “Paradoxically, the variability of the weather can provide the answer to its perceived problems.” The National Renewable Energy Laboratory’s Renewable Energy Futures study found renewable energy can reliably provide 80 percent of U.S. electricity. Grid operators and national laboratories have also found high renewable penetrations can be reliably integrated at the regional level.
While powering an entire continent with 100 percent renewable energy can pose unique challenges, 100 renewable electricity can be achieved at the state or even grid operator level today. At times Denmark has exceeded 100 percent wind energy, while states like Iowa and Kansas have done the same. The company NaturEner has successfully operated a wind-only grid balancing authority in the Western U.S. for nearly a decade, using market transactions to accommodate fluctuations in wind energy output. These studies and real-world experience show that a large integrated power system and strong transmission system solve the challenges associated with integrating very large amounts of renewable energy.
A recent proposal in California to obtain 100 percent of the state’s electricity from clean energy is also achievable because the state plans to use a balanced portfolio of renewable resources and existing zero-carbon generation, such as hydropower. Plus California, as it has successfully done in the past, plans to gradually move to these higher levels in phased benchmarks over time through 2045. Finally, California is increasingly integrated into the Western U.S. power system, providing access to diverse resources that solve integration challenges.
Technological advances and changes outside the electric sector will also play an important role, particularly as entire continents move towards very high renewable penetrations. Electrification of transport, building heating, and water heating, which is essential to achieving carbon targets, also provides significant energy storage and dispatchable flexibility to the power system. The use of excess electricity to produce fuels that can be stored, distributed, and consumed using infrastructure that exists today is also highly promising for the same reasons.
For example, pilot projects have demonstrated that electricity and carbon dioxide captured from the air can be used to commercially produce synthetic gasoline and natural gas with zero net carbon emissions; hydrogen produced from renewable electricity could also have a role as an energy storage and delivery medium in some sectors of the economy.
Other technologies that are likely to be invented over the coming decades are almost certain to play a helpful role as well. Even under the most aggressive scenarios for renewable deployment, it is likely to be at least several decades before we reach the extremely high renewable penetrations at which these electrification solutions become essential for power system reliability and economics.
It is important to assess potential energy mixes of the distant future to determine that they contain no insurmountable barriers to cost-effectively and reliably meeting carbon reduction needs. Debating questions like whether renewable energy can cost-effectively provide 90 percent versus 95 percent of our energy mix, or the exact mechanics of how we will exceed 80 percent carbon reductions after the year 2050, may be interesting as an academic exercise. However, it’s far less important than making progress on the many urgent steps that must be implemented between now and 2050 if we are to effectively address climate change. Under almost any conceivable scenario, rapidly expanding the use of renewable energy is an essential step on that path. Any debate on that topic has been resolved; it is time for action.
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