Since the early days of the modern environmental movement, activists have embraced solar and wind power. A “small is beautiful” mantra guided a “ soft path ” to the renewables revolution.
That vision inspired an open letter sent last week by hundreds of grass-roots environmental groups to Congress demanding a rapid transition to 100 percent renewable energy and explicitly rejecting virtually all forms of emissions-free power except solar and wind. The letter (notably lacking the signatures of six of the major national environmental groups) is one of several competing efforts to define a Green New Deal, an inchoate idea that has recently captured the political imagination on the center and left.
The energy and ambition of this effort is certainly worthy of applause. But environmental leaders in Congress must recognize a hard truth. The Green New Deal will be no deal if all it buys us is solar and wind power.
A breakthrough on climate will depend on a willingness by Democrats and others to harness the well-intended ambition of activists while focusing on practical ways to take carbon out of our power system. Otherwise, Republicans won’t go along, and it won’t be feasible for the electric power grid.
Wind and solar have come a long way since the early days. These sources now produce about 9 percent of the electricity in the United States, and their costs have declined dramatically in recent years.
We can celebrate that progress without turning it into a narrow mandate. We recently reviewed 40 studies of decarbonization pathways, and the results could not have been clearer. Without exception, every study that sought to identify the most affordable clean electricity system without artificially constraining available technology options reached the same conclusion: It was much cheaper to include so-called firm low-carbon technologies such as nuclear, carbon capture, or reliable but often overlooked renewables like geothermal or hydro dams with large reservoirs, than it would be to build a clean energy system without them.
Firm electricity generation resources are available on demand, for any length of time, any season of the year. That makes them a critical complement to weather-dependent wind and solar, as well as resources like batteries or strategies like demand flexibility (which permits consumers to reduce their electricity use in periods when supplies are strained) that are best suited to fast bursts of use.
In other words, firm technologies complete the clean energy team. Wind and solar add value to the grid and can even be star players. But they aren’t cut out to win the decarbonization game all on their own.
Why? The variability challenge of renewables is greater than is generally appreciated. The problem is not simply the setting sun and the hourly dips in wind generation; the toughest challenge comes from the weeks and months when wind and solar production decline dramatically because of seasonal factors or prolonged weather fronts.
To get through those lengthy periods, renewables-dominated systems have to be supersized, installing three to eight times more power capacity than peak demand so they can fill the void when solar and wind output is diminished. That means they also produce way too much electricity when favorable conditions return. That excess is either wasted or stored (at a cost) for later use. And, presently, storage technologies are not available to do the job cost effectively at the scale we are talking about. If such a system were to be built, it would feature a lot of poorly utilized, capital-intensive wind, solar and storage assets. Unless the cost of those technologies falls to extremely low levels, we’ll be forced to choose between clean energy and affordability. The recent riots in Paris show how that conflict might play out.
Clean power systems with a mix of fuels can more easily match generation to demand and productively use all assets more often, making these systems more economical to operate. There’s no waste of large surpluses of energy or the need to develop seasonal energy storage. These advantages make the economics of a balanced low-carbon power system more attractive than those that rely solely on weather-dependent renewables. Maintaining fuel diversity also minimizes the zero-sum politics of an all-renewables grid. We don’t need to shutter the nuclear and fossil fuel industries to achieve environmental goals.
To be clear, firm energy technologies face daunting challenges of their own. No one believes it is easy to build nuclear or carbon-capture power plants, which would capture carbon dioxide emissions and utilize or permanently store them. Enhanced geothermal energy (which uses techniques similar to fracking to unlock renewable energy) is still an emerging technology. But the value of these resources to a decarbonized power system would be very high, justifying efforts to accelerate their development and deployment.
We are not alone in our conclusions. In his State of the State address Tuesday, Gov. Andrew Cuomo of New York deliberately outlined a transition to a 100-percent clean, carbon-free energy system by 2040 — not an all-renewables system. California recently did the same . When two of the most environmentally progressive states both see the wisdom of a broad path to decarbonization, activists would be wise to heed their pragmatic conclusions.
Expanding and improving the set of firm, carbon-free energy resources would make it much more affordable and feasible to eliminate greenhouse gas emissions from electric power plants. That’s something Green New Dealers and Americans of all political stripes could get behind.
Jesse Jenkins is a postdoctoral environmental fellow at Harvard. Samuel Thernstrom is the founder and executive director of the Energy Innovation Reform Project , and a senior fellow at the Center for the National Interest.
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