In December, San Diego became the latest (and largest) city in the United States to pledge to move entirely to renewable energy; in January, New York governor Andrew Cuomo launched a $5 billion clean energy fund; and this spring, lawmakers in Oregon are expected to vote on a measure banning the use of coal power.
Increasingly, U.S. states and cities are choosing to go out ahead of the Feds on climate action. But according to research published last month in the journal Nature Climate Change, building a sustainable green-energy future might still require Congress' help.
The study by researchers at the National Oceanic and Atmospheric Administration and the University of Colorado set out to determine whether it's possible, with existing technology, to create an electricity system that's both low-carbon and low-cost. The research returned promising results, with a caveat. According to the study, the U.S. could cut its electricity-related carbon pollution by nearly 80 percent without increasing consumer costs—but only by shifting from a regional electricity system to a national one.
Despite this asterisk, the findings represent a major breakthrough for renewable energy, which many scientists and economists had previously considered prohibitively expensive compared to coal and natural gas. According to recent studies, green-energy conversion had been expected to drive up consumer electricity prices by as much as 50 percent.
"A national system opens up a much more logical market for the placement of wind and solar generators."
But the problem with such numbers, says co-author Alexander MacDonald, is that they examine green-energy feasibility at the state or regional level, rather than on a national scale. MacDonald compares this approach to requiring every state in the country to manufacture its own automobiles. The system would be plagued by inefficiency and redundancy, making cars much more expensive. The same is true of electricity, which is why it makes sense to coordinate nationally and create an economy of scale.
"There are places where wind power is very cheap, and there are places where solar power is cheap," MacDonald says. "A national system opens up a much more logical market for the placement of wind and solar generators."
The study published last month examines the carbon and cost benefits of creating a national electricity system connected by high-voltage direct-current (HVDC) lines. This electricity "superhighway" wouldn't replace the country's existing electrical grid; instead, like the country's interstate highway system, the HVDC lines would add capacity to existing infrastructure, providing a direct connection between 32 regional hubs and allowing clean electricity to travel wherever it's in demand.
"The network doesn't replace all the stuff that brings electricity from the power plant to your toaster," MacDonald says. "It lays over the top and connects to the existing distribution system."
One major benefit of this approach is that it addresses renewable energy's reliability problem. According to previous studies, wind and sunlight, which are intermittent energy sources, aren't capable of meeting around-the-clock electricity demand without improved storage technology.
MacDonald says that remains true on a state and regional scale (because if the wind isn't blowing in eastern Colorado, it probably isn't blowing in western Colorado either). But the equation changes when renewable energy systems are built nationally.
"Weather has a size," MacDonald explains. "The question is how far you must go to reach a point where, even if the wind isn’t blowing in one part of the domain, it's almost certain to be blowing in other parts. The answer, we found, is the entire 48 states, because that's the size of weather."
Harnessing all that weather would reduce carbon reductions by between 33 percent and 78 percent relative to 1990 levels, according to the study. And those figures don't even account for possible market interventions, such as a federal subsidy for solar energy, which would skew the economics in favor of renewable energy. Instead, the researchers presume a free market in which electricity producers would select the most cost-efficient energy source, whether it's wind, solar, or natural gas. (Coal power, by far the dirtiest source of electricity, is excluded from the models, reflecting the study's big—but increasingly plausible—assumption that coal will be priced out of the electricity market altogether.)
Co-author Christopher Clack says that much of their modeling's uncertainty boils down to unpredictable market forces. For example, if natural gas prices stay low, electricity producers will naturally choose to use more natural gas than solar and wind energy, keeping emission reductions closer to 33 percent. But if gas prices rise quickly, renewable energy will become more attractive in the marketplace—an outcome that seems likely if coal continues to lose popular support and economic viability, driving demand to natural gas.
"All the projections show natural gas prices going up toward 2030," Clack says. "But there's big variance in what they say the exact prices will be."
The best-case climate scenario, according to the study, is that high natural gas prices and low wind and solar prices will spur a rapid shift to renewable energy, reducing carbon emissions by 78 percent by 2030. Meanwhile, with the help of the HVDC superhighway—which provides three-to-one cost savings compared to a regional network—consumer electricity prices would rise less than two percent above 2012 rates.
If the U.S. adopts a national HDVC system, emissions would drop by as much as 1.5 billion tons per year—a carbon benefit equivalent to taking all automobiles off American roads.
So what's holding back this green-energy future? The main answer, unsurprisingly, is politics. Much like cross-country railroad lines or interstate highways, an HVDC network would require coordinated planning by the federal government—an effort that would face fierce resistance from the coal and natural gas lobbies.
The good news, politically speaking, is that an electricity superhighway wouldn't necessarily require a supersized paycheck from the Feds. According to MacDonald and Clack, committing to a national green-energy strategy would likely create a market incentive for private companies to bid on HVDC lines in exchange for future income. That public-private partnership, similar to a toll-road system, would lower the start-up infrastructure costs paid by taxpayers.*
"There has to be a national plan, but it's up to policymakers how to implement that plan," MacDonald explains. "It could be implemented commercially."
The implications for climate change are immense. The electricity sector is currently the country's biggest polluter, releasing more than two billion tons of carbon into the atmosphere each year. But according to the study's projections for 2030, building an HVDC network would reduce those emissions by as much as 1.5 billion tons per year—a carbon benefit equivalent to taking all automobiles (including trucks, motorcycles, buses, etc.) off American roads.
"What our paper shows, with high confidence," MacDonald says, "is that the United States could have a low-carbon, affordable energy system, and we could have it fast."
But not without a national electricity market. "That's critical," Clack says. "If you want to keep costs low while mitigating carbon, you have to go for this large scale."
"Catastrophic Consequences of Climate Change" is Pacific Standard's year-long investigation into the devastating effects of climate change—and how scholars, legislators, and citizen-activists can help stave off its most dire consequences.
*Update — February 18, 2016: This article has been updated to correct a typographical error in one instance Christopher Clack's surname.