Wind and sunshine could power most of the United States by 2030 without raising electricity prices, according to a new study from the National Oceanic and Atmospheric Administration and the University of Colorado, Boulder.

Even when optimizing to cut costs and limiting themselves to existing technology, scientists showed that renewables can meet energy demands and slash carbon dioxide emissions from the electricity sector by 80 percent below 1990 levels.

The study, published yesterday in the journal Nature Climate Change, factors in energy demand, costs and, crucially, the role of weather.

Co-author Alexander MacDonald, outgoing head of the American Meteorological Society and recently retired from NOAA’s Earth System Research Laboratory, said the study sprang from discussions he had at the 2009 U.N. climate change summit in Copenhagen, Denmark.

“Basically, it was really clear that nobody has really looked at the importance of weather for wind and solar energy,” he said.

When clouds float overhead, gales slow to a breeze or both, solar panels and wind turbines slow their electricity production, forcing other generators to step up to meet demand.

However, MacDonald reasoned that over larger geographic regions, weather tends to average out, so spreading out renewables and channeling electricity accordingly could better smooth over peaks and valleys in electricity output.

“You really want to get an area big enough that, when wind isn’t blowing in part of it, it’s blowing in another part,” MacDonald said.

Pennies per kilowatt-hour
To answer the question of whether renewables could be a cost-effective energy solution, NOAA and University of Colorado scientists played to their strengths in weather analysis.

“NOAA has some of the best weather data around the world to look at this problem,” said Christopher Clack, a co-lead author and research scientist at the University of Colorado’s Cooperative Institute for Research in Environmental Sciences.

MacDonald, Clack and their collaborators developed a simulation called the National Electricity With Weather System (NEWS). The model incorporates weather and electricity demand in 60-minute increments over 13-kilometer blocks in the 48 contiguous states.

The model held nuclear and hydropower at 2012 levels, included land-use restrictions and demand growth, and projected energy production costs out to 2030, including production and transmission.

With an objective of reducing costs, researchers found that onshore wind and solar power could meet electricity demands at a levelized cost of energy comparable to 2012 levels, roughly 9.4 cents per kilowatt-hour.

In a scenario where renewables were more expensive than current projections, the model created an energy system in 2030 that cut emissions 33 percent below 1990 levels while producing electricity at 8.6 cents per kWh.

A scenario where renewable energy prices dropped and natural gas prices rose created a system producing electricity at 10 cents per kWh and cutting emissions by 78 percent.

As renewable energy takes up a larger share of the generation mix, large-scale weather effects end up reducing intermittency.

This challenges assumptions that more renewables on the grid would require more dispatchable generators like natural-gas-fired turbines or energy storage, both costly options for utilities.

Not waiting for a breakthrough
The NEWS model found that energy storage would not be cost-effective at current prices.

However, the Department of Energy earlier this month cast a ballot in favor of the conventional wisdom, issuing $18 million in funding for solar energy and storage research for utilities (ClimateWire, Jan. 20).

Representatives from the Edison Electric Institute and Electric Power Research Institute did not respond to requests for comment, citing weather-related office closures.

MacDonald and Clack said the key enabler for their high renewable energy penetration scenarios is high-voltage direct-current (HVDC) transmission. Photovoltaics and wind turbines often generate direct-current electricity, so transmitting in direct current removes a conversion step that costs money and saps power.

HVDC transmission lines also have fewer losses over long distances than alternating-current transmission. The authors envision an HVDC network across the United States akin to the interstate highway system, shunting power from where it’s produced to where it’s needed in a national electricity market.

In the model, transmission made up 4 percent of final electricity costs.

The study joins a growing suite of work finding that high renewable energy penetration is feasible in the United States (ClimateWire, June 10, 2015). Other studies have also found that energy storage isn’t the gatekeeper for drastically more wind and solar power on the grid (ClimateWire, Sept. 28, 2015).

MacDonald said this study is unique because it isn’t betting on a technology breakthrough and it sets its sights on 2030, while other studies set 2050 as the finish line.

“We’ll have doubled the CO2 by then in the air,” he said.

Reprinted from Climatewire with permission from Environment & Energy Publishing, LLC., 202-628-6500