Renewable Energy

National power grid could cut costs and carbon: Study

A unified, national power grid could be the cheapest and greenest way to keep the lights on in America.

This image of the continental United States at night is a composite assembled from data acquired by the Suomi NPP satellite in April and October 2012.
Source: NASA

Doing things like selling electricity from a solar farm in Texas to a household in a state farther north would be cost-effective — while cutting carbon emissions — if the United States were unified on a single power grid, according to a new study.

A team of researchers from the National Oceanic and Atmospheric Administration and the University of Colorado, Boulder, developed a computer model that designed the most cost-effective systems for delivering electricity across the United States, based on weather, land use and electricity consumption data. They found that an area as large as the United States would be best powered mostly by renewable energy sources linked to a single national electrical grid system.

Currently, power in the United States flows over a cluster of separate electrical grids that are maintained by many local or regional utilities. Replacing that arrangement with a single grid would allow the contiguous 48 states to depend more heavily on solar and wind energy and dramatically reduce carbon emissions, while keeping costs low and meeting projected demand increases.

"If you have this large area to trade electricity — because the wind is always blowing somewhere or the sun is shining — you basically get access to areas where wind and solar are cheap, in a national market," said Alexander MacDonald, co-lead author and recently retired director of NOAA's Earth System Research Laboratory (ESRL) in Boulder.

MacDonald said the study could act as a tool for policymakers, and he likens the idea of a national power grid to the national highway system that was begun during the Eisenhower administration.

"If we set up a national interstate for electrons, we would basically see a transformation to low-carbon energy without an increase in cost. That is what our study shows," MacDonald said.

The group published its findings in the journal Nature Climate Change on Monday.

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Co-author Christopher Clack, a mathematician at the Cooperative Institute for Research in Environmental Sciences at the University of Colorado, Boulder, said the team designed the model to pick only the most efficient designs in its simulations, without regard for environmental concerns or other constraints.

"We are completely agnostic about which technologies to pick," Clack told CNBC. "We just tell it to pick the cheapest costs for the grid. It turns out if you do that on a large scale, more and more wind and solar gets deployed."

The reason for this is that the large distribution area solves one of the biggest problems renewables have: they're intermittent. Unlike fossil fuels or nuclear power, solar cells and wind turbines produce power only when the sun is shining or the wind is blowing. Sometimes they produce more power than customers need, at other times they may not produce enough to meet demand.

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A fledgling energy storage industry and body of research has emerged to try to find a solution to the intermittency problem. MacDonald told CNBC that battery research is still a necessary and promising field, but the model his team designed does not require electricity storage.

Instead, as Clack said, the researchers' model "uses space and time as storage."

"If you can get these big-enough areas, you can transmit power across the grid more effectively," Clack said. "Just by doing that, you help reduce the intermittency of wind and solar."

The researchers built software that combines three things: land use data on where various types of power-generating facilities can operate; electricity use, and weather.

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The researchers' model compared the costs of commonly used electricity sources under various hypothetical scenarios. When the modeling program had a grid the size of the the entire contiguous U.S. at its disposal, it was able to place solar and wind farms in areas where they could best harness local climate and weather. The program placed solar farms in the sunniest regions — say in the Southwest — and wind farms in the windiest regions.

Essential to such a scheme would be the use of already available high-voltage, direct current (HVDC) transmission systems, which can send electricity over great distances — something the commonly used alternating-current system cannot do as efficiently.

Clack told CNBC that the cost of building the national grid system with HVDC technology was factored into the model. In fact, "the model could have chosen not to build any transmission, if it was most cost-effective to do so," Clack said. "But the model kept finding that transmission is the most effective way to share power across regions."

CNBC asked the Edison Electric Institute, a trade association for investor-owned utilities, for comment on the feasibility of a national grid systems. A representative for the association said the group had not yet read the study.