New innovations in energy storage, transmission, and the integration of variable electricity sources are necessary to enable renewable energy sources to contribute significantly to the U.S. energy supply, according to a new report from the American Physical Society.

Establishing national policies to spur the deployment and adoption of renewable electricity sources, such as wind and solar power, are important, but the scientists warn that research and innovation must also proceed in parallel on better energy storage technologies, new strategies for integrating the varying and intermittent output of these energy sources, and improved technologies for the long-distance transmission of renewable electricity.

According to APS:

[W]ithout the focus on storage devices, it will be difficult to meet proposed renewable electricity standards, the report asserts. Wind and solar energy are variable by nature: The sun doesn't always shine, and the wind doesn't always blow. The amount of electricity a consumer has available to complete household chores could change in a matter of seconds, hours or days--placing great importance on the need for robust storage methods.

Another challenge facing the grid involves the long-distance transmission of renewable electricity from places that receive a lot of wind and sun to those that do not. "We need to move faster to have storage ready to accommodate, for example, 20 percent of renewable electricity on the grid by 2020," said George Crabtree, co-chairman of the POPA study panel and a senior scientist at Argonne National Laboratory. "And, by devoting the necessary resources to the problem, I am confident that we can solve it."

The report addresses variability and transmission issues by urging the U.S. Department of Energy (DOE) to increase research on materials to develop energy storage devices and by encouraging the DOE to focus on long-distance superconducting direct current cables to bring renewable electricity to load centers, lessening the chance that power will be disrupted. The report also calls for examining renewable electricity in light of a unified grid instead of one that is fragmented and improving the accuracy of weather forecasts to allow for better integration of renewable electricity on the grid.

The report, titled "Integrating Renewable Electricity on the Grid," was released this week by the American Physical Society's Panel on Public Affairs. For more the the report's recommendations, see here.