It was an energizing speech.

Vice President Kamala Harris made a joke about green electricity during her commencement speech at the U.S. Naval Academy in Annapolis Friday.

"Just ask any Marine today, would she rather carry 20 pounds of batteries or a rolled up solar panel, and I am positive she will tell you a solar panel, and so would he," she said, before laughing.

Video shows the crowd’s reaction.

It came after she told electrical engineering graduates that they would be responsible for converting wind and solar energy into "combat power."

"You are electrical engineers who will soon help convert solar and wind energy into power, convert solar and wind energy into combat power," she said.

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Critics on Twitter were quick to note that solar panels generally still require batteries to store energy as it’s collected from sunlight.

Harris’ speech also touched on cybersecurity, the coronavirus pandemic and climate change.

She warned that cybercrimes like the recent Colonial Pipeline ransomware attack could present a new frontier in international conflicts.

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"Just think, a deadly pandemic can spread throughout the globe in just a matter of months," she said. "A gang of hackers can disrupt the fuel supply of a whole seaboard. One country's carbon emissions can threaten the sustainability of the whole Earth."

She also became the first woman to deliver the keynote commencement address at a Navy Academy ceremony.

Servicemen and women currently rely on high-tech lithium-ion batteries to power weapons, sensors and other devices during night operations.