Black or brown hydrogen is extracted from coal. Gray hydrogen is made by heating natural gas. Both create carbon dioxide. Blue hydrogen captures about 90% of that carbon dioxide and stores it, usually underground. Green hydrogen uses renewable energy to split hydrogen out of water using electricity. Pink hydrogen does the same but relies on nuclear power.
Meredith Miotke for NPR
Kenyan mountaineer James Kagambi (C), 62, is welcomed upon his arrival as the first Kenyan who reached the summit of Mount Everest, the world's highest peak of 8,849 meters, at Jomo Kenyatta International Airport in Nairobi, Kenya, on May 23, 2022.
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Green the Chow Chow sits in the grooming area at the 142nd Westminster Kennel Club Dog Show at The Piers on February 12, 2018 in New York City. The show is scheduled to see 2,882 dogs from all 50 states take part in this year's competition.
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ATLANTA, GA - MAY 21: People hold signs during a protest against recently passed abortion ban bills at the Georgia State Capitol building, on May 21, 2019 in Atlanta, Georgia. The Georgia "heartbeat" bill would ban abortion when a fetal heartbeat is detected. (Photo by Elijah Nouvelage/Getty Images)
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Abortion rights demonstrators gather near the Washington Monument during a nationwide rally in support of abortion rights in Washington, D.C., US, on May 14, 2022.
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An aerial photo taken in April 2020 shows the scenery of a giant karst sinkhole in China's Guangxi Zhuang Autonomous Region. A similar sinkhole was found earlier this month with an ancient forest at the bottom with trees towering over 100 feet tall.
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A COVID Memorial Project installation in September, 2020 marked 200,000 lives lost in the COVID-19 pandemic. The official death toll in the U.S. is on the cusp of a million.
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