Susan Phillips

President Joe Biden announced billions of federal dollars for the creation of regional hydrogen hubs across the country. Hydrogen could be a climate-friendly alternative to fossil fuels.

Beneath the streets of hundreds of North America's oldest cities lies a network of pipes delivering steam heat to office buildings and hospitals. These steam loops could be a clean energy solution.

"Steam loops" under hundreds of U.S. cities and universities have warmed buildings for a century. Now they could become a climate change solution.

Beneath the streets of hundreds of North America's oldest cities lies a network of pipes delivering steam heat to office buildings and hospitals. These steam loops could be a clean energy solution.

The Postal Service plans to replace about 160,000 gas-guzzling delivery trucks, but just a fraction will be electric. Advocates and states say going electric is aligned with climate change goals.

The Biden administration has opened the East Coast to massive offshore wind development. But it will happen in some of the country's most fertile fishing grounds, and that's set up a growing battle.

Fifteen states are challenging the decision, arguing that the risk of explosion puts lives in danger. For one project, highly flammable gas will travel 200 miles through a busy East Coast corridor.

U.S. cities are facing an increase in the number of homeless residents. The housing crisis in Philadelphia led to an unusual agreement to allow some homeless people to move into vacant houses.

Pennsylvania is a major state for drilling natural gas. President Trump has made fracking a significant issue of his campaign in the swing state, but it's unclear how much it may help him.

Across the country, new gas pipelines have met political opposition, protests and lawsuits. In Pennsylvania, one major project has also sparked criminal investigations.

Chemical experts say recent refinery explosions could have been far more devastating if deadly hydrogen fluoride was released. Some are calling for a ban on the chemical.

Japan doesn't think battery electric cars are the only future for transportation. It is investing millions to ramp up production of hydrogen fuel cell vehicles, citing their convenience for consumers.

The chemicals, which are linked to health problems, have contaminated drinking water and soil in many parts of the United States. Critics say the EPA is not acting fast enough to limit them.

Many major airports are on low-lying coastal land where flooding is getting worse. They're building walls, berms and other barriers to try to keep planes and people moving.

Close to 800,000 records from about a dozen plant collections or "herbaria" are being digitized, allowing researchers broad access to data on plant species collected and preserved in past centuries.

International shipping sometimes brings unwanted guests: invasive species. The latest invader, the spotted lanternfly, threatens fruit and hardwoods. It's recently spread to Pennsylvania.

With quiet persistence and an eye on economic solutions, businessman turned activist Jay Butera has helped usher in a small but truly bipartisan climate caucus on Capitol Hill.

The Environmental Protection Agency is a big target as President Trump aims to cut back the federal budget and workforce. Now some agency employees are organizing to defend the agency's work.

The Obama-era "Waters of the United States" rule defines which small bodies of water are subject to U.S. authority. Opponents such as farmers, homebuilders and golf course owners say it goes too far.

President Trump will sign an order on Tuesday that aims to roll back the Obama administration's Waters of the U.S. rule. It applies only to small bodies of water, but it has some big opponents.