Final answer:
The main claim of the passage is that the U.S. can substantially lower its carbon footprint by installing solar panels on government buildings, due to solar energy's lower carbon footprint and high potential to meet energy demands.
Step-by-step explanation:
The main claim being made in the passage is that by installing solar panels on all government-owned or operated buildings, the United States could significantly reduce its carbon footprint. Solar energy sources have a much lower carbon footprint compared to fossil fuel-based sources and are a sustainable alternative capable of meeting the nation's energy demands. Additionally, there are numerous benefits associated with solar power, such as the minimal impact on land resources when installed on rooftops and its abundant potential, as only a small fraction of the Earth's surface area would need to be covered with photovoltaic panels to satisfy global energy consumption.