The Nantucket Memorial Airport in the US state of Massachusetts has reopened its Memorial Terminal after a 20-month upgrade project.

The $29m project has modernised and expanded the terminal that caters to 500,000 people that travel through it each year.

The terminal is the first in the country to run on an HVAC geothermal system, which extracts power from heat stored in the earth instead of relying on fossil fuels.

The renovated terminal includes a 6,000ft² basement and 6,300ft² of office space.

Of the total cost, $12m was provided for by the Massachusetts Aeronautics Commission, the Federal Aviation Administration gave $11.5m, while the rest was paid by Nantucket Memorial Airport.