Google co-founder Sergey Brin is spending more than $100 million to build the world’s largest airship, a blimp with a rigid structure designed to both deliver supplies abroad for humanitarian projects and ferry Brin’s family and friends around the globe, according to a Guardian report. The project is the latest example of Silicon Valley attempting to reshape how goods and people are moved. But it also, some say, underscores a penchant for tech moguls to color their projects with seemingly virtuous ambition.

Some people on social media seized on the vessel and its apparent dual purpose. On the one hand, it’s a benevolent carrier transporting food to remote, hard-pressed communities, and on the other it’s a luxurious “air yacht,” as the Guardian report described it, shuttling a billionaire and his inner circle to exotic locations.

Alphabet, Google’s parent company, declined to comment.

“A flying yacht that’s also going to do deliver assistance is long on the yacht part and a little short on the humanitarian aid part,” said Rob Enderle, technology industry analyst at the analysis firm Enderle Group. “I guess [Brin] was looking for a tax deduction. Maybe he can cut back on taxes and operational costs.”

The vessel is reportedly being built at the NASA Ames Research Center in Mountain View, Calif. When completed, the airship will become the world’s largest aircraft, at more than 200 meters long, although its payload is not known, according to the Guardian. Plans for the vessel, which is being funded by Brin, were first revealed by Bloomberg earlier this year.

Experts say that the use of airships could bypass the congestion and costs tied to transporting cargo via roads, railways and airports. But lighter-than-air travel presents its own challenges, like the need to steady the aircraft by offsetting the weight of cargo once it’s offloaded. While the potential success of Brin’s aircraft could encourage others to develop lighter-than-air technology, Enderle said he questions the practicality of using such vessels, with their slow air speed, and vulnerability to adverse weather and militants. “There are a lot easier ways to deliver aid using current technology,” he said. According to the Guardian, Brin’s vessel will use a series of internal bladders to stabilize its flight.

Brin began his plans to build the vessel about three years ago, according to Bloomberg. His fascination with airships was sparked by visits to the Ames Research Center, which is next to the Alphabet headquarters. Ames once housed the navy airship USS Macon, which spanned 239 meters, and was among the largest aircraft of its time in the 1930s.

Some of Silicon Valley’s novel charitable efforts have been criticized in the past, perhaps most prominently in the case of Facebook founder Mark Zuckerberg’s initiative, which aims to bring Internet access to the billions of people who don’t have it. Critics of say that even though the initiative aims to connect more people to the web, it does so by offering customers in the developing world only a narrow slice of the internet, with Facebook standing to gain new users and more personal data to collect. With altruistic motives but lucrative business prospects, some see Zuckerberg’s initiative less as a magnanimous Internet project than as a version of high-tech imperialism.

Zuckerberg’s $100 million donation to Newark public schools in 2010, and funding by the Bill and Melinda Gates Foundation to reform education have also come under fire for promoting projects that lack accountability and lasting improvements.

It’s unclear whether Brin’s airship will be put to commercial use. But Larry Page, CEO of Alphabet and the other co-founder of Google, has also taken a keen interest in innovative aircraft. Page has personally backed two flying-car start-ups, Kitty Hawk and Zee.Aero. Kitty Hawk’s flyer, a personal electric aircraft that hovers over water, will be available for purchase later this year.