Google once considered its own digital money system called Google Bucks, but scrapped it because of regulatory concerns.

Google Chairman Eric Schmidt is delivering a keynote speech at the Mobile World Congress trade show in Barcelona. A questioner asked him if he'd like to take a look at an alternate currency system he'd devised.

Schimdt answered by noting that most alternate currency systems are illegal, but other than that they're a great idea.

Regulators are most often concerned that alternate currency systems can be used for money laundering and trading in illegal goods. For instance, last summer New York Senator Charles Schumer called on authorities to shut down Silk Road, an online trading marketplace that accepted the alternative digital currency Bitcoin.

In his talk, Schmidt also said that he expects $70 smartphones to emerge next year, that people will want to move to Kansas City to take advantage of the super-fast fiber network Google is building there, and that self-driving cars are "a lot closer than you think."