Bill Gates, co-chair of the Bill & Melinda Gates Foundation, is bullish on mobile banking.

A “low-cost digital debit card,” he said, along with the proper safeguards and reasonable fees, could transform the lives of billions of people who now lack access to basic banking services. Earlier this week, he told The Verge in the video below that he sees 2 billion additional users of mobile banking by 2030, mostly in parts of the world that never built traditional banking infrastructure.

As part of his philanthropic work, Gates has taken a lively interest in financial services for the poor, perhaps influenced by Kosta Peric, deputy director of financial services for the poor at the Gates Foundation. In an “Ask Me Anything” session on Reddit last week, Gates touted bitcoin as a potentially powerful tool for the poor, and hinted at the use of another digital currency by the Foundation:

Bitcoin is an exciting new technology. For our Foundation work we are doing digital currency to help the poor get banking services. We don’t use bitcoin specifically for two reasons. One is that the poor shouldn’t have a currency whose value goes up and down a lot compared to their local currency. Second is that if a mistake is made in who you pay then you need to be able to reverse it so anonymity wouldn’t work.

Overall financial transactions will get cheaper using the work we do and Bitcoin related approaches.

Making sure that it doesn’t help terrorists is a challenge for all new technology.

The Bill & Melinda Gates Foundation recently struck a deal with Social Money, the financial platform best known for its innovative SmartyPig savings account product. The Gates Foundation is using its deep pockets to quietly become a major force for financial innovation both in the U.S. and abroad.

Learn about online banks at Bank Innovation 2015 on March 2-3 in Seattle. Request your invitation here.