Bill and Melinda Gates’ to-do list will probably put yours to shame. This year, in the Gates Foundation annual letter, the duo outlined their long-term, 15-year roadmap for the challenges that they want to solve. Their four main goals:

• Health: Reducing the number of children who die before the age of five and the number of women who die in childbirth while eradicating diseases like polio.

• Farming: Educating farmers and advancing farming techniques to curb malnutrition and reduce poverty levels.

• Finance: Bringing mobile banking to developing countries to help people secure and make spending and sharing money easy.

• Education: Using smartphones and tablets to bring online education to the poor while empowering women and teachers.

Ambitious is an understatement for the list, but it doesn’t mean it’s unachievable. Whether its drinking purified poop water to draw attention to sanitation problems or helping India eradicate polio, the Gateses have always had a way of putting the spotlight on a few of the world’s problem and bringing government, media and philanthropical attention to it.

This year, though, Bill and Melinda are shifting from backing micro-finance organizations that empower small entrepreneurs to bringing banking to all — from the farmer who keeps his value in livestock to the family that keeps their money stuffed under a mattress. And it won’t be done by installing a Wells Fargo in every corner of Africa.

As they wrote:

“The key to this will be mobile phones. Already, in the developing countries with the right regulatory framework, people are storing money digitally on their phones and using their phones to make purchases, as if they were debit cards. By 2030, 2 billion people who don’t have a bank account today will be storing money and making payment with their phones. And by then, mobile money providers will be offering the full range of financial services, from interest-bearing savings accounts to credit to insurance.”

And while bitcoin believers have long been touting the power the digital currency could have in transforming remittances and payments in developing countries, that’s not the solution Bill Gates has in mind — although it is a starting place. “We need things that draw on the revolution of Bitcoin, but Bitcoin alone is not good enough,” Bill Gates told Backchannel.

Specifically, he cited bitcoin’s inability to reverse or recall transactions — you can only send bitcoin back to someone if you complete another transaction — and the lack of attribution, which many proponents view as a plus. Gates also seemed wary of bitcoin’s price fluctuations, which 2015 has already shown can plunge bitcoin down 20 percent one day to only have it spike the next.