Keurig's cold-drink maker has to chill, carbonate, and flavor water in 90 seconds - here's how it works

Keurig Green Mountain's next big thing is its cold-drink maker.

Called the Kold, its going to be rolled out nationally next year. Right now its available on the company's website and in a few retailers.

Keurig faces a saturated market for its hot drink brewing machines, which means a lot is riding on the Kold - which can deliver a carbonated, chilled beverage in 90 seconds without using a CO2 canister.

That trick could give the Kold an edge over rivals like SodaStream.

There's a lot of technology - and money - behind this. The company filed more than 50 patents, and has another 100 applications pending, over the course of five years as it developed the system. Keurig invested about $100 million in the device in fiscal 2015, and said in September it planned to spend a similar amount in 2016.

Critics of the Kold have been quick to point out some big flaws in the device: it's expensive, large, needs to get warmed up and isn't more convenient than popping open a soda, according to some complaints on Keurig's website and Facebook page.

But a closer look at how the device works also reveals a few hints to how Keurig might be able to do to address some of these issues.