Seriously need help

I am building a water rocket powered boat for an engineering project. So I bought these 2.2L Argon gas tanks that i want to blow into a seperate chamber full of water that has a nozzle with a valve on it. The problem is that my 2.2L argon tank is at 100Bar of pressure. I know that this is way too much power for a maybe 8-10kg boat.

I sorta need to use these bottles since I paid for 3 of them and they are not cheap.