Big block of copper. Water pumped through channels. The total heat output isnt all that big comparred to other water-cooled processes. A car engine cylinder pumps out more heat across a similar area. You will just need pumps and fans bigger than the toy parts used in normal pc cooling.
You just need a car radiator and engine.
Not really. A small automotive radiator, like on a motorcycle, can easily handle a few thousand watts. You just need a 200ish watt fan and a 100+ watt pump, not the sort of thing for home use but nothing extreme in the world of cooling products.