a reactor vessel at about 1,000°C.
using a metal catalyst under high temperatures and pressures:
Michael Pollan pointed out that the principal ingredient in all foodstuffs is corn, and that the principal ingredient in corn is oil. 800 trillion BTUs in fossil fuels for American agriculture in 2012 - granted, US total energy use in 2017 was 97 quadrillion BTUs but "fixating nitrogen" is an energy intensive process no matter how you slice it.
I think you need to drive down the Grapevine into LA amongst all the food trucks and look West and see the giant pipes pumping water uphill to Los Angeles to really get how much energy it costs to be alive these days.