The existing Haber Bosch process prefers to run at 100% but it's possible to throttle it down to around 20% of the normal reaction rate without cooling the system, which would potentially result in catalyst poisoning and metal fatigue. It's possible in the thermo-mechanical realm, but I think not so easy to sell it in the financial.

Why would you build a $100M facility next to a wind farm and run it 85% of the time and only get 40% utilization through the year when you could build next to a dam and get 100%?

There is something to be said for setting up such a system to run on overnight generation but I've not yet dug deep into wind production information to know how much of the off hour production is going to waste. If operators really are paying to have excess electricity hauled away perhaps it would be a good thing to make ammonia on a variable basis.

http://knowledgeproblem.com/2008/12/16/more_on_wind_po_1/

Why would you build a $100M facility next to a wind farm and run it 85% of the time and only get 40% utilization through the year when you could build next to a dam and get 100%?

You'd build a $100m facility next to a wind farm because of access to cheap electricity part of the time, and buy the power from the Electricity Superhighway the balance of the time.

Of course, that assumes the existence of the Electricity Superhighway. And then the 5% line loss between the dam and the plant will cost much more per kWh than equivalent 5% line loss if built near the dam and buying cheap power from the wind farm via the Electricity Superhighway when the wind is strong. So you'd still locate near the dam.

You'd throttle demand for power based on current cost based on the trade-off between operating costs and capital costs ... and for the current technology, that trade-off likely says very little excess capacity can be purchased with the operating cost savings of increasing the share of ammonia produced with less expansive power ... which is why the lower capital cost technologies for ammonia production are intriguing.

Interruptable power will get you a much better rate. How fast can an ammonia plant electrical load be ramped up or down? If load can be dropped off or picked up quickly enough the utility might give a much better rate for power. Going from 100% load to 20% load in under a minute would be very valuble. The lower cost of the electricity might make the plant competitive. A large industrial load that can be picked up or dropped off quickly is as good as a gas turbine for load leveling. Bonneville Power has a program to pay industries to reduce load in critical periods, which is cheaper than buying peaking power in certain areas (especially the Olympic peninsula in Washington).

Where can I get more information on the power stuff? That sounds really interesting ...