How about using spent grains to generate methane to run the kettle?

I toured the Maker's Mark bourbon distillery in Kentucky a couple weeks ago.

Their mash tuns hold 11,000 gallons each, so they got the economy of scale thing going. My tour guide (Susan) mentioned they stick all the spent grains in a "bio-reactor" where "anerobic bacteria" break down the spent grains and generate methane. They are able to run the whole plant without any other fuel, apparently.

The methane generator wasn't on the tour, but I am curious to know how such a peice of gear would look or be built.

If I got, say 15# of grain spent in an AG batch, what would it take to save a little propane next time around? I am guessing the microbes work best at or near STP, but the burners will work best with the pressure cranked up to several atmospheres. How would I do that? Where is the $$$ tipping point? How much space would this take up in my garage?

Thanks.

I'm not positive, but I suspect they are simply composting the grains and then capturing the methane (and probably compressing it) and then using that instead of NG.

A quick google turned up this: DIY Methane Generator

Anyone who has accidentally forgotten to clean out their mash tun has actually inadvertanly done this. Apparently the stench is enough to lose lunch.

Some report internal methane production after mass consumption of homebrew, perhaps this could be collected as well to supplement the composting grains.

Best of luck in your quest for a methane powered brewery.

Handy lionk, thanks Jeff. I vaguely recall now a French system where they would build a pit of cinderblock about 12x12x12 feet and fill it with alternating layers of wood chips and perforated hose. Then a tarp. The methane ends up in the hose. Somehow they were getting the methane out and heating a building with it.

Looking mroe like an outside shed project and less like a garage project.

maybe we should figure out a way to do this on our scale and next Earth Day we have a 100% green brew!

As I chew on it I am wondering about maybe running a water heater with the stuff so I don't have to store a bunch of methane until I get around to brewing my next batch.

Shouldn't be too difficult to feed the burner homemade methane if I have it or let it run on gas company gas if I am out.

I think the tour guide misled or you misheard the story. No way can they generate enough gas to power the process from the spent grains. Don't take my word for it - just read from the designer of the system:

"The new facility will anaerobically treat the liquid portion of the whole stillage and process waters produced during bourbon-making, generating methane-rich biogas, a renewable energy source, which will offset between 15% and 30% of the facility’s natural gas consumption. "

I would imagine they're just about breaking even on the process, pre-tax. Throw in some tax credits for turning a waste product into fuel and you're making money.