ICMag with help from Landrace Warden and The Vault is running a NEW contest in November! You can check it here.
Prizes are seeds & forum premium access. Come join in!
No matter how much soundproofing, the constant noise and smell (Diesel exhaust that is, natural gas or propane might pass) will arouse someone's curiosity.
You should always use a hydrocarbon detector (about $75 at marine supply shops) to monitor the air around an enclosed unit for an explosive condition (referred to as the "lower flammable limit" or lower explosive limit). Unfortunately those units are generally used to shut the equipment down to prevent an explosion or fire. A good thing, but your lights are out at that point.
The 1800 RPM and 1200 RPM diesel units will run a long time as the engine is "loafing", however you will need to change the oil weekly and expect to rebuild the engine on whatever the manufacturer's recommended interval. (I've seen some that need checked for a valve job every 2000 hours)
Check-out marine (boat) generators if you're serious about trying it. They're designed and built for nearly constant use.
Still, unless I had a natural gas well and got my gas for free (and they still meter the usage!!) I would have to think long about doing a generator grow. Fuel costs, transportation, noise, maintenance, etc.
On the other hand, having back-up power can be a good thing. Avoid 3600 RPM units at all costs. Pay more for an 1800 RPM generator and you won't regret it.