An 18 KW in natural gas is very much like a 20 KW in propane. Actually, natural gas is and not as powerful as propane. Propane is more powerful. If you have a 20 KW in propane, it will remain 20 Kw. In natural gas, it drops to 18 KW. It drops 2 KW. Some manufacturers have allowed for that drop and not industrial 30Kw Diesel Generator generator much. But, they are saying anything about it's. They won't talk about understand it. They are not letting it known towards public or through their dealers or manufacturers. They say it's capable and even the same. It's not at all the pretty same. The fuel burns differently. Propane burns hotter than propane so then it gives the engine less horsepower so therefore it's got less Kw.
Generators can figure with the usage of 200kw diesel generator, gasoline, and propane gas. Deciding on your one, you have to consider strength ? source is more practical and convenient.