One exception to note: If the food's sitting in an environment where the temperature is over 90Â°F, the USDA says the food should only be left out for one hour, so keep an eye on the clock if you're serving food on a hot day!
Estimated cost of hydrogen per kilogram in a variety of scenarios. With all of this in mind, here are the cost estimates per kilogram (which each include $1.25 for taxes): Hydrogen from natural gas (produced via steam reforming at fueling station). $4 â $5 per kilogram of hydrogen.
Rating Newest Oldest. Best Answer: Liquid hydrogen ranges in prices depending on how it is made, who makes it, and how much you buy. Typical present costs seem to be around $5.50 per kg. The density of LH is 0.07 kg/L, so this would be about $0.40 per litre, or about $1.50 per gallon. It really isn't all that hard to get LH, if you are willing to buy 200 L at a time.