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.
1 Lower output and/or mid-efficiency gas boilers cost $2,500 to $5,000 installed; higher output and/or high-efficiency gas boiler replacement cost is $5,000 to $10,000 or more.2  This price should include removal and disposal of the old boiler. Lower output and/or mid-efficiency gas boilers cost $2,500 to $5,000 installed; higher output and/or high-efficiency gas boiler replacement cost is $5,000 to $10,000 or more.