Part of my job includes an annual Sustainability Report, and unfortunately for me, part of it involves math, which I suck at. Of course, the operations guys ask ME if their conversions are right, and I have no idea.
So, can you please yay or nay if the following conversions are correct:
1 Cubic Foot of Natural Gas = 1030 Btu’s
1 Gal of # 2 Fuel Oil = 139,000 Btu’s
Thanks!
ETA: Need answer quickLY. Sheesh.
Those look very close, from:
http://www.onlineconversion.com/energy.htm
I got
1 gallon [U.S.] of distilate #2 fuel oil = 138 874.158 23 Btu
0.01 hundred cubic foot of natural gas = 1 030.466 726 9 Btu
HTH
Also check out the table on page 2 of this column by Don Lancaster.
Natural gas is usually slightly more than 1000 btu/cf. (A quick cruise around the internet got returns of 1015, 1020 and 1027.)
The quality of natural gas varies somewhat from place to place, contact your utility if you need a precise number. They might be online.
You should also incorporate the concept of exergy into your analysis. A joule of fuel oil energy, for example, is not worth the same as a joule of natural gas energy.
What pressure is the natural gas at?
I believe the common unit of measure is the standard cubic foot, which is a cubic foot of the gas held at standard temperature & pressure. The mass is then a fixed figure with a chemical energy as described above, and there’s no additional energy to be extracted by mechanically expanding the gas.
Ah, thank you. I figured it had to be equated to a volume at some STP, but nowhere was this explicitly said.
If it makes you feel better, extreme accuracy is probably not required for a sustainability report. Nobody reads them and makes major decisions off of them, and it has yet to be proven that sustainability reports are market movers.
I’d just make sure you’re ballpark right and move on to the next set of metrics you need to gather (water usage, carbon footprint, etc).
Really being serious here. I worked on one once doing exactly what you’re doing(only trying to figure out tons and tonnes conversion). Sustainability reports are far more important as corporate communication platforms than technical manuals. Anyone who attempts to use it as a technical manual gets what they pay for (hint, they’re free).
Best of luck!
Thanks guys - I just let the guy use the conversions he proposed using.
Yeah, I know it doesn’t have to be perfect, but I wanted to make sure I was at least ball park!
Um…you should at least check on whether you are looking at lower (net) heating value, or higher (gross) heating value, as those 4 hydrogen atoms in methane soak up a lot of latent energy when they convert to water. This will throw off your calculations by about 10% or so. Some countries ONLY use net, some ONLY gross, and others use a mix-match of both. If nothing else, whichever you pick should be specified for scientific accuracy.
Una, I have no idea what you’re talking about! I’m so not science minded! Sorry.
What Una is saying is that hydrogen burns to form water. The water is usually lost to the smokestack and discharged to the atmosphere, taking around 1000 BTU’s per pound of water with it. The net heating value takes this loss into account.
Correct…the takeaway if you don’t want to get into the science aspect of it, is you need to note somewhere that 1,030 Btu/scf is a heat content on a gross (higher heat content) basis. Folks will understand what you mean. If however you are writing your report for an international audience, you may want to consider using net/lower heat content, which would be about 930 Btu/scf.