Steel energy estimates

[calmc]

Process heat (including boiler) estimates are ~ 601 TBtu, compared to 2014 MECS estimate of 892 TBtu (292+45 [natural gas]+11 [coal, coke, and breeze]+544 [other] from table 5.2 (energy by enduse). Note that table 3.2 (fuel consumption) reports 290 TBtu for coke and 255 TBtu for other.

Fuel breakdown from calculated data:

Fuel	TBtu
Coal	3
Coke_and_breeze	10
Diesel	0.04
LPG_NGL	0.04
Natural_gas	374
Other	212
Residual_fuel_oil	0.83

Issue is what explains the ~300 TBtu under estimate?

Could there be an error in the the way blast furnace gas energy is estimated from GHGRP emissions (tier 2 methodology)?

[calmc]

There are two instances in 2014 of facilities (1000274, 1005615) reporting values for scf/year and MMBtu/scf for blast furnace gas and coke oven gas. The results emissions factors are lower than the default EPA value for BFG (~182 kg CO2/MMBtu vs. 274), but higher for COG (~36.5 kg CO2/MMBtu vs 46.85).

GHGRP energy calculation code ghg_tiers_IPH.py has been updated to use reported values for these facilities. However, this correction doesn't substantially close the gap with MECS data.

[calmc]

Maybe something in MECS methodology:

MECS analysts have assumed for purposes of estimation that all energy sources used for fuel are completely consumed in the process. That means that an energy source used as fuel will not be transformed into another substance that can later be used for fuel or nonfuel purposes. The assumption holds well enough in most cases even though waste substance that was not consumed in the heater or boiler may accumulate. In the case of a blast furnace used in the iron making process (NAICS 331111), the effect of not completely consuming the blast furnace fuel inputs may be a significant cause of duplication. Literature reviews and consultation have revealed that most of the formation of the blast furnace gas would arise from the input fuel use of coke. Other sources may contribute to the generation of blast furnace gas, but they appear to be minor compared with coke.

One possible solution to adjusting the MECS data so that the energy flows in NAICS 331111 appear reasonable is to adjust the fuel use of coal coke downward by the heat content of the blast furnace gas consumed in that industry. As implied in the preceding paragraph, this adjustment would be imperfect because not all of the blast furnace gas would necessarily arise from the incomplete combustion of coal coke. Another complication is that the MECS has historically published only a combined estimate for coke oven gas and blast furnace gas to meet publication requirements. However, the proportion of blast furnace gas in those combined estimates has been about two-thirds. Therefore, for 2014, an estimate for coal coke fuel use in NAICS 331111 in 2014 may be computed as: Coke and Breeze Fuel Use for NAICS 331110 as reported in MECS: 290 Trillion Btu (Table 3.2 in 2014 MECS). Coke and Blast Furnace Gas Combine Estimate in NAICS 331110: 234 Trillion Btu. (Table 3.5 in 2014 MECS). Adjusted Estimate for Coke and Breeze Fuel Use in NAICS 331110: 290 - 2/3(234) = 134 Trillion Btu.

[wxi1995]

The coal used to make coke has the greatest effect on total energy consumption. A steel mill processes bituminous coal to make coke for later use in the steel making process. Total consumption counts the quantity of coal as the original nonfuel input. Any onsite consumption of coke produced from the coal is not included in total consumption because it duplicates the coal use. If the steel mill sells and ships some of the coke to another establishment, it will show up as an input of an offsite-produced energy source in the second establishment and will be included in that establishment’s consumption data. By subtracting the Btu value of the shipments from the producing establishment, the MECS avoids the double counting of the Btu of the input coal in the first establishment with the consumed coke in the second establishment.