From:	"Long,	Michael	E"	<Michael.Long@CliffsNR.com>	

To:	Steven	Rosenthal/R5/USEPA/US@EPA,		

Cc:	"McWilliams,	Douglas	A."	<DMcWilliams@ssd.com>	

Date:	01/07/2013	10:24	AM	

Subject:	Cliffs	Natural	Resources	‐	Regional	Haze	BART	language	

Steve, 

 

Below is additional information you requested regarding managing sulfur inputs to the UTAC indurating 

furnaces. 

 

In addition, we are seeking clarification about the applicability of the natural gas/SO2 limits during natural 

gas curtailment episodes. 

 

Fuel Sulfur Operating Limit

Per our discussion the other day, Cliffs is opposed to setting a redundant operating limit to restrict SO2 

emissions. Establishing a “secondary operating limit” to restrict sulfur from UTACs solid fuel input is 

unnecessary because compliance with the UTAC BART SO2 emission limit will be determined through use 

of SO2 continuous emission monitors (CEMs). Furthermore, UTAC is balancing multiple permit and rule 

obligations that complicate our compliance strategy. A fuel restriction interferes with optimal fuel balancing 

without providing any environmental benefit. Finally, the BART SO2 determination and emission limits for 

UTAC should be consistent with the FIP BART compliance demonstration requirements for the other solid 

fuel consumers such as Keetac and Minntac. If EPA is not imposing a secondary operating limit to restrict 

fuel sulfur content at the other indurating furnaces, then UTAC should receive equal treatment. If EPA is 

moving forward with a secondary fuel sulfur limit for all, then UTAC is proposing the following: 

 

Proposal for Fuel Sulfur Input Values

Should EPA decide a secondary operating limit is necessary at UTAC to limit the sulfur content of 

the fuels, Cliffs is proposing to set the total (cumulative) fuel sulfur limit at UTAC considering all 

fuel inputs (currently coal and natural gas) as follows: 

 

a) When Line 1 and Line 2 are operating: Annual average of 0.9 lb S / mmbtu as fuel 

sulfur input. 

 

This limit is based on: [529 lb SO2/hr] * [32 lb S / 64 lb SO2] / [410 mmBtu/hr] / [100%-

25% control efficiency] = 0.9 lb S/mmbtu (before existing scrubber controls) 

 

b) During single line operation: 30-day average of 1.5 lb S / mmbtu as fuel sulfur input.

 

This limit is based on: [529 lb SO2/hr] * [32 lb S / 64 lb SO2] / [230 mmBtu/hr] / [100%-

25% control efficiency] = 1.5 lb S/mmbtu (before existing scrubber controls) 

 

Note: These values are direct conversions of the 529 lb/hr SO2 emissions rate to fuel sulfur 

input considering a conservative estimate of 25% SO2 control efficiency in the wet scrubber. 

 

 

Fuel Sampling Method

Fuel sulfur determination to demonstrate compliance will be performed pursuant to GPP permit 

condition on page A-51 (line 1) and the same language on A-58 (line 2) for coal (see attached 

excerpt from GPP Permit #13700113-005) and use of pipeline sulfur data for natural gas. 
 

Tilden Natural Gas Curtailment

In an effort to clarify the applicability of the Tilden Line 1 natural gas/SO2 limits during natural gas 

curtailment periods, we are requesting EPA to insert language into the preamble/promulgated rule to 

provide a means to temporarily use back-up fuel (currently coal) during natural gas curtailment periods. 

 Tilden Line 1 has dual fuel capability (natural gas and coal), which mitigates operational downtime risk 

during supplier induced fuel curtailment periods. If the FIP BART SO2 limit will be set based on 100% 

natural gas, Cliffs is requesting language in the FIP which will allow temporary use of “back-up” fuel 

(currently coal) during natural gas supply interruptions due to force majeure events. This request is 

consistent with other back-up fuel provisions in the FIP for furnaces which use natural gas as the “primary 

fuel” (e.g., The FIP states “These limits do not apply when the subject emissions unit is burning fuel oil”). 

 

Proposed Clarification to the preamble and promulgated FIP:

Wherever the Tilden Line 1 natural gas/SO2 limits appears in the FIP, Cliffs requests the following 

language to be inserted: “This limit does not apply when the subject unit is burning its back up 

fuel source.”

 

We appreciate your consideration of this information and do not hesitate to call me at 216-694-7359 should 

you have any questions regarding this information. 

Respectfully,

 

MICHAEL E. LONG

Director – Corporate Environmental Strategy and Programs

P 216.694.7359 (O) 216-262-8797 (M) Michael.Long@cliffsnr.com

CLIFFS NATURAL RESOURCES

200 Public Square, Suite 3300, Cleveland, OH 44114-2544 

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(See attached file: United Taconite GPP Permit Term_Coal.Sampling.docx)