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Article # 0038
TEXAS STATE AIR QUALITY PERMITTING CONSIDERATIONS FOR CONSTRUCTION OF A SMALL BIODIESEL FUEL PLANT
by Jack L. Bullard, P.E.
The technical and economic feasibility of producing alternative and renewable fuels has been revisited over the past several years by both established fuel producers and small scale entrepreneurs. The main economic incentives have been the increased cost of traditional fuel (fuel from virgin petroleum feedstock) and tax incentives for producers of alternative and renewable fuels. The focus of this article is on the production of biodiesel fuel and the means of permitting the construction and operation of a biodiesel plant in the State of Texas. Specifically, this article covers air quality permitting of a new biodiesel plant. Common sources of emissions from a biodiesel plant are reviewed and the plants proposed construction and operation is compared to Texas air quality regulations.
Biodiesel is made through a chemical process called transesterfication whereby the glycerin is separated from the fat or vegetable oil. The process leaves behind two products: methyl esters (the chemical name for biodiesel) and glycerin; a byproduct that can be used for the production of soap, energy, or as a feedstock for other products.
In this process the vegetable oil, animal fat, or other appropriate feedstock reacts with methanol, and a catalyst in a transesterfication reaction. The reaction takes placed in closed loop process vessels where the feedstock, catalyst, and methanol are mixed thoroughly to maximize the reaction. The products of the reaction are allowed to settle in multiple horizontal closed loop process vessels. The heavy glycerin settles to the bottom and biodiesel rises to the top.
Biodiesel feedstock such as oil, grease, soybean oil, poultry fat is unloaded through the tanker truck loading rack (EPN RACK) into one or more vertical fixed-roof atmospheric feed tanks (EPN FEEDTANKS).
In addition, methanol, used to react with the feedstock to produce biodiesel, is unloaded at the truck rack (EPN RACK) into a Methanol Tank (EPN METHANOLTANK) as well as Sodium Methylate catalyst contained in 70% methanol solution is unloaded into a Catalyst Tank (EPN CATALYSTTANK). Both of these tanks will utilize internal floating roofs with mechanical seals to limit air emissions of methanol. The necessity of an Internal Floating roof for methanol is due to one or more of the following considerations:
The biodiesel feedstock is blended together in multiple Blendstock Tanks. The methanol and catalyst are introduced to the feedstock to begin the transesterfication. One or more passes of transesterfication and glycerin removal occur. The glycerin by-product is routed to an intermediate Glycerin Tank and then eventually to a larger Glycerin Storage Tank. The glycerin is the only material to be loaded out through the truck rack (EPN RACK) and is therefore the only source of emissions at EPN RACK.
The tank pads, loading rack area, and the building that house the reaction and settling vessels have pad and floor drains to collect stormwater and washdown which is routed to the Oil and Water Separator. The fugitive VOC emissions from the Oil and Water Separator and other minor process equipment such as pumps, drains, valves and non-welded connectors have been assigned EPN FUG. Water and oil from the drain collection system is routed to the Oil and Water Separator (OWS) where it is separated into oil and water phases. The oil phase will periodically be pumped to OWS Oil Tank and the water phase to process water storage tank.
EMISSIONS DATA AND CALCULATIONS
New emissions are fugitive VOCs from minor process equipment, two IFR storage tanks, multiple fixed-roof storage tanks, and a loading spot for glycerine.
Emissions for each tank were calculated per TCEQ Guidance and the latest version of EPA’s TANKS 4.09d program which incorporates EPA’s Air Pollutant Emission Factors (AP-42) and American Petroleum Institute (API) air emission methodology for storage tanks. A copy of the TANKS program is available for download and public use from the U.S. Environmental Protection Agencies (EPA) website.
The latest AP-42 emission factors for fugitives from minor process equipment (valves, pump seals, connector leaks, drains, and separator) and tanker truck loading - along with TCEQ guidance - were utilized to estimate emissions from these fugitive sources. Copies of the emission factors and guidance are available from the EPA and Texas Commission on Environmental Quality (TCEQ) websites.
STATE REGULATORY REQUIREMENTS
Each state has regulatory requirements specific to that state. All states must meet federal environmental regulatory requirements, but can create additional requirements or expand requirements as long as they are more stringent then the federal requirements and do not contradict or interfere with federal requirements. When evaluating the construction of a new emission source the permit engineer should become familiar with all local, state, and federal permitting regulatory requirements. The sections that follow list Texas state regulatory requirements in effect as of the date of this article. In some instances states may incorporate federal requirements into their state code. The Texas Administrative Code (TAC) is shown in bold below followed by an example response to the code or regulatory permitting requirement. General requirements are addressed under 30 TAC Chapter 106, Subchapter A below, followed by specific requirements under Subchapters U and K.
Texas Commission on Environmental Quality
Chapter 106 - Exemptions from Permitting
SUBCHAPTER A: GENERAL REQUIREMENTS
§106.4. Requirements for Permitting by Rule.
(a) To qualify for a permit by rule, the following general requirements must be met.
(1) Total actual emissions authorized under permit by rule from the facility shall not exceed 250 tons per year (tpy) of carbon monoxide (CO) or nitrogen oxides (NOx); or 25 tpy of volatile organic compounds (VOC) or sulfur dioxide (SO2) or inhalable particulate matter (PM10); or 25 tpy of any other air contaminant except carbon dioxide, water, nitrogen, methane, ethane, hydrogen, and oxygen.
Total actual emissions authorized under permit by rule from this facility (biodiesel plant) are much less than the emission limits of each air contaminant listed above or any other regulated air contaminant not listed. Only VOC will be emitted by the new biodiesel plant as any process heat will be provided by electrical sources and/or heat exchange. Total emissions under permit-by-rule at this site, including emissions from the proposed biodiesel plant, will not exceed 25 tons VOC per year.
(2) Any facility or group of facilities, which constitutes a new major stationary source, as defined in §116.12 of this title (relating to Nonattainment Review Definitions), or any modification which constitutes a major modification, as defined in §116.12 of this title, under the new source review requirements of the Federal Clean Air Act (FCAA), Part D (Nonattainment) as amended by the FCAA Amendments of 1990, and regulations promulgated thereunder, must meet the permitting requirements of Chapter 116, Subchapter B of this title (relating to New Source Review Permits) and cannot qualify for a permit by rule under this chapter. Persons claiming a permit by rule under this chapter should see the requirements of §116.150 of this title (relating to New Major Source or Major Modification in Ozone Nonattainment Areas) to ensure that any applicable netting requirements have been satisfied.
The new process unit will be located at ABC Fuel’s Anytown Texas site that is located in a moderate nonattainment area for ozone under the promulgated 8-hour standard codified in 30 TAC 116. The major source emission threshold for the nonattainment area is 100 tons per year site-wide and the major modification threshold is 40 tons per year (tpy) as shown in Table I of 30 TAC §116.12(11)(A). The major modification threshold is applicable only to existing major sources per footnote 2 of Table I.
The permitted site-wide maximum potential-to-emit is 10 tpy VOC and 5 tpy NOx; therefore the site is not a major source of ozone for either precursor pollutant.
This project does not constitute a major modification under current Nonattainment definitions since the increase in emissions would not cause the site to become a major source, that is, emit more than 100 tpy VOC ; therefore, Non-attainment New Source Review is not applicable to this project.
(3) Any facility or group of facilities, which constitutes a new major stationary source, as defined in 40 Code of Federal Regulations (CFR) §52.21, or any change which constitutes a major modification, as defined in 40 CFR §52.21, under the new source review requirements of the FCAA, Part C (Prevention of Significant Deterioration) as amended by the FCAA Amendments of 1990, and regulations promulgated thereunder, must meet the permitting requirements of Chapter 116, Subchapter B of this title and cannot qualify for a permit by rule under this chapter.
This facility is a minor (non-major) stationary source of all Prevention of Significant Deterioration (PSD) regulated pollutants, since the total emissions from the site after the project are less than the PSD major source emission thresholds of 100 tons per regulated pollutant.
Also, the project is a minor modification under the PSD program since the net emission increase of all regulated pollutants from this project are less than the PSD significance levels of 40 CFR §52.21.
(4) Unless at least one facility at an account has been subject to public notification and Texas Commission on Environmental Quality Page 2 Chapter 106 - Exemptions from Permitting comment as required in Chapter 116, Subchapter B or Subchapter D of this title (relating to New Source Review Permits or Permit Renewals), total actual emissions from all facilities permitted by rule at an account shall not exceed 250 tpy of CO or NOx ; or 25 tpy of VOC or SO2 or PM10 ; or 25 tpy of any other air contaminant except carbon dioxide, water, nitrogen, methane, ethane, hydrogen, and oxygen.
Total actual emissions from from all facilities permitted by rule will not exceed the limits listed above. Therefore this facility is not required to perform public notification.
(5) Construction or modification of a facility commenced on or after the effective date of a revision of this section or the effective date of a revision to a specific permit by rule in this chapter must meet the revised requirements to qualify for a permit by rule.
This facility (biodiesel plant) is being registered under the permit by rule general conditions and specific permits by rule 106.261 (to evaluate methanol and other pollutant off-property impacts and minor process equipment emissions), 106.472 (to evaluate non-methanol storage tank emissions and loading) and 106.478 (to evaluate methanol storage tank emissions) that are currently in effect. If construction is delayed or a modification to the plant is made, the version of the general conditions and permit by rule in effect at that time will be complied with.
(6) A facility shall comply with all applicable provisions of the FCAA, §111 (Federal New Source Performance Standards) and §112 (Hazardous Air Pollutants), and the new source review requirements of the FCAA, Part C and Part D and regulations promulgated thereunder.
ABC Fuels will comply with all provisions of the FCAA including Federal New Source Performance Standards. The site is a minor source of hazardous air pollutants (HAP) in that it currently emits, and after the proposed project will continue to emit, less than 10 tpy of any single HAP or 25 tpy of aggregate HAP and therefore no §112 regulations apply.
(7) There are no permits under the same commission account number that contain a condition or conditions precluding the use of a permit by rule under this chapter.
The site has no other registrations or permits with a condition precluding the use of a permit by rule under this chapter.
(8) The proposed facility or group of facilities shall obtain allowances for NOx if they are subject to Chapter 101, Subchapter H, Division 3 of this title (relating to Mass Emissions Cap and Trade Program).
The Mass Emissions Cap and Trade Program apply to all stationary facilities which emit nitrogen oxides (NOx) in the Houston/Galveston (HGA) Nonattainment. This facility is not located in the HGA area.
(b) No person shall circumvent by artificial limitations the requirements of §116.110 of this title (relating to Applicability).
The registration of this facility will not circumvent the requirements of 116.110 by artificial limitations.
(c) The emissions from the facility shall comply with all rules and regulations of the commission and with the intent of the TCAA, including protection of health and property of the public, and all emissions control equipment shall be maintained in good condition and operated properly during operation of the facility.
The facility will comply with all applicable requirements of this part and with the intent of the TCAA.
(d) Facilities permitted by rule under this chapter are not exempted from any permits or registrations required by local air pollution control agencies. Any such requirements must be in accordance with TCAA, §382.113 and any other applicable law.
The facility will comply with any requirements of local air pollution control agencies.
DISCUSSION OF SOURCE SPECIFIC PERMIT-BY-RULES
Permits by Rule 106.472, 106.478, and 106.261
Sources such as storage tanks, loading rack, and process equipment fugitives that contain or handle biodiesel feedstock, biodiesel product, or glycerine are being registered under Subchapter U, RULE §106.472 Organic and Inorganic Liquid Loading and Unloading.
The methanol internal floating roof (IFR) storage tanks construction and operation are being registered under Subchapter U, RULE §106.478 Storage Tank and Change of Service.
The minor process equipment fugitives and total methanol emissions (Methanol and Catalyst Tanks and process equipment in contact with methanol) from the biodiesel plant, in terms of health effects, are being evaluated under Subchapter K, RULE §106.261 Facilities (Emission Limitations).
TITLE 30 ENVIRONMENTAL QUALITY
CHAPTER 106 PERMITS BY RULE
SUBCHAPTER U TANKS, STORAGE, AND LOADING
RULE §106.472 Organic and Inorganic Liquid Loading and Unloading
Liquid loading or unloading equipment for railcars, tank trucks, or drums; storage containers, reservoirs, tanks; and change of service of material loaded, unloaded, or stored is permitted by rule, provided that no visible emissions result and the chemicals loaded, unloaded, or stored are limited to:
(1) the following list: asphalt, resins, soaps, lube oils, fuel oils, waxes, polymers, detergents, lube oil, additives, kerosene, wax emulsions, vegetable oils, greases, animal fats, and diesel fuels;
The construction and operation of the following storage tanks meet this section as described below:
Storage Tanks that contain oils and/or grease
Storage Tanks that will contain yellow grease an animal fat
Storage Tanks that will contain beef tallow an animal fat
Storage Tanks that will contain soybean oil a vegetable oil
Storage Tanks that will contain poultry fat an animal fat
Storage Tanks that will contain biodiesel a diesel fuel or fuel oil
Most of these tanks would also meet part (9) of this section as well as they are high boiling point materials.
(2) water or wastewater;
The following tanks are authorized under this section:
Oily Water Separator Process Water Storage Tank will contain the water fraction of the wastewater collected and separated by the oil/water separator.
Oily Water Separator Oil Storage Tank will contain the oil fraction of the wastewater collected and separated by the oil/water separator. This oil will be reused by the plant as biodiesel feedstock. This tank could meet part (1) and/or (9) of this section as well.
(3) aqueous salt solutions;
(4) aqueous caustic solutions, except ammonia solutions;
(5) inorganic acids except oleum, hydrofluoric, and hydrochloric acids;
(6) aqueous ammonia solutions if vented through a water scrubber;
(7) hydrochloric acid if vented through a water scrubber;
(8) acetic acid if vented through a water scrubber;
(9) organic liquids having an initial boiling point of 300 degrees Fahrenheit or greater. Facilities loading, unloading, or storing butyric acid, isobutyric acid, methacrylic acid, mercaptans, croton oil, 2-methyl styrene, or any other compound with an initial boiling point of 300 degrees Fahrenheit or greater listed in 40 Code of Federal Regulations 261, Appendix VIII shall be located at least 500 feet from any recreational area or residence or other structure not occupied or used solely by the owner of the facility or the owner of the property upon which the facility is located.
The following tanks are authorized under this section:
Storage Tank(s) that will contain glycerine which has an initial boiling point of 554 F.
Storage Tanks that will contain an intermediate biodiesel blend with a boiling point of 392 F or greater.
The Loading Rack (EPN RACK) will only load glycerine into tanker trucks. Glycerine’s initial boiling point is 554 F.
None of the chemicals described above are listed in the most current version of 40 Code of Federal Regulations 261, Appendix VIII Hazardous Constituents List.
Source Note: The provisions of this §106.472 adopted to be effective March 14, 1997, 22 Tex Reg 2439; amended to be effective September 4, 2000, 25 Tex Reg 8653
Texas Commission on Environmental Quality
Chapter 106 - Exemptions from Permitting
Subchapter K – General
RULE §106.261 Facilities (Emission Limitations)
Effective November 4, 2003
(a) Except as specified under subsection (b) of this section, facilities, or physical or operational changes to a facility, are permitted by rule provided that all of the following conditions of this section are satisfied.
(1) The facilities or changes shall be located at least 100 feet from any recreational area or residence or other structure not occupied or used solely by the owner or operator of the facilities or the owner of the property upon which the facilities are located.
The nearest off-property receptor that may be occupied on a regular basis is located approximately 3000 feet from any process equipment containing methanol and from the methanol tanks. This chapter is being used to authorize the minor process equipment (i.e., pumps, valves, non-welded connectors) in methanol service. The construction and operation of the methanol storage tanks will be registered under 106.478 addressed later in this report. All sources of methanol are located greater than 100 feet from the nearest off-property receptor not owned or operated by ABC Fuels as determined by satellite imagery. The area surrounding the proposed plant is industrial. There are no residential receptors, schools, or other sensitive receptors within 3000 feet of the proposed facility.
(2) Total new or increased emissions, including fugitives, shall not exceed 6.0 pounds per hour (lb/hr) and ten tons per year of the following materials: acetylene, argon, butane, crude oil, refinery petroleum fractions (except for pyrolysis naphthas and pyrolysis gasoline) containing less than ten volume percent benzene, carbon monoxide, cyclohexane, cyclohexene, cyclopentane, ethyl acetate, ethanol, ethyl ether, ethylene, fluorocarbons Numbers 11, 12, 13, 14, 21, 22, 23, 113, 114, 115, and 116, helium, isohexane, isopropyl alcohol, methyl acetylene, methyl chloroform, methyl cyclohexane, neon, nonane, oxides of nitrogen, propane, propyl alcohol, propylene, propyl ether, sulfur dioxide, alumina, calcium carbonate, calcium silicate, cellulose fiber, cement dust, emery dust, glycerin mist, gypsum, iron oxide dust, kaolin, limestone, magnesite, marble, pentaerythritol, plaster of paris, silicon, silicon carbide, starch, sucrose, zinc stearate, or zinc oxide.
Not applicable. The compounds that will be emitted (methanol) do not appear on this list. Nevertheless, total emissions of methanol from the proposed facility (biodiesel plant) are less than 6.0 lb/hr or 10.0 tpy and do not exceed the stated limits.
(3) Total new or increased emissions, including fugitives, shall not exceed 1.0 lb/hr of any chemical having a limit value (L) greater than 200 milligrams per cubic meter (mg/m3) as listed and referenced in Table 262 of §106.262 of this title (relating to Facilities (Emission and Distance Limitations)) or of any other chemical not listed or referenced in Table 262. Emissions of a chemical with a limit value of less than 200 mg/m3 are not allowed under this section.
The foot note to Table 262 of §106.262 reads, “The time weighted average (TWA) Threshold Limit Value (TLV) published by the American Conference of Governmental Industrial Hygienists (ACGIH), in its TLVs and BEIs guide (1997 Edition) shall be used for compounds not included in the table. Methanol is not listed in Table 262 but is listed in the ACGIH handbook at a TWA TLV of 262 mg/m3.
Methanol has a TLV or limit value (L) of 262 mg/m3 and as indicated above, each compound with an L value greater than 200 mg/m3 shall not be emitted at a quantity greater than 1.0 lb/hr.
Non-methanol process equipment fugitives are in contact with biodiesel, soybean oil, glycerine, and other feedstock. All of these mixtures are less toxic than methanol and therefore have a higher (indicative of being less toxic) TLV or L than methanol. Therefore the methanol L value can be used as a conservative measure and a limiting factor for evaluating the maximum allowable hourly emission rate (E) from all process equipment fugitives (both methanol and non-methanol) using L and K values from §106.262, Figure 1: 30 TAC §106.262(a)(2).
(4) For physical changes or modifications to existing facilities, there shall be no changes to or additions of any air pollution abatement equipment.
This project is not registering any change or addition to any air pollution abatement equipment.
(5) Visible emissions, except uncombined water, to the atmosphere from any point or fugitive source shall not exceed 5.0% opacity in any six-minute period.
Visible emissions, except uncombined water, to the atmosphere will not exceed 5.0% opacity in any five-minute period
(6) For emission increases of five tons per year or greater, notification must be provided using Form PI-7 within ten days following the installation or modification of the facilities. The notification shall include a description of the project, calculations, data identifying specific chemical names, limit values, and a description of pollution control equipment, if any.
A Form PI-7 is included.
(7) For emission increases of less than five tons per year, notification must be provided using either:
(A) Form PI-7 within ten days following the installation or modification of the facilities. The notification shall include a description of the project, calculations, data identifying specific chemical names, limit values, and a description of pollution control equipment, if any; or
(B) Form PI-7 by March 31 of the following year summarizing all uses of this permit by rule in the previous calendar year. This annual notification shall include a description of the project, calculations, data identifying specific chemical names, limit values, and a description of pollution control equipment, if any.
ABC Fuels is submitting a Form PI-7 and supporting documentation at this time.
(b) The following are not authorized under this section:
(1) construction of a facility authorized in another section of this chapter or for which a standard permit is in effect; and
(2) any change to any facility authorized under another section of this chapter or authorized under a standard permit.
No other sections of this chapter or a standard permit can be used to authorize the minor process equipment and their fugitive emissions.
Texas Commission on Environmental Quality
Chapter 106 - Exemptions from Permitting
Subchapter U – Tanks, Storage, and Loading
RULE §106.478 Storage Tank and Change of Service
Effective September 4, 2000
Any fixed or floating roof storage tank, or change of service in any tank, used to store chemicals or mixtures of chemicals shown in Table 478 in paragraph (8) of this section is permitted by rule, provided that all of the following conditions of this section are met:
(1) The tank shall be located at least 500 feet away from any recreational area or residence or other structure not occupied or used solely by the owner of the facility or the owner of the property upon which the facility is located.
The two methanol storage tanks will each be located > 500 feet from the nearest off-property receptor. All other biodiesel storage tanks were addressed under 106.472.
(2) The true vapor pressure of the compound to be stored shall be less than 11.0 psia at the maximum storage temperature.
True vapor pressure of methanol at its maximum storage temperature is ~ 3.0 psia.
(3) For those compounds that have a true vapor pressure greater than 0.5 psia and less than 11.0 psia at the maximum storage temperature, any storage vessel larger than 40,000 gallons capacity shall be equipped with an internal floating cover or equivalent control.
The methanol and methanol catalyst storage tanks will have capacities of 100,000 and 20,000 gallons respectively. The sodium methoxide catalyst is a solid, in a solution of 70% methanol. In solution, the air emissions from this tank will be in the form of methanol as the catalyst forms a sodium salt that is not volatile. The catalyst in methanol solution will enter the site premixed. Both storage tanks will be equipped with internal floating roofs and seals that meet the requirements of this section, the requirements of 30 TAC Chapter 115 (VOC Rule), and NSPS Subpart Kb for storage tanks.
(A) An open top tank containing an external floating roof using double seal technology shall be an approved control alternative equivalent to an internal floating cover tank, provided the primary seal consists of either a mechanical shoe seal or a liquid-mounted seal. Double seals having a vapor- mounted primary seal are an approved alternative for existing open top floating roof tanks undergoing a change of service.
Not applicable. Open top tanks will not be utilized.
(B) The floating cover or floating roof design shall incorporate sufficient flotation to conform to the requirements of American Petroleum Institute Code 650, Appendix C or an equivalent degree of flotation.
The two methanol storage tanks will meet this requirement
(4) Compounds with a true vapor pressure of 0.5 psia or less at the maximum storage temperature may be stored in a fixed roof or cone roof tank which includes a submerged fill pipe or utilizes bottom loading.
The methanol storage tanks will utilize IFRs as described in section (3) above.
(5) For fixed or cone roof tanks having no internal floating cover, all uninsulated tank exterior surfaces exposed to the sun shall be painted chalk white except where a dark color is necessary to help the tank absorb or retain heat in order to maintain the material in the tank in a liquid state.
The methanol tanks will be painted chalk white.
(6) Emissions shall be calculated by methods specified in Section 4.3 of the current edition of the United States Environmental Protection Agency Publication AP-42. This document may be obtained from the Superintendent of Documents, Washington D.C. 20402. It is Stock Number 0550000251-7, Volume I.
ABC Fuels, Inc.
The most current AP-42 emission calculation methodology was utilized to calculate storage tank emissions.
(7) Before construction begins, storage tanks of 25,000 gallons or greater capacity and located in a designated nonattainment area for ozone shall be registered with the commission's Office of Permitting, Remediation, and Registration in Austin using Form PI-7. The registration shall include a list of all tanks, calculated emissions for each carbon compound in tons per year for each tank, and a Table 7 of Form PI-2 for each different tank design.
ABC Fuels is submitting a Form PI-7 and supporting documentation for both tanks at this time.
(8) Mixtures of the chemicals listed in Table 478 which contain more than a total of 1.0% by volume of all other chemicals not listed in Table 478 are not covered by this section.
The only volatile chemical, methanol, is an approved alcohol in Table 478.
Conclusions and Considerations
Small Biodiesel Plants or process units can meet TCEQ Permit by Rule Requirements due to the low volatility (low air emission potential) and relative lack of adverse environmental impact of the biodiesel feedstock and products. One of the most important considerations in terms of air quality impact is the presence of methanol. Three important considerations to reduce the off-property impact of methanol are:
Jack L. Bullard, P.E. is an Engineering Partner of Bullard Environmental Consulting, Inc. He has over 18 years experience in environmental engineering, compliance, and permitting. Jack has a Bachelors of Science Degree in Chemical Engineering from the University of Texas at Austin.
Jack L. Bullard, P.E. No. 83547
Final Edition Completed December 20, 2007 from Previously Composed Material.
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