Waste to Energy Conversion Technologies Going Mobile An

Waste to Energy/ Conversion Technologies Going Mobile – An Introduction to RNG

CEG RNG project Technology Development History • December 2010 Cornerstone/Tetra Tech engineers developed and installed our first Bio. CNG unit at a Wisconsin landfill. • Today Tetra Tech has 14 units around the country and growing similar operating projects that have won EPA and International awards. • We hold a patent for the Bio. CNG skid, which is manufactured by Unison solutions in Iowa. • From our work with Bio. CNG, we have continued to grow our knowledge in biogas to RNG upgrading. 2

What is Bio. CNG? • Bio. CNG™ is a vehicle fuel for a green future, was developed by Cornerstone, a Tetra Tech Company. • Bio. CNG™ was invented in response to the growing interest in lower cost alternative vehicle fuels and offers a complete system for converting biogas into RNG suitable for use as vehicle fuel. • Bio. CNG™ systems uses a patented biogas conditioning system • Bio. CNG™ easily adapts to smaller-scale biogas-to-CNG alternative vehicle fuel projects. • The primary Bio. CNG™ components include: Treatment to remove H 2 S, VOCs, siloxanes and CO 2; filters to remove particulates; and chillers to reduce moisture. 3

Why RNG Continues to Grow • Biogas to electric formerly had various incentives to foster the development of these projects • With solar and wind development, utilities started to have a large portfolio of renewable electric power • Incentives for electric were not renewed • To aid in driving US consumers toward cleaner fuels, incentives to utilize cleaner fuels developed • Ethanol, and biogas to RNG or electric, incentivized on federal level (RINS), and within several states (LCFS) • Price of credits tends to fluctuate, but remains at levels that many projects can provide near term positive returns • For some, biogas management was an expense, now it can be a source of revenue 4

Biogas Sources • Landfill gas ▪ Methane 45 -60%, Oxygen 0 -2%, Nitrogen low-8%, Carbon dioxide 3550% ▪ Silica up to 2, 000 ppb ▪ Volatile organic compounds up to 2, 000 ppm ▪ Hydrogen sulfide low-500 ppm • WWTP digester gas ▪ Methane 55 -65%, Oxygen 0 -low%, Nitrogen low-2%, Carbon dioxide 35 -45% ▪ Silica low to 200 ppb ▪ Volatile organic compounds up to 2, 000 ppm ▪ Hydrogen sulfide low-3, 000 ppm • Food waste or other anaerobic digester ▪ ▪ ▪ Methane 45 -70%, Oxygen 0 -low%, Nitrogen low-2%, Carbon dioxide 30 -45% Silica low to 200 ppb Volatile organic compounds up to 2, 000++ ppm Hydrogen sulfide low-3, 000 ppm • Manure or dairy digester or other 5

General Definitions Btu – British Thermal Units CFM – Cubic Feet per Minute CNG – Compressed Natural Gas DGE – Diesel Gallon Equivalent (currently 6. 06 lbs of LNG) GGE – Gasoline Gallon Equivalents (currently 5. 66 lbs of CNG) LNG – Liquified Natural Gas LCFS – Low Carbon Fuel Standard MMBtu – 1, 000 Btu N or ND – None or None Detected RIN – Renewable Identification Numbers WWTP – Wastewater Treatment Plant 6

Bio. CNG™ Standard System Information Bio. CNG™ System Biogas Inlet Flow Bio. CNG 50 trucks/d 50 SCFM Fuel Production Small Truck Fleet 200 -300 GGE/day Large Truck Fleet 20 -27 trucks/day 2 -4 Bio. CNG 100 SCFM 375 -600 GGE/day 38 -55 trucks/day 5 -8 trucks/day Bio. CNG 200 SCFM 775 -1200 GGE/day 77 -110 trucks/day 11 -17 trucks/day Bio. CNG 400 SCFM 1500 -2400 GGE/day 150 -240 trucks/day 21 -34 trucks/day 7

RNG Credits Per DGE • 200 cfm = 800 DGE per day • 800 * $6. 06 = $4, 848 per day • 300 of 365 days a year = $1, 454, 400 per year • Bio. CNG 200 scfm Skid costs about $800, 000, operational costs of $300, 000 per year • So why are RNG projects popular, Duh! I can’t figure it out? 8

Renewable Portofolio Standards • North Carolina – 12% by 2021 (NC Gen. Statutes 62 -133. 8) • South Carolina – 2% by 2021 (HB 1189) • Virginia – 15% by 2025 (VA Code 56585. 2) • Tennessee - none 9

Types of Projects – Consumers • Direct to vehicles – must meet current CNG engine manufacturer’s specifications for their engines ▪ Methane 92%, Oxygen 0%, Nitrogen low-8%, Carbon dioxide low 1% ▪ Silica ND ▪ Hydrogen sulfide ND ▪ Dry and particulate free • Private pipeline – either a pipeline we put in, or other conveyance pipeline, not subject to utility pipeline standards required of utilities, who CNG could end up in a household stove ▪ Somewhere between vehicle specification and pipeline specification • Utility pipeline – pipeline that delivers CNG to homes, typically has more stringent standards for introducing RNG, varies widely utility to utility across the country ▪ Methane 95% to 99%, Oxygen 0%, Nitrogen 0 -1%, Carbon dioxide low ▪ Silica ND ▪ Hydrogen sulfide ND ▪ Dry and particulate free 10

Removal of H 2 S • Usually done first, can be done on wet saturated biogas. • Completed with vessel with media, low H 2 S, or biological system, high H 2 S loading. • Low cost, vessel with media, assume H 2 S levels are under 1 to 3 K ppm • H 2 S molecules stick to media. • Once media is consumed, removal, new media utilized. • Different medias and more being developed to increase media life. • For high H 2 S levels, biological process can be used. • Much more capital and challenging to operate. • Lower life cycle costs at higher H 2 S levels. 11

Removal of VOCs and Siloxanes • Usually done after H 2 S and water removal, to avoid these items taking up space on media to remove VOCs and Si. • Usually done with media, low VOC and Si loading, regenerative systems for high loading. • Vessels with media, media types based on speciated compounds of VOCs and Si. • Molecules stick to media, once media is consumed, removal, new media utilized. • Higher loading, regenerative systems used, high capital costs, lower life cycle costs. • Molecules stick to media. • Once media full, alternate vessel with fresh media goes into service. • Used media is back flushed with hot air to get molecules on media to go into air stream. • Air stream goes to a thermal oxidizer or other to destroy VOCs and Si. 12

Removal of CO 2 • Usually done last, other items will block membrane pores. • Biogas passed over membranes, pores in membranes only allow certain molecules to pass through, based on molecule size. • Methane passes through, leading to a nearly pure methane stream, product gas. • Some methane does not get through in time, and thus, remains behind with the CO 2. • CO 2 and the little bit of methane, are waste gas. 13

Removal of Moisture and Particulates • Compress and cool the biogas. • Cooling below the dewpoint, leads to water condensing and falling out of the biogas stream. • Filter then removes water and particulates within the biogas. 14

Bio. CNG Implementation Details • H 2 S, compression, cooling, VOC and Si removal, membranes. • Low capital, low O&M, if media replacement is not too often • No N 2 and O 2 removal ▪ Good at WWTP and food waste digesters, landfills need to be reviewed. ▪ Landfills underpulled, or use select wells. • Single and dual pass membranes ▪ ▪ Single 67% efficient, 25 -30 CH 4 in waste gas Dual 90% efficient, 5 -10 CH 4 in waste gas Function of incoming CH 4 and other gasses Consider value of the incoming gas, and what will be done with waste gas 15

Direct to Vehicle: Case Studies 16

1. Persigo, Grand Junction, CO

1. Persigo, Grand Junction, CO • Small scale fuel process • CNG vehicles • WWTP integration • 500 GGE • 6 -mile pipeline • Design/construction includes option to use Bio. CNG for the WWTP • Pipeline route – RR track, stream channel, wetlands, highways, existing and new easements Currently fuels: • Buses • Refuse trucks • Street sweepers • Utility pick-ups 18

2. Las Gallinas Valley, CA 19

2. Las Gallinas Valley, CA 20

2. Las Gallinas Valley, CA • Bio. CNG 100 conditioning system • Power generation for the facility • Processes 83 SCFM of WWTP biogas or 500 GGE per day • RNG for fuel stations • Designed to recover 100% of the WWTP biogas, treat onsite • Affluent Community • Heat source for digestor sludge • Included preparation and receipt of approximately $1 M grant 21

2. Las Gallinas Valley, CA 22

3. St Landry Parish, LA 23

3. St Landry Parish, LA • Original system produced 230 GGE/day fueling 15 vehicles • LFG at 50% CH 4 • Expanded system produces 640 GGE/day • Vehicles include those at the sheriff dept and a landfill contracted hauler • Franchise hauler incentivized to convert to CNG • Some of the RNG is transported to an offsite fueling location • Cleaner burning fuel • Cheaper than Diesel fuel 24

3. St Landry Parish, LA 25

RNG Delivery • Need to get RNG to vehicles • Options • Bring vehicles to RNG, put hauling yard at landfill or near WWTP • Bring RNG to vehicles • Inject the RNG into a utility pipeline • Build dedicated RNG pipe to existing CNG station, or new CNG station • Virtual pipeline, put RNG into on road tube trailers, drive and deliver RNG at existing or new CNG stations or pipeline injection point • Inject into pipeline • Once injected, can largely take it out anywhere • Need to understand the pressure, flow, and composition requirements of the pipeline, never the same, some much more stringent than others • Cost to complete injection and monitoring, to assure composition requirements met, can be costly and challenging 26

RNG is at the Vehicle, now what? • Time and Fast Fill CNG Stations • CNG is compressed to nearly 3, 600 psi in trucks • Time fill ▪ Has a number of trucks connected to a hose that is connected to the compressor ▪ Compressor compresses gas up to 3, 600 psi, and fills the trucks directly ▪ One truck at a time, or all together ▪ Relatively low cost • Time fill issues ▪ What happens during the day when all the trucks are out driving around, where does RNG getting produced 24 hours a day go ▪ Typically requires some storage for when trucks are out 27

CNG Stations • Fast fill ▪ Common gas station pump with hose ▪ Has multiple tanks of gas stored at high pressure ▪ Upon connection, high pressure tanks allow CNG to quickly flow into vehicle. First tank gets truck tank to a high pressure, but then pressures equalize, then next storage tank takes over, and again for third, allowing truck to be filled. ▪ Can occur quickly if sufficient high pressure storage tanks, and compressor that can then start to fill them again ▪ Much higher cost, high pressure storage tanks • Fast fill issues ▪ Costs of capital and O&M ▪ What happens during the day when all the trucks are out driving around, where does RNG getting produced 24 hours a day go ▪ Typically requires some low pressure storage in addition to the high pressure storage 28

Other Fueling Station Considerations • Need to match RNG production and storage with vehicles and fuel demand • How many vehicles, growth pattern • How much fuel use per truck, per day • Does vehicle fuel use change on weekends, stop? • High and low pressure storage • Low, around 200 psi, 350 DGE, high upwards of 3, 000 psi, 2, 500 DGE • Low requires more tanks and capital cost; costs to compress the gas is lower • High requires fewer tanks and less capital costs; slightly higher cost to compress into the tank; and requires decanting to keep the gas from freezing when released 29

Comments and Questions 30