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Methane CoGen System - District Energy at LOTT Building

Case Study by Jessica Schwab, Cody Fritz, Alicia Jolley and Allyce Miller
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Methane CoGen System - District Energy at LOTT Building
Renewables - Biomass
Energy generation
City of Olympia
Tom Hill, Code Official, City Planning
Trane, HDR


All of Thurston County, Tumwater, Olympia, and Lacey's wastewater is cycled through the LOTT alliance. Methane is a natural bi-product of the entire water treatment process. This methane needs to be either used or disposed of, most companies doing the latter. The LOTT Alliance chose to recycle this methane using an innovative technology, the Co-Generation System that turns the methane into electricity.  To permit this system, it first had to meet several key requirements.

Permitting Process

One of the most important key success elements of the project was for the team of engineers to prove to Puget Sound Energy that the project was worthy.  There was a lot of work.   This was done in with plan and data review assistance, energy calculations, and funding support from Puget Sound Energy.  A grant was secured from the PSE that would end up covering an impressive 70% of total costs for the project.

Due to the original 1984 Co-Gen system LOTT was already familiar with the permitting process for this type of project.  However several permits required by the Department of Ecology required extra steps for approval, as did several Codes from the City of Olympia Building Code, and a stipulation enforced by PSE.

Project Description

The Budd Inlet Treatment plant is located on a 14-acre site in downtown Olympia. The original plant has been in operation since the early 1950's. Since then the plant has undergone many expansions and up-grades in order to accommodate an increasing level of treatment and an increasing load. The LOTT Alliance is a LEED Certified building and is an organization dedicated to serving their community as efficiently and equitably as possible, while maintaining an excellent example about how to build with responsible resource management, an essential of green design. This is well aligned with their completion of the Methane Co-generation system in 2009.

The production of electricity heats water that circulates the buildings to provide hydronic heating and cooling. Not only does this co-gen system provide enough energy to meet their entire facilities heating needs, they also provide a large portion of heat to the new Hands-On Children's Museum, located across the street. In 2009 the LOTT Alliance completed the upgrade to their co-generation system. Initially they had two 4.3 MMBtu digester gas water boilers that were the basis for the first Co-generation system that lasted from 1984 to 1999. It malfunctioned because the tank that stored the methane began to corrode.

The CoGen system captures the methane bi-product, mainly from tanks called “Digesters” but throughout the entire wastewater treatment process. The gas is then transferred it to a cleaning station that “scrubs” it of any remaining non-methane components, which could harm the engine. Then the methane is sent to the 335kW GE Jennbacher generator that burns it for fuel. The engine is a very efficient turbo straight 8 cylinder model, and the attached generator is sized at 335 KW, which is the perfect combination to burn 5,000 cubic feet per hour, which is the gas rate produced in our solids digesters.  The engine produces electricity while a heat recovery system transfers it to the water running though the Digester water Loop and the Building Thermal Loop thus providing in-door heating. From the beginning this project was planned to supplement the heating load of the Hands-On Children's museum, now newly opened, across the street.   LOTT sends the museum hot water which they use in their own ventilation (HVAC) units, so only the heat source is provided.

One of the 4.3MMBtu water boilers was kept on site in the generation room for emergency back-up purposes. Also LOTT has not eliminated the flaring of excess methane. However, due to the corrosive nature of Methane, it is very costly to store.  The cost of a large storage tank is in excess of $1 million and also requires a compressor to increase the pressure.  An increase in methane-originated energy should be realized at all levels. The difficulty connecting to the grid that LOTT had and the extra steps they had to take reveal that even large-scale alternative energy production may be more ideally administered through more localized power production facilities.

To implement this project, a notice of construction (Air Permit) approval was required by the Olympic Regional Clean Air Agency (ORCAA). Also required was a DNS, Determination of Non-Significance. In order for LOTT to connect their system their system to the grid.

Design / Build Process

The new system was created due to a Washington state program entitled Energy Performance Contracting. This program connected LOTT with the company Trane who specialize in this type of green design/energy technology. This company worked with LOTT throughout the entire process along with the State of Washington Energy Department extensively in order to plan the project. They worked together for a period of several years to put together the plans and contract the construction.

Cost / Benefit

The upgrade functioned fundamentally the same as the original but used more efficient technology. One of the old boilers was kept for back-up purposes, but the heart of the system is now comprised of one 335kW Generator (GE Yenbacer) and two 1.5 MMBth natural gas boiler (along with the Aerator Turbine.) This all combines to meet the heating needs of not only the digester facility but also serves the human components, by providing heating to the two other LOTT buildings, the Administrative and Education Center, and the Water Quality laboratory. The system produces electricity that covers around 10% of the entire facilities yearly electric bill. This works out to be about $120,000 per year.

Approval Requirements

The methane co-gen project had to adhere to all the standing codes, however there are no code sections that specifically deal with methane co-gen systems. There are however, codes that define air quality and greenhouse gas emissions, which apply to this project.

All of the standard codes and permits had to be obtained for this project including the IMC, UPC, NEC, IBC

“Problem Codes” Determination of Non-significance under WAC 197-11-340(2).

This allowed them to by-pass obtaining an EIS (environmental Impact Statement) Though they did have to complete an Environmental Checklist approved by the Department of Ecology. This check list analyzed the future impact of the proposed methane Co-Generation project up-grade and determined no significant negative environmental effects. After all using the methane to power the generators does in effect reduce air pollution.

*It reduces air pollution by burning the methane by-product as fuel to create electricity, instead of simply flaring the gas off to dispose of it that way. Even so every new construction project of this caliber that is involved with the emissions of greenhouse gases (in this case CO2, methane) must comply the provisions of the Clean Air Act and obtain an ORCAA permit.

RCW  Section/Title 70.94- 70.94.151

This Washington law outlines the requirements of the Clean Air Act adopted in 1968 . This is also the law that established ORCAA =Olympia Regional Clean Air Agency. This is the organizations that requires facilities like the LOTT Alliance which emit a higher amount of greenhouse gas than most buildings, to get an ORCAA permit before construction can begin. The ORCAA permit requires LOTT to test their emissions yearly, to ensure that the they do not surpass a certain amount of CO2, H2S, and siloxide, (methane ?) emissions.

nternational Building Code Chapter 27 Section 7

Emergency and Stand-by Power Systems

When LOTT asked to be hooked up to the grid PSE required that they meet this stipulation that would protect the rest of the power grid from receiving a power surge from the generators at LOTT if there where to be a large-scale grid failure. This code requires that LOTT have what is basically a massive breaker to stop electricity created by the generator from transferring into the grid if some type of massive failure was to happen in the Puget Sound Energy system at large.

Olympia Municipal Code Chapter 8.32 NOISE

This code applies to the sound ordinances that the LOTT facility to had to adhere to the stipulation listed there in. They had little trouble meeting the requirements, but it was a concern for the community.


12 months of electrical generation data from the Co-Gen Jennbacher generator:

July, 2011: 72.2% used in cogen, 5% reused in boiler, 22.8% flared. 221,405 kWh, $15,941.00 – 29 days

Aug, 2011: 39% used in cogen, 26.6% reused in boiler, 34.4% flared. 113,843 kWh, $8,200.00 – 17 days

Sept, 2011: 70% used in cogen, 11% reused in boiler, 19% flared. 186,176 kWh, $13,404.70 – 24 days

Oct, 2011: 81% used in cogen, 0% reused in boiler, 19% flared. 316,138 kWh, $22,762.00 – 31 days

Nov, 2011: 81% used in cogen, 0% reused in boiler, 19% flared. 238,027 kWh, $17,137.94 – 30 days

Dec, 2011: 68% used in cogen, 0% reused in boiler, 32% flared. 225,721 kWh, $16,251.91 – 31 days

Jan, 2012: 74% used in cogen, 0% reused in boiler, 26% flared. 225,054 kWh, $16,204.00 – 31 days

Feb, 2012: 63% used in cogen, 0% reused in boiler, 37% flared. 201,939 kWh, $14,539.00 – 25 days

Mar, 2012: 70% used in cogen, 3% reused in boiler, 27% flared. 225,054 kWh, $16,204.00 – 29 days

April, 2012: 70% used in cogen, 18% reused in boiler, 12% flared. 225,054 kWh, $16,204.00 – 30 days

May, 2012: 83% used in cogen, 3% reused in boiler, 14% flared. 243,454 kWh, $17,285.00 – 29 days

June, 2012: 92% used in cogen, 4% reused in boiler, 4% flared. 237,754 kWh, $16,881.00 – 29 days

July, 2012: 71.5% used in cogen, 3.2% reused in boiler, 25.3% flared. 189,136 kWh, $13,429.00 – 27 days

Aug, 2012: 72% used in cogen, 3% reused in boiler, 25% flared. 134,395 kWh, $9,542.00 – 27 days

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