A Wisconsin-based healthcare operator that already uses organic brewery wastes to fuel a CHP unit is now partnering with a landfill site to pipe waste gas for more CHP plant at a hospital. With other plans for on-site wind and geothermal energy, the aim is for total energy independence. Cliff Haefke and Corey Zarecki report.
Healthcare systems nationwide are looking for innovative ways to save on energy costs. According to the US Department of Energy (DOE), the nation’s 8000 hospitals are among the most energy-intensive commercial build-ings, with more than 2.5 times the energy intensity and carbon dioxide emissions of commercial office buildings. With US hospitals spending more than $5 billion on energy costs annually, finding solutions to these rising costs has become critically important.
One of the energy cost reducing solutions that many hospitals nationwide have turned to is combined heat and power (CHP) – the sequential production of electrical and thermal energy from a single fuel source that is located at/or near the point of use. According to the US DOE CHP database, maintained by ICF International, over 200 hospitals in the US operate CHP systems and experience the numerous benefits these technologies have to offer.
Recently, Gundersen Lutheran Health System teamed up with two organizations to implement two separate heat and power projects utilizing renewable energy fuel sources involving private and government industries.
THE JOURNEY TO ENERGY INDEPENDENCE
Gundersen Lutheran Health System (GLHS) is a physician-led, not-for-profit healthcare system that serves the tri-state region of western Wisconsin, northeastern Iowa and southeastern Minnesota. The health system is headquartered in LaCrosse, Wisconsin and employs over 6000 staff.
Today, the GLHS is taking innovative steps in how hospitals approach the concept of sustainability through their strategically planned energy conservation and efficiency measures and their implementation of clean and renewable energy projects. The health system is setting the bar high for hospitals and healthcare facilities around the nation and is proving to be an industry leader focused on reducing its dependency on fossil fuels and being environmental stewards.
Like many facilities, energy costs were increasing at an alarming rate for Gundersen Lutheran and – in turn – these costs were being passed on to patients in the form of higher health costs. In 2007, the energy costs were increasing at a rate of more than $350,000 per year (excluding campus growth). Energy reduction became top priority.
In February 2008, Gundersen Lutheran develop-ed a programme titled Envision that incorporated the healthcare system, setting a goal to reduce energy consumption by 20% by 2009, and to become 100% energy independent by 2014, by generating the equivalent or more in clean and renewable energy that the health system consumed.
‘The goal is to reduce our energy costs, which ultimately reduces costs for our patients,’ says Corey Zarecki, Gundersen’s efficiency improvement leader. To meet these goals, Gundersen Lutheran engaged in a number of energy efficiency programmes and smart business strategies, beginning with several comprehensive energy audits. These energy audits identified a number of initial measures that set the path towards their energy independence goals.
The energy efficiency programme followed a phased approach, which began with small, easily achievable steps and progressed to more elaborate plans, which required time and capital to develop. The variety of retro-commissioning and energy reducing measures that were implemented early on and yielded more than $1 million in annualized benefits included:
• Retrofitting the light fixtures in six buildings on two campuses, which realized 1.5 GWh in electricity savings and about $245,000 a year in reduced energy costs by the end of 2009.
• Air handlers in three buildings were scheduled to run only when needed. The zone scheduling led to a reduction of more than $78,000 in energy costs and saved more than 1.2 GWh per year. Paybacks were experienced immediately.
• Reprogramming cool-ing system controls, which reduced energy consumption by about 1.1 GWh a year. The chiller/tower optimization led to annual savings of approximately $65,000 by the end of 2009.
• Changes to the way Gundersen Lutheran’s boilers were used led to a cost savings of nearly $64,000 annually and energy savings of about 2170 MWh by the end of 2009.
• Automatic computer shutdown software led to electric energy savings of 645 MWh a year by the end of 2010, for an annual energy cost reduction of $40,000.
Figure 1 shows Gundersen Lutheran’s plotted road to 100% energy independence, with energy projects and their estimated implementation dates.
|Figure 1. Gundersen Lutheran’s road to 100% energy independence. Gundersen Lutheran has been implementing a number of projects to meet 100% of its energy needs for its facilities by 2014. The projects create clean and renewable energy and improve energy efficiency.|
FIRST CLEAN ENERGY PROJECT – TEAMING WITH PRIVATE INDUSTRY
The first of several clean and renewable energy projects began operation in October 2009. GLHS and City Brewery, also located in La Crosse, Wisconsin, partnered on an innovative CHP project fuelled by biogas from the brewery’s waste treatment process.
The 633 kW CHP system would generate approximately 2 GWh per year of electricity, equivalent to 5% of the electricity used on Gundersen Lutheran’s La Crosse and Onalaska campuses. The waste heat from the CHP system, estimated at approximately 3200 MWh per year, is recovered and used to heat the anaerobic digesters that produce the brewery’s biogas. According to the US Environmental Protection Agency (EPA) CHP Partnership, the energy production is equivalent to planting 306 acres of forest or removing 275 cars from the road.
City Brewery is a contract beverage producer with two production facilities located in La Crosse, Wisconsin and Latrobe, Pennsylvania. The La Crosse facility, once a historical brewery, is now a facility capable of manufacturing and packaging beers, teas, soft drinks, energy drinks and other new age beverages. The facility is capable of annually brewing over 7 million barrels and packaging over 50 million cases, making it one of the largest beverage producers in the US. Today, the La Crosse facility produces and packages a variety of beverage products including Arizona Ice Tea, Mike’s Hard Lemonade, Smirnoff Ice, and Samuel Adams.
Soon after Gundersen Lutheran established its Envision programme in February 2008, one of Gundersen Lutheran’s employees took notice of the local brewery flaring 100% of its generated biogas. The brewery was located less than a mile from the hospital; could there be an opportunity for the hospital to generate electricity using this renewable fuel resource?
The brewery produced a daily average of 3660 m3 of high strength wastewater. But as a contract brewer, its production levels and wastewater volume and composition varied considerably. To reduce the wastewater strength prior to discharging to the public wastewater treatment plant, the brewery utilized an upflow anaerobic sludge blanket (UASB) digester system that was originally installed in 1982 – which would also generate biogas. The varying levels of volume and composition of the wastewater would have significant impacts on the biogas production, creating challenges to understanding how to handle and condition the gas prior to utilization.
In the 1980s, well before City Brewery purchased the brewery in 2001, the brewery used biogas to fuel its existing boilers. As soon as the brewery staff noticed some corrosion in the boilers due to the high sulphur content found in the biogas, the staff discontinued using the biogas in the boilers and switched to flaring the biogas. So, 25 years later when the Gundersen Lutheran and City Brewery project team members would renew the interest to utilize the biogas, but now in a CHP system, the team was well aware of the potential biogas conditioning issues, most likely due to the high sulphur content in the wastewater streams that forms hydrogen sulphide (H2S) in the biogas.
With a methane content of 60 to 65%, the digesters generated on average 4.8 m3 per minute. Initial testing and sampling for biogas impurities showed an expectant range for H2S content, but later testing revealed much higher levels of H2S. To understand the variations, numerous samples were analyzed over a several month period with H2S levels registering between 2600 and 19,700 parts per million by volume.
‘It turned out that we had much higher levels of hydrogen sulphide than we originally anticipated. We also wanted to see if there was something in the brewing process that was unintentionally creating the fluctuations,’ Zarecki explained. Zarecki and his staff discovered 10 different sulphur sources, leading to the higher H2S levels, a situation not uncommon at brewery and beverage facilities producing multiple products. The sources for the higher H2S levels included, but were not limited to, chemical reactions and substances used to adjust product pH and to clean equipment. The project team investigated several biogas conditioning systems and concepts to remove the higher H2S levels.
Gundersen Lutheran’s CHP system at City Brewery incorporates a single 633 kW reciprocating engine that consumes approximately 40% of the available biogas production (i.e. baseload biogas production). Gund-ersen Lutheran and City Brewing are still investigating options to use the remaining biogas that is being flared.
|City Brewery’s UASB digester and biogas flares (prior to CHP installation)|
The generated electricity is exported to the grid, and Xcel Energy sends Gundersen Lutheran a cheque for the generated electricity under Xcel Energy’s Parallel Generation Energy Service Purchase tariff (i.e. on-peak rate of 9.86¢ per kWh and off-peak rate of 3.85¢ per kWh).
The recovered heat from the engine generator and exhaust system is captured and utilized to heat the digesters, boosting the biogas production levels in the winter months. Once the CHP system was operational, City Brewery was able to remove its ageing boiler and avoid the purchase of a new boiler. The treated wastewater is sent on to the city wastewater treatment facility and the removed solids are used as soil amendments and/or sent to a landfill.
This project did contain its challenges. It took a while to get the system up and fully operational, largely due to the high and variable concentration of H2S in the biogas. Zarecki points out: ‘a key lesson we learned is that when forming renewable energy partnerships, make sure it is structured so that it is a win-win for everyone involved. Second, you have to have clear and constant communications, especially in the beginning of the project. Good communications have led to a better understanding of partnership opportunities.’
SECOND PROJECT – TEAMING UP WITH A GOVERNMENT ENTITY
Today, nearly 400 landfill gas-to-energy projects in the United States are generating electricity. However, less than 7% of these projects capture and utilize the waste heat generated by the prime mover to offset existing facility thermal loads – that is, through incorporating CHP concepts and technologies.
One of the main factors contributing to the low number of landfill gas fuelled CHP installations is that landfill sites do not require space and/or process heating needs. Therefore, the opportunity to utilize the recovered heat with the increased efficiency gains is a missed opportunity with many landfill gas fired projects.
Those landfill gas-to-energy projects that do incorporate CHP are typically those in which the landfill gas is piped off-site to neighbouring or nearby facilities where both the generated electricity and thermal energy can be used off-site.
Gundersen Lutheran continued to understand the value of teaming with other organizations to achieve its energy goals and further demonstrate its environmental stewardship as it embarked on a renewable fuelled landfill gas-fired renewable energy project. The healthcare system entered into a project with La Crosse County, where landfill gas would be piped from the county landfill to one of Gundersen Lutheran’s healthcare campuses.
When Gundersen Lutheran first began exploring the potential for a landfill gas-to-energy project with the county, early results indicated a stand-alone engine generator unit would provide the least expensive option. The engine unit would be installed on the landfill site with no heat recovery. Although the electric generating project would be economically feasible, Gundersen Lutheran realized a greater opportunity existed if the available heat from the engine generator unit could be captured and utilized to supplement existing thermal loads and thereby offset the associated fuel consumption.
|Container cover to Gundersen Lutheran’s CHP system installed at City Brewery|
This concept would not be feasible on-site at the landfill, but an opportunity existed to pipe the landfill gas approximately two miles away to Gundersen Lutheran’s Onalaska healthcare campus located in Onalaska, Wisconsin. Gundersen Lutheran wanted to explore this opportunity further as this energy recovery concept was more in line with Gundersen Lutheran’s overarching energy goals than simply generating electricity on-site at the landfill site.
Gundersen Lutheran turned to the US DOE Midwest Clean Energy Application Center (Midwest RAC) for assistance in investigating the heat recovery opportunities at the Onalaska healthcare campus utilizing landfill gas in an engine generator unit. The Midwest RAC, located at the University of Illinois at Chicago, is one of eight regional application centers sponsored by the US Department of Energy that promotes and facilitates the implementation of clean energy technologies of CHP, waste heat recovery, and district energy.
Analysis showed the landfill site produced 510 m3/hr of landfill gas with the potential to generate 1.1 MW of electricity. The Midwest RAC identified that the heat recovered from an engine generator’s exhaust and jacket water systems could supply a significant quantity of the required space heating and domestic hot water needs at two of the campus buildings.
In September 2010, Gundersen Lutheran selected a turnkey engineering firm to design and build the landfill gas renewable energy project at the Onalaska campus. Construction of the project will begin in the summer of 2011 and is expected to be completed by the end of 2011. Through the health system and the county teaming up on this project, it’s estimated that the landfill will collect approximately $300,000 a year from selling the landfill gas to Gundersen Lutheran, while Gundersen Lutheran anticipates generating $800,000 a year in revenue from selling the electricity to Xcel Energy and in addition realizing thermal energy savings from the recovered heat and avoided boiler fuel consumption.
Once operational, the landfill gas-fuelled power and thermal generation projects are expected to offset approximately 12% of Gundersen Lutheran’s total energy use.
‘This is a great use of a currently unused natural resource and it is an excellent example of what a public-private partnership can achieve in our community. We considered many partners for this project, and Gundersen Lutheran was a logical fit with its experience in renewable energy projects,’ says Hank Koch, solid waste director, La Crosse County.
These are exciting times for the Gundersen Lutheran Health System as it continues on its path to energy independence. With the completion of these projects, it will have achieved approximately 40% of its energy independence goals and is still targeting 100% by 2014. Zarecki hopes these unique partnerships will inspire other organizations to explore similar ventures. ‘At this point in our nation there are three main issues that are affecting all of us, the economy, healthcare and energy. These projects, and others like it, hit on all three. We not only want to lead but teach others and make a difference.’
Cliff Haefke is with the Energy Resources Center of the University of Illinois at Chicago, and is the Associate Director for the US DOE Midwest Clean Energy Application Center. Email: firstname.lastname@example.org www.midwestcleanenergy.org
Corey Zarecki is a chemical engineer for the Gundersen Lutheran Health System and is one of the health system’s energy efficiency programme managers.
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