OXFORD – Miami University may be steeped in tradition, but its legacy of generating electricity by burning coal is one it looks forward to ending.
The school is well on its way to a coal-free future with an ambitious, multi-stage project that would heat and cool 40 percent of the Oxford campus using a geothermal system and while converting the rest of campus to natural gas.
A utility master plan approved last year calls for the elimination of coal use by 2025, a tall order for a sprawling campus that educates more than 17,000 students annually, using its own coal plant to fuel steam boilers through miles of underground piping.
The geothermal system is expected to be more than four times as efficient as the old model that uses cooling towers and steam boilers to sate the campus’s vast appetite for heating and cooling buildings and water, not only for people but for computer banks and laboratories.
“This is the coolest project I’ve ever done by far,” said Doug Hammerle, Miami’s director of energy systems who is managing construction.
New System Saves Energy -- And Eventually Money
Here’s how the geothermal system works: Engineers drill wells 600 feet deep and circulate water through them to take advantage of the nearly constant 55-degree underground temperatures. That temperate water is then heated and cooled using heat pump chillers and piped from central plants into campus facilities, where air runs over the water coils to heat or cool.
The base of temperate water that the geothermal system produces enables heat pump chillers to use far less energy than conventional systems in use today.
“The energy model has calculated over 400 percent improvement in energy efficiency over our traditional methods,” Hammerle said.
It’s not cheap.
The geothermal conversion is estimated to cost $58.5 million (including upgrades to what is now the coal-fired power plant) compared to $42.5 million to expand and maintain current heating and cooling facilities. Most campus buildings are heated by steam radiators and will need to be retrofitted with larger hot water pipes for the geothermal system. But the operating and maintenance costs will be $750,000 to $1.5 million less annually starting in 2025.
Land that covers the wells can’t be used for buildings of any significant weight. Ponds, green spaces and parking lots are all options, the first two of which can be seen as a plus by those interested in environmentally friendly attractions rather than more bricks and mortar.
In a test case, of sorts, Miami retrofitted Elliott and Stoddard halls, the two oldest and most iconic buildings on campus, with geothermal units last year, drilling 17 wells in 2011. The conversion reduced energy use by 60 percent, Hammerle said.
In a more ambitious phase now under construction, engineers have drilled 315 wells that will serve two new residence halls and a dining hall on Miami’s Western campus beginning next year. Interconnected storm-water ponds spread over 1.5 acres will cover most of the wells and will irrigate nearby Cook Field, a popular recreation area for students, as well as beautify the area. A new plant that will chill and heat water for those buildings and, eventually, others, is being constructed near the pond.
Ohio Climate Ideal for Geothermal Systems
Geothermal systems are ideal in a four-season locale like southwest Ohio, Hammerle said.
“The beauty of this area of Ohio is the balance in temperatures,” Hammerle said. In hot weather, Miami will call on the wells to cool warm water, which gradually raises the well temperatures. But before underground temperatures rise too high to lose their cooling effectiveness, the season changes, and Miami will pump cooler water into the wells to warm it for heat.
Plus, Miami requires year-round cooling of data centers and laboratories that produce a lot of heat. The geothermal operation is a closed system, meaning there is very little water or energy wasted. Instead of having cooling towers that use water to cool huge compressors, the geothermal system recaptures the water used for air conditioning and reuses the warmer water as a base for making hot water.
The move away from cooling towers alone will save 16 million gallons of water annually, Hammerle said.
Along with the conversion of the rest of campus to natural gas, the geothermal system will reduce Miami’s carbon output by 31 percent compared to 2008.
Retrofitting The Rest of Campus
While the university saw clear benefits to converting 40 percent of the campus to the geothermal model, the cost of converting the other 60 percent – mostly on the southern end of campus – would have been prohibitively expensive, at least at this point.
“The south end of campus has so many miles of infrastructure for steam piping that converting
it would be such a cost that it would be difficult to pay that back,” said Cody Powell, vice president of facilities planning and operations.
Instead, that 60 percent of campus will be converted to simultaneous heating and cooling (SHC), by still pumping steam (heated to 180 degrees) through narrow steam pipes between the power plant and buildings but then converting that steam into hot water (about 140 degrees) and running that through larger hot water pipes inside buildings.
The new system will replace the huge coal-fired boilers that produce steam with smaller natural gas-powered boilers that will deliver more precise loads of heat to buildings.
“The big pickup is converting to simultaneous heating and cooling,” Powell said. “The icing on the cake is putting in the geothermal wells which allows us to store and extract heat from the wells.”
For the foreseeable future, the electricity needed to run the chillers and boilers will be made mostly by natural gas.
Multiple Phases To Take Years
But Powell said the conversion leaves Miami with flexibility for the future. “When you convert to geothermal, your energy costs are really only electricity for pumping and running the heat pump chillers. You can buy it or you can produce it. We could go with solar, hydrogen fuel cells, coal. Whatever we want and have more control of pricing,” he said.
Additional phases are in the works:
• Starting in 2015, five residence halls and dining facilities in the East Quad will be converted to SHC at a cost of $2 million.
• Starting in 2016, buildings in the North Quad will be converted to SHC, pending financing and formal board approval, for about $2.5 million.
• In two additional phases beginning in 2017 and 2025, the rest of Western campus’s existing buildings will be converted.
Hammerle said an estimated 2,265-2,565 wells will be needed for the geothermal system when it’s complete.
Engineers will close down sections of campus in phases to retrofit buildings that are now heated using steam radiators and either have no air conditioning or conventional cooling units. Because of the expense of geothermal systems, some buildings will go through an intermediate step of being converted to shared heating and cooling.
Geothermal isn’t the only conservation innovation being employed. The ponds on the Western campus will not only collect storm-water runoff. Condensation that collects on cold-water pipes within the residence halls will be trapped and directed into the pond – an estimated 5,000 gallons a day that will be re-purposed instead of evaporating.
The new Western campus dining hall and other buildings will be topped with green roofs – instead of shingles, sedum grass will grow and insulate the building.
“This really is going to transform the way we manage our utilities, and environmentally, it’s the right thing to do,” Powell said.