In the virtuous race over bragging rights for the title of greenest building, there are various shades of LEED, there's net-zero energy, and there's Energy Star, too.
But how many facilities can sink a pipe into a parking lot, tap into more than enough energy to supply year-round heating needs, and just maybe have enough left over to generate much of the site's electricity?
Welcome to Reno, Nevada, where the filigreed micro-fractures that spread out from California's San Andreas and other major faults have created a subterranean wealth of hot rocks and heated water.
These geological blessings have made it possible, right in downtown Reno, for the Peppermill Resort Spa Casino a 2.2-million-square-foot complex -- to switch off its fleet of fossil-fueled boilers as part of a $9.7-million project to switch over to geothermal heat.
The hotel is saving $2.2 million per year in natural gas purchases. "That is what you call a no-brainer," says Dean Parker, who as Peppermill's Executive Director of Facilities, has overseen the four-year project.
Peppermill's past and future sit side by side in its spotless power plant shed, a stone's throw from the main hotel. To get to the new geothermal heating unit, you have to pass by four hulking Cleaver Brook Boilers. Now barely used, the central-plant boilers once cranked out up to 100 million BTUs of heat.
But today, Parker jokes he's thinking of putting them up on eBay. Replacing all four of the garage-sized boilers is a single so-called "plate and frame" heat exchanger, made by Alfa Laval and pictured at right, no larger than a modest bathroom.
The device sandwiches together hundreds of thin, table-sized stainless steel sheets that work as a radiator, transferring heat from incoming geothermal fluids that measure 174 degrees Fahrenheit into fresh water passing through the heated plates. The fresh water is thereby warmed to 120 degrees and then stored in an armada of oversized Thermoses. Earth-heated water supplies all of the hotel's needs: 1,600 guest rooms, heating, kitchens, laundry, pools, hot tubs, spas, kitchens and more.
The heat exchanger can meet the hotel's needs and then some, pulling about 900 gallons per minute of geothermal fluids from the earth. Both it and the well are designed to crank up to 1,500 gallons per minute. "So far as we know, we're the only hotel-casino fully heated by on-site geothermal," says Parker.
Geothermal Heating is a Go; Energy is on the Horizon
Electricity generation could be the company's next project. The geothermal resource below Peppermill has enough capacity that the Peppermill is scoping out a 6- or 7-megawatt electricity generator. With commercial rates for power in the Reno area at around 9 cents per kilowatt-hour, the savings could be considerable.
Next page: Challenges to Digging for Heat