Geothermal System Expo: Can You Dig It?
There was plenty to dig into at the various technical sessions.
At the opening session, a number of people identified themselves as new attendees. They and the rest of the audience received first an overview of a new geo-thermal project installed here in Stillwater.
A Geo RestaurantJim Bose, executive director of IGSHPA, introduced the keynote panel, consisting of all the interests involved in the Joseppi's restaurant job. Stan Clark of the Stan Clark Cos., and owner of Joseppi's, said that before this he knew nothing about geothermal. The job was a learning experience for him as well as most of the others.
Mike Herron of Stillwater Power noted that the utility established a new rate for the geothermal system. After the first 20,000 kWh, the rate is just a straight energy charge with a small markup. The restaurant will save about $4,000 a month based on the rate modification due to the expected energy savings.
In introducing contractor Lynn Vick of Air-O Heating & Air Conditioning, Bose stated that "He was the only one on the job who knew what to do and when to do it." Vick, who refers to his trenchers as "utility locators," said that he installed 90% horizontal loops. About 45,000 ft of pipe was buried under the drive, parking, and sidewalk areas.
Vick remarked that Clark informed him, "If it doesn't work, that's where your new shop will be."
Phil Schoen of Geo-Enterprises, which represents Florida Heat Pump, said that they had some issues regarding compaction with the horizontal application, but they corrected them.
With the different elevations, piping was a challenge, but "in the real world you have to deal with issues all the time." What works perfectly on paper isn't necessarily going to work that way in the field.
Joseppi's will see a lot of savings on maintenance, Vick stated, because the more commonly used rooftop air conditioner will suck in grease from the kitchen exhaust. So rooftop units "will start going downhill right away."
He concluded by pointing out that with all the horizontal pipe he installed, "You can't plant a tree there unless you ask me."
Rejecting HeatIn one of the following sessions, Jeffrey Spitler of Oklahoma State University spoke on hybrid systems using shallow ponds as supplemental heat rejecters.
He said that most commercial buildings reject a lot more heat than they extract. Using short-time step modeling, a pond model was developed to measure convection, thermal radiation, incident solar radiation, evaporation, and other factors.
Experimental validation was done using two ponds containing slinky coils. The actual return temperatures "pretty well matched the model return temperatures," said Spitler.
Applications in Houston, TX, and Tulsa, OK, were then studied. In Houston, the use of a pond drops the lifecycle cost of the system almost in half. In Tulsa, savings are much less using a pond, but are still significant.
Spitler's conclusions are that, for Houston and Tulsa at least, this system reduces first cost and operating cost. However, it probably wouldn't work as well further north.
He recommended that further investigation be done on optimal design procedures, since the conditions he used may not be optimal. Research should be extended to cover additional building types, climates, etc. Also, Spitler noted that economic comparisons should be expanded to include conventional systems.
Long-term InvestmentThe presentation of Phil Albertson, P.E., of Ditch Witch, was called "Geothermal: An Investment, Not an Expense." Albertson discussed a 25-year lifecycle cost analysis done by the federal government.
He noted that geothermal heat pump systems have a higher first cost than other hvac systems, but the 25-year cost is significantly lower. The break-even point compared to other systems ranged from a low of three years to a high of 13.
He then provided highlights of the Oklahoma State Capital Build-ing project. This 855-ton system consists of 0.5- to 30-ton heat pump units using horizontal and vertical loops. The system replaced 138 different hvac units and improved indoor air quality, said Albertson.
At the Park Chase apartment complex in Tulsa, loops were installed by drilling around the perimeter of the buildings. A total of 416 heat pumps are used here, replacing electric chillers and gas boilers. The energy savings estimate is 50%, or about $60,800 per year.
In a Stillwater-area project, a 3.5-ton heat pump was installed with a total cost of $6,252. The system saved $810 the first year, Albertson stated, and reduced system demand by 16 kW for the rural electric utility.
John Shonder of the Oak Ridge National Laboratory then discussed the U.S. Department of Energy's Federal Energy Management Pro-gram (FEMP). The mission of FEMP is to reduce the cost of government by reducing energy use.
Per an executive order signed by President Clinton, the federal government must reduce energy use by 35% relative to 1985 levels. Geothermal heat pump (GHP) systems have been identified as an energy-efficient technology. How-ever, "The benefits are achieved only when the technology is applied properly," said Shonder.
He added that in order for GHP systems to become mainstream, the industry needs:
- Construction cost estimating guides;
- Maintenance cost estimating guides;
- Feasibility study guides;
- Reliable software to estimate energy and cost savings;
- Guide specifications; and
- Accessible contractors who can install these systems.
FEMP has put together a core GHP team to formalize and improve the presentation of data. Accomplishments of the team to date are:
- An improved method to analyze data;
- Development of benchmarks (a calibrated model predicted energy savings within 5% of actual value);
- An interactive construction and maintenance cost database; and
- Development of guide specifications (a generic spec has been developed).
FEMP's ongoing work includes the creation of a survey guide/ auditor training, energy estimating guide, and feasibility study guide.
For more information on FEMP and its geothermal program, visit www.eren.doe.gov/femp.