WASHINGTON, DC, USA, August 22, 2007.
The use of geothermal heat pumps in the United States has increased 500% in the past 15 years.
Earth energy heat pumps supplied 0.0240 quadrillion Btu of energy in 2005, according to the ‘Survey of Geothermal Heat Pump Shipments, 2005' released by the U.S. Department of Energy. That compares with 0.0054 quads in 1990.
Another 0.0088 quads was provided in geothermal direct use, which includes applications such as district heating, aquaculture pond heating, greenhouse heating and agricultural drying. That is almost double the 0.0048 quad in 1990.
Shipments of geothermal heat pumps increased 9% in 2005 over 2004 shipments, to 47,830 units, with most of the increase in ARI-325/330 systems (closed-loop ground-coupled units, compared with ARI-320 units which are water-source systems). The 47,830 units shipped in 2005 represented the largest number since DOE’s Energy Information Administration began tracking geothermal shipments in 1999.
Capacity of units grew slightly more than the number of units shipped, increasing 11% between 2004 and 2005 to 160,402 tons. The average capacity per unit has declined from 4.6 tons in 1999 to 3.4 tons per unit in 2005, which reflects the use of smaller units on commercial and school installations (zoned units) rather than a single large heat pump.
Only 265 consumers installed their own geothermal system, with most shipments of ground-coupled units (22,892) going to wholesale distributors, 11,494 to installers and 112 units to retail distributors. The report says no units were sent to exporters.
Of domestic shipments, three-quarters went to southern regions which have the most favourable temperature profile for geothermal operation or to the midwest where land access for installing closed loop systems is easiest.
Most geothermal heat pumps in the United States are sized for peak cooling and are oversized for heating, which means that the energy consumed by units in the U.S. operate up to five times more than heat pumps in Europe in heating mode.
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