P. Hughes.

ORNLTM2008232; DE2009948543, 1 Dec 2008, pp. 47.

More effective stewardship of our resources contributes to the security, environmental sustainability, and economic well-being of the nation. Buildings present one of the best opportunities to economically reduce energy consumption and limit greenhouse gas emissions. Geothermal heat pumps (GHPs), sometimes called ground-source heat pumps, have been proven capable of producing large reductions in energy use and peak demand in buildings. However, GHPs have received little attention at the policy level as an important component of a national strategy. Have policymakers mistakenly overlooked GHPs, or are GHPs simply unable to make a major contribution to the national goals for various reasons. This brief study was undertaken at DOE's request to address this conundrum. The scope of the study includes determining the status of global GHP markets and the status of the GHP industry and technology in the United States, assembling previous estimates of GHP energy savings potential, identifying key barriers to application of GHPs, and identifying actions that could accelerate market adoption of GHPs. The findings are documented in this report along with conclusions and recommendations.

Ebru Kavak Akpinar and Arif Hepbasli.

Building and Environment, Vol. 42, No. 5, May 2007, pp. 2004-2013.

Ground source heat pumps (GSHPs), also known as geothermal heat pumps (GHPs), have been widely used for years in developed countries due to their higher energy utilization efficiencies than those of both conventional heating and cooling systems. However, they have been applied to the Turkish residential buildings since 1997. This study deals with the exergetic performance evaluation of two types of GSHP systems installed in Turkey based on the actual operational data. The fist one is a GSHP system designed and constructed for investigating geothermal resources with low temperatures, while the second one is a GSHP system with a vertical ground heat exchanger. In the analysis, four balance (mass, energy, entropy and exergy ) equations are applied to the two GSHP systems considered for modeling purposes in a tabulated form. Exergy (second law) efficiency values for both systems are given, while exergy destructions in each of the system components are determined to assess their individual performances by presenting the potential for improvements. It may be concluded that the exergetic evaluation method presented here may be applied to other GSHP systems worldwide as a useful tool, which is a way to sustainable development. C specific heat (kJ/kg K) rate of exergy (kW) ex specific exergy (kJ/kg) h specific enthalpy (kJ/kg) I current (A) rate of irreversibility (kW) mass flow rate (kg/s) P pressure (kPa) or power (kW) rate of heat transfer (kW) s specific entropy (kJ/kg K) rate of entropy (kW/K) T temperature (C or K) V voltage (V) W total uncertainty rate of work, power (kW) x independent variable rate of exergy (kW) Greek symbols *v flow exergy (kJ/kg) *h efficiency (dimensionless) power factor (dimensionless) Indices a adiabatic act actual C Carnot CH chemical comp compressor cond condenser cw condenser water dest destroyed el electrical evap evaporator ew evaporator water fc fan-coil unit gen generation gh ground heat exchanger gw geothermal water h heating H high temperature HP heat pump in inlet k location KN kinetic L low temperature m mechanical O overall out outlet P performance PH physical PT potential R rational r refrigerant ro rotameter s isentropic sh space heating sl system leakage t thermal td temperature difference tv throttling valve w water wa water/antifreeze solution 0 dead state 1 initial state 2 final state II exergy (second law) .(over dot) quantity per unit time Abbreviations GHP geothermal heat pump GSHP ground source heat pump

Michael Kummert, Michel Bernier, Andrea Costa and Jean Paris.

International Journal of Environmental Studies, Vol. 64, No. 4, Aug. 2007, pp. 467-487.

This article compares the performance of geothermal absorption and compression heat pump systems for space conditioning. The comparison is performed on an R-2000 residence for three Canadian locations representing three different climates and energy contexts: Montreal, Edmonton and Vancouver. The analysis is based on simulations carried out using TRNSYS. Results indicate that the required length of the geothermal heat exchanger is significantly different for the two types of heat pumps (compression and absorption). In Edmonton, geothermal absorption heat pump systems have a lower life-cycle cost and emit fewer greenhouse gases than geothermal compression heat pump system. In Montreal, both systems have similar life-cycle costs. Since electricity is mainly hydro-based the greenhouse gas emissions are much lower for the compression system. In Vancouver, the compression system has both lower life-cycle costs and lower greenhouse gases emissions.

Valentin Trillat-Berdal, Bernard Souyri and Gilbert Achard.

Applied Thermal Engineering, Vol. 27, No. 10, July 2007, pp. 1750-1755.

The study discussed relates to the design and development of a process consisting of combining a reversible geothermal heat pump with thermal solar collectors for building heating and cooling and the production of domestic hot water. The proposed process, called GEOSOL, has been installed in a 180m2 private residence in 2004. This installation is the subject of long-term experimental follow-up to analyse the energy-related behavior of the installation at all times of the year. In addition, different configurations of this combined system (geothermal heat pump and thermal solar collectors) have been defined and will be simulated numerically using TRNSYS software. A comparative analysis of these different alternative versions will be conducted to determine the best configuration(s) of the GEOSOL process in terms of energy, economical and environmental performances.

Zhi Zhong and Zhi-wei Tang.

Kezaisheng Nengyuan (Renewable Energy Resources), Vol. 25, No. 2, Apr. 2007, pp. 94-96.

Energy pile is the new method to exchange heat for geothermal heat pump system. It combines with the building frame and take advantages of the area of the buildings to exchange heat from piles to the surrounding soil, as the result, it reduces the expense for boring holes and burying pipes. This paper gives the main types, the typical system design with the energy piles and the cautions when using them in the practices.