Given the exigency to rein in our nation's energy consumption and carbon emissions, a nationwide deployment of Geothermal Heat Pumps (GHPs) would help mitigate our demands on the earths resources by reducing energy requirements for heating and cooling. Geothermal Heat Pump systems are a proven renewable energy resource that provides significant energy savings as compared to typical heating and air conditioning units. The energy savings are in the range of 30 to 60 percent over the traditional systems. Buildings account for nearly 40 percent of U.S. energy consumption and greenhouse gas emissions. GHP can help us avoid the construction of 91 to 105 gigawatts of electrical generation capacity nationwide by 2030. Additionally, we could reduce our utility bills by $33 to $38 billion annually (2006 rates). In order to achieve these impressive outcomes, the life cycle cost (total cost of ownership) of geothermal heat pumps must be improved. The greatest barriers to GHP implementation is their high initial cost and long payback period. Most GHPs systems use propylene glycol or ethylene glycol in the ground loop which can present an environmental risk, a disposal problem, and a higher life-cycle cost. The aim of this proposals research is to develop an economical heat transfer fluid for GHPs with superior heat transfer properties over propylene and ethylene glycol. This new fluid will not have the hazard and disposal problems of propylene and ethylene glycol. A 5-ton residential GHP can produce 660 to 880 gallons of propylene or ethylene glycol waste over its 40 year lifetime. This represents a disposal and environmental risk because glycols are soluble in water. Our patented approach includes adding small amounts of nanoparticles to the circulating fluid which results in a 2 to 3 fold increase in thermal conductivity of the mixture. The anticipated result of this research is a heat transfer fluid with improved life-cycle cost. Additionally, the improved heat transfer properties of the fluid may allow a shorter system of underground infrastructure piping and lower the initial installation costs. Our nanoparticles are easily removed and reused and will not represent a disposal problem. Hence, this new circulating fluid will have the capability to reduce the life-cycle cost of the system while still meeting the expectations of homeowners, industrial users, and equipment manufactures. The significance of this project is that there is a need to develop a new economical circulating fluid for GHPs that does not possess the harmful effects of propylene or ethylene glycol. This new fluid will improve the heat transfer efficiency over propylene and ethylene glycol. Therefore, ACTAs research covers a greener, more energy efficient GHP system
