Geothermal systems bring efficiency and reduced costs.
Geothermal heat pump A geothermal heat pump system is a heating and/or an air conditioning system that uses the Earth's ability to store heat in the ground and water thermal masses. This system will take advantage of a land mass as a heat exchanger to either heat or cool a building structure. systems are gaining prominence because of the move toward more efficient, sustainable building practices and the rapidly rising costs of fuel.
Their principle of operation is simple; the earth's relatively constant ground temperature serves as a heat source in the winter and a heat sink A material that absorbs heat. Typically made of aluminum, heat sinks are widely used in amplifiers and other electronic devices that build up heat. Small heat sinks are the most economical method for cooling microprocessors and other chips. in the summer. And, coupled with heat pump heat pump: see air conditioning.
Device for transferring heat from a substance or space at one temperature to another at a higher temperature. technology, they produce warm air or hot water in the winter or cool air or chilled water in the summer.
There are two basic categories of geothermal ge·o·ther·mal also ge·o·ther·mic
Of or relating to the internal heat of the earth.
ge systems: open loop and closed loop systems. In open loop systems the water that is circulated through the heat pump units comes in direct contact with the earth, in closed loop systems the water runs through tubing that is buried in the ground.
One type of open loop system that is suitable for areas where the earth is made up of bedrock and where ground water yields are low is the standing column well system. Standard open loop systems require relatively large yields of reliable ground water. For example, a 100-ton capacity system requires 200-300 gallons per minute of ground water. A standing column system uses less ground water because most of the water is recirculated. The standing column well requires good bedrock to allow for a deep, uncased well, a reasonably high static water level within the well and a minimal amount of ground water flow for what is known as bleed flow. A 100 ton capacity standing column well system with a 10% bleed rate would require a ground water yield of approximately 30 gallons per minute.
Standing column wells are 1,500 foot deep, 6" in diameter with an approximate capacity of 35 tons. A 4" pipe runs in the center of the well and draws water from the bottom of the well. Water is returned to the outer ring at the top of the well. As the water in the outer ring is drawn to the bottom of the well it transfers its heat to the earth.
A typical drilling rig is the size of a cement mixing truck and about 30 feet tall. High-pressure air is used to blow out rock fragments and water during drilling. A 100 yard dumpster located next to the rig is used to collect the drilling cuttings and water. The water is allowed to settle clear and then drained. The cuttings are hauled away. Each well takes about 6 days to drill.
Each standing column well has approximately 10 times the capacity of a vertical closed loop well. This allows standing column wells to be installed on sites with limited space for well fields. Standing column well systems have been installed beneath city sidewalks to serve buildings that have no available space for traditional vertical closed loop well systems and low ground water yields that preclude the use of traditional open loop systems.
The primary advantage of a geothermal system is its high-energy efficiency and low annual energy costs. In comparative terms, geothermal systems have a cooling energy efficiency rating (EER EER - An extended entity-relationship model. ) of 20 and over, while conventional systems have EER ratings of between 10 and 16. Other advantages are no use of fossil fuel fossil fuel: see energy, sources of; fuel.
Any of a class of materials of biologic origin occurring within the Earth's crust that can be used as a source of energy. Fossil fuels include coal, petroleum, and natural gas. on site, no outdoor above grade equipment and zero exterior noise pollution.
The cost of geothermal systems varies depending on the type of system used. Open loop systems typically have the lowest first cost with standing column and closed loop wells being higher in cost. Ground heat exchanger heat exchanger
Any of several devices that transfer heat from a hot to a cold fluid. In many engineering applications, one fluid needs to be heated and another cooled, a requirement economically accomplished by a heat exchanger. costs for standing column and closed loop wells run from $1000 per ton up to $2000 per ton.
Average payback Payback
The length of time it takes to recover the initial cost of a project, without regard to the time value of money. due to energy savings can be 5-7 years and even lower if incentives or rebates are available to offset first costs.
BY JOHN RICE, PE, AKF AKF Aga Khan Foundation (Geneva, Switzerland)
AKF Australian Koala Foundation
AKF American Kidney Fund
AKF Aktivkohle (German: Activated Charcoal; filter/canister)
AKF Acute Kidney Failure ENGINEERS, LLP LLP - Lower Layer Protocol