DEEP LAKE WATER COOLING 8
Deeplake water cooling
Howthe technology works
Deeplake water cooling makes use of cold water, which is pumped frombeneath a lake as a heat sink for environment control systems. InToronto Canada, this source of renewable energy is used in the cityto air conditions buildings. Technically, this cooling plant inToronto is the largest geothermal cooling system in the world.However, rather than using ground stored energy, it utilizes thenatural coldness Ontario Lake (Waldron, 2006).
Thegenerated heat in the customer buildings does not go back to thelake, but rather it is taken through into Enwaves’s system beforebeing conveyed into the city’s drinking water delivery. Once in theconveyance system, the water then makes its way to showers and tapsin offices and homes. Uncomplicated heat exchangers at Enwaves’scustomer sites and cooling facilities take heat from within thebuildings to the outside surroundings in a low effect, sustainableway (See the figure below) (Eliadis, 2003).
At3.98 °C, water becomes most dense at standard atmospheric pressure.Therefore, as it cools below 3.98 °C the density decreases and thewaters rise. An obvious example for this phenomenon is that icefloats. When the temperature increases above 3.98 °C, the density ofwater also decreases causing it to rise. This explains why lakes aremuch warm superficially during summer. The combination of the twoeffects infers that the base of nearly all deep water bodies situatedat a good distance from the equatorial regions remains constant at3.98 °C.
Airconditioners act as heat pumps. In the summer, when exterior airtemperatures exceed the interior temperature of the building, by useelectricity, air conditioners transmit heat from the cooler chambersto the warmer exterior chambers of the building- a process thatrequire electrical energy.
Contraryto residential air conditioners, a majority of current systems ofcommercial air conditioning do not transmit heat outright into theair outside. The thermodynamic effectiveness of the whole system canbe enhanced by making use of evaporative cooling. Here the heat ofthe water is decreased close to the temperature of the wet-bulb viaevaporation process in a cooling tower. This chilled water isinthe heat pump as the heat sink (Waldron, 2006).
Deeplake water cooling gives room for an even higher thermodynamiceffectiveness by making use of a deep lake water. This water,compared to the ambient temperatures of the wet bulb, is normally ata lower warmth rejection temperature. The higher effectiveness leadsto less usage of electricity. For a number of buildings, the deeplake water is adequately cold to the extent that the refrigerationpart of the air conditioning mechanism can sometimes be disconnected,and the interior heat of the building can be transmitted straightawayto the heat sink in the lake water. This process is as free coolinghowever, in the real sense it is not free since fans and pumps run tomobilize the building air and the lake water (Waldron, 2006).
Onemajor befit of this type of cooling is that the energy is duringpeak load periods for instance summer afternoons, when a considerableamount of the entire loads of the electricity grid is airconditioning.
Whereis it currently being used
SinceAugust 2004, the Enwave Energy Corporation located in TorontoOntario has been operating deep lake water cooling project. Thesystem gets water from Lake Ontario via tubes extending fivekilometers into the lake, stretch to a depth of eighty-three meters.This scheme is a portion of a unified district cooling scheme thatruns throughout Toronto`s commercial district, and possess 59,000tons of cooling power. Currently, the system has sufficientcapability to chill 3,200,000 square meters of office space.
TheEnwave system only makes use of water that is intended to meetdomestic water needs of the city. As a result, the Enwave system isenvironmental friendly since it does not contaminate the lake with acloud of waste heat (Eliadis, 2003).
Inthe country, buildings in Halifax and Vancouver make use of oceanwater for a few small cooling applications. Throughout Asia, Europe,and of late, in Hawaii, There are various similar systems that havebeen set up. Toronto’s water cooling scheme is currently thelargest deep-water-lake cooling system in the whole world (Eliadis,2003).
Froman engineering standpoint, the concept of a deep lake is not uniquebut is distinguished in Toronto because of the large scaleconstruction. The company of Enwave has constructed a remarkable sumof infrastructure for this scheme, with the majority of them being inthe underground where they are not visible.
Theprospects in Canada for broadening deep water cooling are prettylarge. Both Toronto and Halifax could significantly increase theirutilization of this technology without jeopardizing the environment.Victoria, Yellowknife, Prince Rupert, Hamilton, Vancouver, St. Johnsand Kingston, are among the cities that could utilize thistechnology. Additionally, there are many smaller centers situatedadjacent to deep volumes of cold water that have chances of usingthis cooling technology (Eliadis,2003).
Benefitsof this technology
Contraryto customary air conditioners or chillers that need a much ofelectricity to generate cool air, Enwaves deep lake water coolingscheme uses comparatively little electricity to run the pumps thatmove cold water from systems out to consumer buildings via a networkof pipes in the underground. Since heat is only pumped or moved fromone point to another, this method of cooling can spare some buildingsup to 95 % of the electricity needed for air conditioning. Inaddition to multiple gallons of clean drinkable water every year thatwould differently be used to move heat out to the environment inconventional chiller plants.
Thesesavings in energy translate into taking away considerable electricaldemand from the power grid in Toronto particularly in summer when theambient temperatures are high. In this period, the electrical systemis normally at its maximum capacity. This method of cooling cuts downon the emissions of carbon dioxide and removes countless number ofharmful refrigerants from consumer buildings (Waldron, 2006).
Withthe realization of 60 to 95 % of energy savings via the use deep lakewater cooling in place of conventional chillers, a building isqualified for up to ten LEED points in several categories if it makesuse of the service. Owners of buildings can as well convert hugemechanical spaces initially designed to shelter mechanical coolingapparatus in a building into income generating parking, storage, orrental, commercial space, making more effective use of the groundarea.
SinceToronto’s water cooling scheme uses insignificant electricity onthe inside, it dissociates the service rates from unpredictableutility markets, presenting non-volatile Consumer Price Index-linkedrate escalations every year. This implies that a property owner isusually in a position to foretell their cooling costs for many yearsto ahead, rather than constantly adjusting leasing rates on the basisof increasing power prices (Waldron, 2006).
Downsideto using this technology
Inlight of the extremely high costs linked with the distributionsystem, Toronto’s deep lake water cooling is geographically boundto the city’s downtown center. For that reason, expanding thesystem’s access to link smaller buildings beyond the fiscaldistrict is not practical.
Onthe other hand, with regard the property holder, there are norestrictions inside their property. offersat least a similar service as customary chillers, and regularlyprovides more suppleness to building operators to upgrade conditionsin tenant spaces via finely adjusting the measure of cooling that is (Waldron, 2006). Although the effect of this method of cooling isoften positive, some worries have been seen that, if over-utilized,the source of the cold water could suffer heat pollution. This wouldhave a negative effect on species` composition and the habitat. Inthe seas, such effects might take place at the locally, although thequantity of heat generated is tiny to make an impact on a largescale. Lakes are another issue (Eliadis, 2003). An examination ofLake Ontario projected more than 20,000m3/s of water that could bedrawn out from the lake and be utilized for cooling without alteringits physical attributes. On the contrary, The Great Lakes couldproduce extremely huge quantities. The maximum quantity will be lowerfor minor lakes, though, and ought to be in discussions on themaintainability of deep water cooling making use of lake water.
Waldron,L. (2006). DeepWater Cooling.Retrieved from: retrieved from http://crcresearch.org/case-studies/case-studies-sustainable-infrastructure/energy/deep- water-cooling
Eliadis,C. (2003). DeepLake Water Cooling. A Renewable Technology [pdffile]. Retrieved from:http://v1.electricalline.com/images/mag_archive/25.pdf
Wilcox,A. (2013). Deepwater cooling improves building efficiency.Retrieved from: http://www.reminetwork.com/articles/deep-water-cooling-improves-building-efficiency