heating water Efficient Dairy Layout and Design Hot water for milking machines Hot water for milk vats Reduce, Re-use, Recycle InfoSheet B3

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1 heatig Forty per cet of a average dairy farm s daily electricity is used for heatig this is the biggest user of power at the shed. Keep the followig priciples i mid. Match the quatity of heated to actual requiremets this is the best way to reduce costs, eergy use ad greehouse gas emissios. Reduce the amout of hot required by reviewig wash programs. Heat to the temperature required for the job every degree above requiremets meas higher costs. Deliver hot quickly, whe it s eeded this miimises heat loss. Isulate, isulate, isulate to reduce heat loss retaiig heat saves moey. Pre-heat if you ca usig from the plate cooler or usig a solar system to pre-heat makes sese. Use the best quality available high i mierals or orgaic matter reduces heatig performace. Pre-heatig is good for the eviromet For every 1 C warmer that eters the electric hot service greehouse emissios are reduced by 139 g per 100 litres of heated. Efficiet hot use i the dairy is all about deliverig at the right temperature with miimal heat loss. Eergy efficiecies also ca be gaied by capturig some of the heat available durig milkig a by-product of milk harvestig. Pre-heatig makes sese but aloe it is ulikely to get it to the required temperature. Below are some of the ivestmet optios curretly available that make use of pre-heatig. Costs, eergy usage ad greehouse gas emissios ca all be reduced by proper matchig of the quatity of heated with what s eeded daily. Pre-heatig optios Heatig or boostig optios Cold Warmed Heated Ed use Water Solar Heat recovery Heat capture Heat pump Gas Electric storage Gas storage Solid fuel Hot for milkig machies The table below is a guide to how much hot is required to effectively wash ad saitise a milkig machie with the most commoly used procedures i Australia 3 cycles per wash (warm pre-rise at 38 C, hot deterget wash, hot saitise). As a geeral rule, allow 6-8 litres per uit. I the warm pre-rise cycle aroud 25-35% of the volume is hot. No. uits Hot per wash (litres) Hot for milk vats heat ONLY WHAT YOU NEED Nearly all moder milk vats have semi or fully automated wash systems, but hot use varies accordig to wash program selected ad cleaig system desig. As a geeral guide, the amout of hot required for effective cleaig is 1-3% of the milk vat s storage capacity. For older vats that require maual cleaig, the quatity of hot required depeds o idividual cleaig practices. Milk vat capacity (litres) Hot per wash (litres) 6, , , , , , Dairy Idustry Reduce, Re-use, Recycle IfoSheet B3 Efficiet Dairy Layout ad Desig

2 Heatig Other hot requiremets Reduce hot eeded Hot is required for geeral washig up, dilutig teat disifectat (after the has cooled), mixig calf milk ad other geeral duties aroud the dairy. Allowig litres per day should be sufficiet for most situatios. Carefully review your wash program. Check you are ot overusig hot quatities. Check the temperature of the wash i the drum as the wash cycle commeces it should ot exceed 85 C. Durig recirculatio (hot wash cycle) the drum should be aroud 20% full as the wash returs. If it is more, the smaller wash quatities could be cosidered. Check out detergets that are effective at lower temperatures. Usig a chemical saitiser i the fial wash cycle will also reduce the heatig demad. Capture the fial rise for use ext time. Well isulated wash drum ~20% of the wash is always i the drum durig recirculatios Wash retur pipe How much hot do I eed? Milkig machie litres/wash x washes/day (a) Total = litres/day plus Vat litres/wash x washes/day (b) Total = litres/day plus Other uses (c) litres/day Total hot per day (a) + (b) + (c) litres It souds obvious, but if it is possible to use warmed, go for it, as it saves eergy ad costs. Pre-heatig optios iclude solar systems, heat pumps ad heat recovery ad recapture systems. Pre-heatig systems ca achieve temperatures of up to 70 C. I some situatios eve higher temperatures ca be achieved. Preheat No preheated Solar hot heater Heat recovery systems Which system is right for me? Dedicated Commets isulated storage tak required No Traditioal systems use the most eergy to achieve the required usage temperature. Yes A extremely effective way to reduce electricity cosumptio ad greehouse gas emissios. Performace is subject to locatio, positioig ad climatic coditios. Yes This system uses the heat geerated by the refrigeratio uit whe coolig milk i the vat. Performace is related to the amout of ruig time of the refrigeratio uit(s) the loger they ru the greater the heatig. Well suited to herds with split/all year roud calvig patters, as daily milk coolig volumes are more cosistet. Water temperatures up to 70 C are possible. Heat Yes This ivolves capturig the heat i the milk as it passes through the plate cooler. The amout of heat recapture is small but ca be used for udder washig, mixig calf milk powder ad supplemetig had washig facilities. Water temperatures of aroud 30 C are possible. See IfoSheet B4: Coolig Milk (page 5) for details. Heat pump Yes Pre-heat Heat pumps extract heat from the air, or the groud ad trasfer it to the. Performace is improved whe a solar booster is used. Usig reewable eergy source to power a heat pump will reduce greehouse gas productio. Water temperatures of aroud C are typically possible. 2

3 Heatig Istataeous heaters By defiitio, istataeous systems heat oly the required ad do ot use a storage tak. They ca operate o atural gas, LPG or electricity. Gas models are available with either electroic igitio or a pilot flame. However, sice istataeous systems caot deliver hot at the required flow rates they would ot suit milkig machie or vat washig purposes. Hot flow rates of litres/ miute are possible. These rates ca be achieved if the temperature oly has to rise by 25 C. Requiremets of greater temperature icreases will result i lower flow rates. Solar hot heaters These systems eed: solar thermal collectors there are three mai types (see below); a fluid system to move the absorbed heat from the collector to its poit of usage these ca be a ope or closed circuit (see below); ad a reservoir or tak for pre-heated ad subsequet use. Formed plastic collectors Large, flat array of ribbo plastic tubes, ofte dark i colour, through which is circulated ad heated. Commets: These produce tepid temperatures. Commoly istalled to heat used i swimmig pools. Flat collectors These are flat, glass-froted isulated paels that cotai thi sheets of absorber materials. Fluid is circulated through copper pipes to remove the heat from the absorber ad trasported to a isulated tak or heat exchager. Commets: Most commoly used for heatig. Also used i solar space heatig systems. Ca be either ope circuit or closed circuit (see over page). Evacuated tube collectors Comprise rows of parallel mouted trasparet glass tubes. Each tube cotais a absorber tube. The sulight passes through the outer glass tube heatig the absorber tube which has bee covered with a special light-modulatig coatig. The heated fluid ca be used directly or heat via a heat exchager. Commets: By desig, these types of collectors capture heat more efficietly. They ca achieve much higher temperatures tha flat collectors. Ted to be more expesive. 3

4 Heatig Ope circuit vs closed circuit I a ope circuit system, flows directly through the solar collectors ito the storage tak ad is the available for use. I a closed circuit system, a fluid other tha (such as glycol) flows through the collectors ad trasfers this heat to i the storage tak through a heat exchager. Closed circuit systems are most commoly used for frost protectio or whe the is corrosive. Heat recovery: vats This system utilises the heat geerated by the milk vat s refrigeratio uit. It ivolves a storage tak similar to a mais pressure hot service cotaiig coils through which the heated refrigerat passes. It ca heat to aroud C ad is geerally used for cleaig the vat. It also ca be used as a supplemet to the mai hot system. Pre-heat The quatity of hot produced ad the temperature achieved depeds upo: The temperature of the milk eterig the vat. The lower the temperature the less heat produced. The volume of milk to be cooled by the vat s refrigeratio system. The greater the volume of milk the more heat produced. The quatity ad startig temperature of the. Heat pump heaters Heat pumps work like the vat s refrigeratio system but i reverse they extract heat from the eviromet. Heat pumps have bee widely used for may years. There are several types of heat pump heaters ad each has various cofiguratios: Air source heat pump systems (most commo) extract the heat from the air. They ca be foud i domestic applicatios. Water source heat pump systems use a loop or body of to exchage heat. They are very efficiet because of the temperature variability i the body of is relatively smaller tha that of the ambiet air. These are used o larger commercial applicatios. Groud source (or geothermal) heat pump systems use coils buried deep i the groud where the temperature is stable throughout the year also very efficiet. Solar boosted heat pump systems utilise solar collectors as the evaporator, further improvig performace. Photovoltaics (system that coverts the su s eergy ito electricity) ca be employed to power the heat pump. This would make this system of heatig extremely eergy efficiet. Heat recapture: plate cooler The heat removed from the milk as it passes through the plate cooler ca be trasferred, via aother plate cooler, to the supplyig the hot storage system. See IfoSheet B4: Coolig Milk (page 5) for details. I the cool climates of souther Australia, greehouse gas emissios from solar boosted heat pump systems ca be similar to or less tha those from a solar heater with a electric booster. However, i most other parts of Australia this would ot be the case. Source: Australia Greeh ouse Office 4

5 Heatig The optios for heatig or boostig to temperatures aroud 85 C for milkig machie washig are limited. A electric heatig heat ad boost elemet is as of Jauary 2008 the simplest method. The trick is to maximise the pre-heatig performace. This will esure eergy for electric heatig will be miimised as will greehouse gas emissios. Heatig/ booster system Electric heatig elemet Istataeous gas Which system is right for me? Dedicated isulated storage tak required Yes No Suitable for applicatios that do ot require temperatures >65 C A dedicated mais pressure uit for vat washig Effectiveess ca be ehaced if is pre-heated. Not suitable for high flow rate demads. Gas storage Yes Very limited applicatios (very large capital ivestmet required). Multiple uits required. Suitable for applicatios that do require temperatures >65 C Oly as pre-heatig system Covetioal electric storage hot heaters By far the most commo way of heatig i the dairy. Heatig of ormally occurs durig off-peak electricity tariff coditios geerally this is betwee 11pm ad 7am each day. Nearly all electric hot heaters have a additioal elemet that acts as booster. The booster is tured o via a maual switch. I gravity-fed systems, the draw from the storage tak is oly repleished durig heatig. This miimises the loss of temperature iside the tak but ecessitates a storage capacity to cater for the whole day s requiremets. I vat wash systems, a dedicated mais-pressure hot service is used. Sice most vats require a lower wash temperature (~65-70 C) havig a dedicated hot system will reduce heatig eergy requiremets. A heat recovery system would be worthwhile alterative. Gas storage hot heaters Gas storage hot heaters are commoly available for domestic applicatios. They ca deliver at temperatures of aroud C ad so have very limited applicatio i the dairy. Commercial gas storage hot heaters ca deliver at temperatures of up to 85 C. But to achieve flow rates required for dairy use the capital expese makes this a prohibitive optio. Booster systems Esurig a reliable supply of hot at temperatures required to wash the milkig machie (above 80 C) will require a electric booster system ad a dedicated, well-isulated storage tak. For applicatios where the maximum required temperature is less tha 65 C other booster systems could be cosidered. Electric booster: usig a covetioal electric hot system. A separate holdig tak would be required if the electric elemets were to oly operate durig off-peak times. Gas booster: this relies o heatig the just prior to use. Ofte referred to as cotiuous flow or istataeous. Gas boosters caot heat quickly eough to meet the cleaig requiremets i the dairy. Therefore, a separate holdig tak would be required or the heat boosted could be recirculated i the storage tak. This tak would store eough hot to cater for the ext milkig s requiremets. Gas booster systems ca be effectively icorporated ito preheatig systems, further reducig the reliace o electric elemet heatig. Solid fuel boosters heat through a heat exchager, commoly kow as a wet back system. Solid fuel booster ad gas booster systems produce less greehouse gas emissios tha electric boosted systems. 5

6 Heatig The optios Eergy efficiet ways of heatig Alterative pre-heatig optios Solar collector Heat pump Heat recovery tak with electric booster Preheatig At best ~30 C If <60 C If >60 C Well isulated hot storage tak Istataeous gas hot heater Gas hot storage heater Booster/heatig 65 C 85 C Heatig to 85 C Heatig to 65 C Electric hot storage heater with rapid flow 2 outlet Operates o off-peak tariff rates Electric heatig ad booster elemets All uses (<85 C) except automatic vat wash systems Miscellaeous uses (<65 C) with low flow rates, icl. some automatic vat wash systems Durig periods of high solar gai (e.g. summer) heatig with electric elemets or gas may ot be required Mais pressure Alterative gas heatig optios Select uits desiged for commercial applicatios May require multiple uits to achieve desired flow rate 6

7 Heatig sceario Ke is lookig to milk aroud 1,100 cows o a ew farm orth of Mt Gambier. The ew 60-uit rotary dairy will be built o a gree field site. Ke is kee to icorporate eergy efficiecy i as much of the ew dairy as possible. Efficiet use of is aother of Ke s objectives. Ke has idetified three areas where he thiks efficiecy improvemets will have the greatest impact. The first is i the way is heated; the secod is how his milk pre-coolig could be improved (refer to IfoSheet B4: Coolig Milk for details); ad the third area is how is used at the dairy ad where savigs could be made. Of course, eergy efficiet lightig ad other power savig devices will be icorporated ito the shed desig. Improvig heatig As there will be differet staff workig at the ew dairy, Ke says simplicity is very importat. A solar hot system with evacuated tube collectors will be used to pre-heat the. The pre-heated will be stored i three highly isulated taks from where it will be fed ito the electric hot services. The 40,000 litre vat will have a heat recovery system icluded. The calculated amout of hot required each day at the ew dairy will be as follows: Rai will be captured ad used for all equipmet cleaig. A bore o the farm will be used to supplemet the rai taks as required. The bore has bee tested ad foud to be less tha 100 ppm i Total Hardess suitable for equipmet cleaig. The bore temperature is aroud 18 C for most of the year. These are coservative assumptios. Details Period 300 days Water from bore 18 C 90 C hot (milkig machie) 2,000 litres/d 90 C hot (misc.) 200 litres/d 65 C tot (vat) 600 litres/d Without a pre-heatig system Power to heat to 90 C kwh/d Power to heat to 65 C 37.7 kwh/d Total 260 kg CO 2 e/d 78,000 kg CO 2 e/yr With a pre-heatig system Assumptios: will be pre-heated to at least 40 C every day ad 60 C every 2d day Power to heat to 90 C kwh/d Power to heat to 65 C kwh/d Total kg CO 2 e/d 40, kg CO 2 e/yr Savigs kwh/d kg CO 2 e/d 37,453 kg CO 2 e/yr Solar hot system will pre-heat this. Heat recovery system will pre-heat this. The heat recovery system will do away with 2 x 400 litre mais pressure hot service uits. Over the summer moths the electric hot heaters will hardly be o for log. A estimated 48% reductio i greehouse gas emissios about 37.5 toes per year. 7

8 Heatig Water quality Water cotaiig high levels of mierals ca reduce heatig performace ad shorte equipmet life. Orgaic matter i the ca also build up formig a sludge that further reduces heatig performace. Sacrificial aodes placed iside hot storage taks offer some protectio agaist corrosio but do ot completely compesate for havig a supply of good potable quality. For more iformatio o quality See IfoSheet C1: Water at the Dairy. Is my existig system efficiet? Workig out if your curret system is efficiet should be the first step eve if you are plaig a upgrade or ew dairy. The efficiecy of electric storage hot systems ca be greatly improved by reducig thermal losses ad miimisig heatig requiremets. Thigs to check: Quatity of heated matches quatity required. A efficiet ad effective wash program is used. The wash programs eable thrifty use of hot fial hot rise is recaptured. Storage tak is positioed away from drafts ad breezeways. Additioal isulatio is wrapped aroud the storage tak (esure relief valves ad ay vets are ot obscured or restricted). Fast delivery mechaisms: 2 outlet valve ad pipe. Thermostat is accurate. Oly heat the eough to achieve 85oC i the wash drum. All hot pipes are well isulated. Isulatig the wash supply lie to the jetters is also advatageous. Good quality (potable) supply is used. The warmest available (good quality) is used to fill the storage tak. All leaks are rectified. Elemets ad aodes are well maitaied (a ispectio ad service program is i place). The best (off-peak) tariff rate is used. To calculate hot requiremets see page 2. Further iformatio Australia Greehouse Office Reewable Eergy Certificates (RECs) IfoSheet A4: Reewable Eergy Sources Liks South Australia Solar Hot Water Heater Rebate Scheme hot_.html Rebates ad assistace Rebates are available from Federal, State ad some local Govermets. Some of the product maufacturers ad utility supplies also offer assistace ad icetives. Check with your local coucil for applicable rebates ad eligibility criteria. As at October 2007 there are SA rebates for commercial busiesses, however, rebates are chagig cotiually so please check the lik o this page. Sposored by Disclaimer: Although DairySA has take all reasoable care i preparig this advice, either DairySA or its officers or agets accept ay liability resultig from the iterpretatio or use of the iformatio set out i this documet. Jauary 2008 SUBS/BP/