21 September 2003
http://www.abc.net.au/ra/innovations/stories/s950712.htm
E-Vapcap Dam Cover - Australia
ECS Products :: Experimental dam coverTesting of material, tethering and joining of a floating cover for evaporation control and water saving
Year : 1999
Area : 1500m2
Task : Experimental dam cover- Initial testing of material, tethering, joining of floating cover. Using a light, self supporting, all black polyethylene material, the effects of wind, waves, heat, rain, sun, joining and tethering techniques were observed and recorded.
Result: Waves dampened, safe from strong wind if all tethers remained secure, rain entered storage through small drainage holes, surface temperature under the floating cover was cooler, search for a slightly heavier, purpose built material began.
About twenty years ago, when a Queensland grazier found himself carting water 20 kilometres when his farm ran out of stock water, he started researching a solution. And he discovered that by throwing a plastic cover over a four hectare farm dam, water evaporation was cut to next to nothing, even through the worst drought in a century.
Contact: Warwick Hill
Evaporation Control Systems, “Croydon Park”, Meandarra. QLD 4422. Australia
International Telephone: +61 7] 4665 6144 FAX: +61 7] 4665 6395
Email: croypk@bigpond.com
Website: http://www.evaporationcontrol.com.au/
TRANSCRIPT:
BLANCH: This is about making the most you can out of water. Australia’s not renowned for its over supply of water, in fact, we’re the second driest continent after Antarctica. Unlike Antarctica, Australia’s temperatures are such that massive amounts of water in open storages are lost to evaporation. About twenty years ago, when Queensland grazier, Warwick Hill found himself carting water 20 kilometres when his farm ran out of stock water, he started researching a solution. And he discovered that by throwing a plastic cover over a four-hectare farm dam, water evaporation was cut to next to nothing, even through the worst drought in a century. So Warwick, to give us an idea how large is a four hectare dam?
HILL : Well Desley, it’s about ten acres in area or four hectares in the metric system, it’s about 250 metres long and approximately 150 metres wide.
BLANCH : Well, it’s been described as the biggest cover that may have been actually built on the water without having to either build it on the bank of the storage or to have the storage empty before you can create the cover, so how do you do it and part of the answer I know lies in what you call the “Water whizz”, that’s like a large sewing machine?
HILL : Yes Desley, that’s right. We float our machine which has been specially designed for the job across the water joining together widths of the material section by section.
BLANCH : Now where did your idea originate?
HILL : Well, it came from trying to do some basic research to solve a problem that I had on this farm and considering as many different options as I possibly could. I referred to the CSIRO and had all the information that was currently available from anywhere in the world in front of me and, from that I reached the conclusion that there wasn’t anything that really worked at a reasonable price, so we went from there. I started with liquid films and then moved to solid films and then onto the material that we now use.
BLANCH : And where did the hunt take you for a suitable material to use to cover the water?
HILL : Well, it took me to most of the plastic manufacturing firms in Queensland for a start and then to the other states in eastern Australia. I ended up going to not only Brisbane, but also Melbourne and then finally to Sydney and that’s where we found the material that is now E-VapCap™.
BLANCH : And what is the E-VapCap made from?
HILL : It’s made from virgin grey polyethylene and it’s a manufacturing process that’s been developed and patented by the Australian subsidiary of a large American company.
BLANCH : And you’ve got it black on one side and white on the other, for what reasons?
HILL : The white is the upper side which is presented to the sun to reflect some of the solar radiation and the heat and the black is underneath – it’s a very effective barrier to all light and as a result that provides some ancillary benefits when the cover’s installed.
BLANCH : And it’s described as an enhanced buoyancy product, what does that mean?
HILL : Well, it has its own built-in cells – air cells, which enable it to float very positively on top of the water and those cells are approximately four millimetres thick and it means that the material, while always in contact with the water, is nevertheless floating above the water.
BLANCH : Now late in 2001, during one of your early trials, disaster struck – what happened?
HILL : Yes it’s a very sad memory for me, but nevertheless it did occur, it’s part of history. We had a cover installed to about 90 per cent completion. We thought we were home and hosed, we left the site late one evening and everything looked perfect, but during the middle of the night a severe windstorm blew up and got underneath the unfinished edge of the cover and once the wind was under it, there was no holding it. No-one saw it happen, but we saw the result early in the morning.
BLANCH : Wrapped around something I suppose.
HILL : Burst and blown apart and draped down the side of the water storage, one heck of a mess.
BLANCH : And a lot of money down the drain.
HILL : Exactly.
BLANCH : Now what design changes did you make to ensure that doesn’t repeat, how is the cover anchored?
HILL : Well, we made a number of changes – we went away from the original technique of joining the sections together and began welding them together which was, I think, unique. We went away from our means of anchoring the cover in place and we now trench the cover into the bank of the storage and compact the trench behind the cover, so there now is no access point for wind to get underneath the cover.
BLANCH : Just quickly, what are the estimated losses from evaporation that you’ve discovered?
HILL : Well, in Australia, Desley, they vary from a low of about a metre and a half of vertical loss of water to three metres or even higher in some of the very hot and very dry windy parts of Australia. That can equate to as much as half the water that’s in the storage, depending of course on the depth of the storage.
BLANCH : Well, evaporative losses from farm dams has always been known to be large, but it’s always been considered that the cost of the solution is far higher than the value of the water, but over the last few
years with new products and materials and some inventive solutions like yours, plus at the same time the value of water—that’s risen, has the balancing point been reached now?
HILL : I think it certainly has but it is dependent at least partly on the cost of the water that’s being put on the storage, but more importantly on the value of the product that’s been produced by the water. If you’re losing a lot of water resulting in far less production than you might otherwise achieve, if that produce is worth a lot, well then the losses in financial terms are great also.
BLANCH : Well, the cost of the E-VapCap system works out at about, as I understand it, $6.00 AUD a square metre fully installed, so for your four hectare dam cover that’s a quarter of a million dollars, how long would it take a primary producer to recoup those monies?
HILL : Well, that’s where the value of the crop that’s being produced with the water saved is really critical. If the produce is a high value crop such as grapes or vegetables or citrus fruit, then the cost can be fully recovered within one year. If you’re producing a lower value crop it naturally takes longer to recover that cost.
BLANCH : So what role could governments play if they’re serious about water use efficiency as at present your solution is not exactly a cheap option, is it?
HILL : That’s correct Desley, and I think governments are very serious about increasing water use efficiency in Australia. They are starting to try to claw-back water for environmental purposes and that’s an admirable aim. They could encourage this by when licensing future dams, new storages that are being built, they may make a pre-condition that every effort is made to limit the amount loss to evaporation and this is where we come into the story. They can encourage irrigators to finance the outlay on the cover by giving them accelerated depreciation allowances and by giving them multiple right-offs with investment allowances.
BLANCH : Now you’ve poured a lot of money into this, you’re now in the early stages of commercialisation, are you recouping some of that?
HILL : You’re right about the outflow of the money. So far it’s coming in but only slowly. We have high hopes that in the future the inflow will speed up and we’ll get back some of that or hopefully more than all of our investment costs so far.
BLANCH : Well, control of evaporation on farm dams has been the holy grail of irrigation research, do you believe you’ve achieved that?
HILL : Well, I think so Desley, I think it is a feasible alternative now and when we can produce figures that do stack up so that a farmer or an irrigator or any user of water can be convinced that the investment that he outlays in a cover is returned to him in a relatively short time, I think the job is on the way.
BLANCH : How much more engineering research do you think is necessary for the cover?
HILL : There’s certainly a fair bit more. With every cover that we install that’s bigger than the previous biggest, we’re moving into unknown territory and as a result there’s a certain nervousness about it and a bit of fear. We’re not sure how big we can go with the covers as yet and that’s where the engineering research that we hope will be undertaken during the rest of this year, is going to be vital for the further progress of the product.
http://www.abc.net.au/ra/innovations/stories/s950712.htm
No comments:
Post a Comment