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Solarbee installation kicking off in Lake Burley Griffin.

johnboy 26 September 2011 30

The National Capital Authority has announced they’re installing solar powered water circulators into Lake Burley Griffin tomorrow which we understand will be the brightly named Solarbees we looked at in June.

“There’s strong scientific evidence that water circulators can help reduce the intensity of blue-green algae blooms.”

“The nutrient that comes down the river is in a bound form, which blue-green algae cannot readily access. When it hits stratified water it becomes unbound. The water circulators will interrupt the stratification of the water in the lake, so the nutrient can stay bound.”

Two sites have been selected for the trial – one on the river, and the other a lake basin. Each circulator site will be paired with another untreated site with similar characteristics, so there is scientific comparison of the water quality testing results.

“The first water circulator will be installed in Molonglo Reach, with a control site upstream on the Molonglo River,” Mr Rake said.

“The second will be installed near the swimming beach at Yarralumla Bay, and it will be paired with a site in Orana Bay for testing.”

If the trial is successful, the NCA will consider the installation of more units throughout the lake

The first year of the trial, with the two units, will cost $350,000.

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chewy14 chewy14 10:22 pm 26 Oct 11

Bramina said :

Oops, those codes didn’t work. This version is more readable.

These solar bees have three 80W solar panels. But solar panels do not always produce full power, the sun needs to be pointing directly at them for that. Given that they all point in different directions, the sun moves all over the sky and it’s night for half a day on average, plus its cloudy sometimes, lets say they only produce a quarter of that on average – 20W.

The cost of 20W at Actew AGL’s retail prices (15c/kWh) is 0.3c per hour.

In other words, the government has just spent $350,000 on a one year trial of two water mixers that consume 0.3c of electricity per hour, just $25 per year.

Just googling electric motor, I came across this motor which can produce 750W for only AU313.50. That is about 40 times more powerful than what the solar bees can sustain.

But let’s consider how much water this pump claims to pump: 2650L per minute at maximum power. I find this dubious because I can’t find a pump that does anything like 2650L per hour at 20W. Laminar flow might make the pump twice as efficient, but I can’t see how it would make it 60 times more efficient than other people can achieve.

Anyway, assuming that it always works at maximum power, the solar bee would pump 1,300,000m3 every year. That’s one 25th of the lake every year. But the International Lake Environment Committee says that the residence time (the amount of time it takes the lake water to replace itself) is 0.2 years. In other words, the lake replaces its water five times a year (it does have a catchment of 1,865 square kilometres). So, nature turns over the lake water 125 times faster then the solar bee.

We taxpayers are paying $350,000 for this!

It’s not about moving the water out of the lake, its about moving the stratified water around when its in the lake.
And did you miss the bit where the 350k also includes the running of the trial for the first year?

Bramina Bramina 9:56 pm 26 Oct 11

Oops, those codes didn’t work. This version is more readable.

These solar bees have three 80W solar panels. But solar panels do not always produce full power, the sun needs to be pointing directly at them for that. Given that they all point in different directions, the sun moves all over the sky and it’s night for half a day on average, plus its cloudy sometimes, lets say they only produce a quarter of that on average – 20W.

The cost of 20W at Actew AGL’s retail prices (15c/kWh) is 0.3c per hour.

In other words, the government has just spent $350,000 on a one year trial of two water mixers that consume 0.3c of electricity per hour, just $25 per year.

Just googling electric motor, I came across this motor which can produce 750W for only AU313.50. That is about 40 times more powerful than what the solar bees can sustain.

But let’s consider how much water this pump claims to pump: 2650L per minute at maximum power. I find this dubious because I can’t find a pump that does anything like 2650L per hour at 20W. Laminar flow might make the pump twice as efficient, but I can’t see how it would make it 60 times more efficient than other people can achieve.

Anyway, assuming that it always works at maximum power, the solar bee would pump 1,300,000m3 every year. That’s one 25th of the lake every year. But the International Lake Environment Committee says that the residence time (the amount of time it takes the lake water to replace itself) is 0.2 years. In other words, the lake replaces its water five times a year (it does have a catchment of 1,865 square kilometres). So, nature turns over the lake water 125 times faster then the solar bee.

We taxpayers are paying $350,000 for this!

Bramina Bramina 9:45 pm 26 Oct 11

chewy14 said :

In other words:

“I have no idea what I’m talking about, I don’t know what these things do and I didn’t even bother to look at their website that was linked to see the specifications for them:”

http://lakes.solarbee.com/products

Well allow me to retort.

These solar bees have three 80W solar panels. But solar panels do not always produce full power, the sun needs to be pointing directly at them for that. Given that they all point in different directions, the sun moves all over the sky and it’s night for half a day on average, plus its cloudy sometimes, lets say they only produce a quarter of that on average – 20W.

The cost of 20W at Actew AGL’s retail prices (15c/kWh) is 0.3c per hour.

In other words, the government has just spent $350,000 on a one year trial of two water mixers that consume 0.3c of electricity per hour, just $25 per year.

Just googling electric motor, I came across [url=http://www.roycecross.com.au/product_list/pages/product.php?Operation=SetSessionVariable&Variable[ProductCodeID]=S-75C6CCG]this motor[/url] which can produce 750W for only AU313.50. That is about 40 times more powerful than what the solar bees can sustain.

But let’s consider how much water this pump claims to pump: 2650L per minute at maximum power. I find this dubious because I can’t find a pump that does anything like 2650L per hour at 20W. Laminar flow might make the pump twice as efficient, but I can’t see how it would make it 60 times more efficient than other people can achieve.

Anyway, assuming that it always works at maximum power, the solar bee would pump 1,300,000m3 every year. That’s one 25th of the lake every year. But the [url=http://www.ilec.or.jp/database/oce/doce02.html]International Lake Environment Committee[/url] says that the residence time (the amount of time it takes the lake water to replace itself) is 0.2 years. In other words, the lake replaces its water five times a year (it does have a catchment of 1,865 square kilometres). So, nature turns over the lake water 125 times faster then the solar bee.

We taxpayers are paying $350,000 for this!

chewy14 chewy14 9:10 am 26 Oct 11

Bramina said :

I saw one of these things in the river. Seriously what a joke. From the size of the solar panels (much less than a square metre) which dictates how powerful the pump can be, these things will be circulating perhaps a litre of water a second in a lake of 33 billion litres.

They’d get far more water circulation at a far lower cost if they use a land based pump connected to mains electricity and ran a pipe into the lake.

In other words:

“I have no idea what I’m talking about, I don’t know what these things do and I didn’t even bother to look at their website that was linked to see the specifications for them:”

http://lakes.solarbee.com/products

pajs pajs 9:04 am 26 Oct 11

Bramina said :

I saw one of these things in the river. Seriously what a joke. From the size of the solar panels (much less than a square metre) which dictates how powerful the pump can be, these things will be circulating perhaps a litre of water a second in a lake of 33 billion litres.

They’d get far more water circulation at a far lower cost if they use a land based pump connected to mains electricity and ran a pipe into the lake.

Bramina, the Solarbee’s don’t need much generating capacity because their energy use is low, in part because they don’t need the pump capacity for creating turbulent flows. A key part of the technology is that it involves near-laminar flows, where a volume from depth is drawn up and then spread, gently, in a thin surface layer. The closer you get to laminar flow, the less energy required for the circulation.

Bramina Bramina 10:25 pm 25 Oct 11

I saw one of these things in the river. Seriously what a joke. From the size of the solar panels (much less than a square metre) which dictates how powerful the pump can be, these things will be circulating perhaps a litre of water a second in a lake of 33 billion litres.

They’d get far more water circulation at a far lower cost if they use a land based pump connected to mains electricity and ran a pipe into the lake.

Okwhatever Okwhatever 12:42 pm 25 Oct 11

So many ‘experts’ on this forum! We are very lucky in Canberra that we all know so much about things aren’t we?

peterepete peterepete 12:13 pm 25 Oct 11

Punter said :

Why don’t they just let motor boats run on the lake from time to time? I’m sure that will churn up the algae enough to solve the problem, and it wouldn’t cost the taxpayer as much too.

Jetskis as a community service

Deref Deref 11:14 am 25 Oct 11

nickwest said :

Three hundred and fifty grand for two solar-powered pumps? Instead of importing these things from the USA, couldn’t we ask the experts right on the shore of Lake Burley Griffin? The ANU has no shortage of engineering students, hydrology students, and sustainability students. I’d have loved the opportunity to have worked on something like this when I was at uni, and I’d be willing to bet the uni could do it for a fraction of the price.

Undoubtedly.

They’d probably be hit with a patent suit of some kind though. 🙁

nickwest nickwest 10:15 am 25 Oct 11

Three hundred and fifty grand for two solar-powered pumps? Instead of importing these things from the USA, couldn’t we ask the experts right on the shore of Lake Burley Griffin? The ANU has no shortage of engineering students, hydrology students, and sustainability students. I’d have loved the opportunity to have worked on something like this when I was at uni, and I’d be willing to bet the uni could do it for a fraction of the price.

welkin31 welkin31 9:03 am 29 Sep 11

Is there a website with data history re LBG water quality measurements going back decades ? I have tried google but only come up with pdf reports.

Aeek Aeek 9:40 pm 28 Sep 11

Punter said :

I’m sure the lake is big enough for canoeists and motorboats to co-exist without tangling with each other, it works so well on the roads. I’d love to see the canoe lanes marked around the edge of the lake.

Agreed, bikes and cars mix well – but cars don’t have wakes.

Punter Punter 6:21 pm 28 Sep 11

I’m sure the lake is big enough for canoeists and motorboats to co-exist without tangling with each other, it works so well on the roads. I’d love to see the canoe lanes marked around the edge of the lake.

Deref Deref 7:06 am 28 Sep 11

Bramina said :

Deref said :

Bramina said :

When the wind picks up the lake gets pretty rough. I would imagine that this would cause far more water circulation than a handfull of these solarbees.

Winds only affect the very top layers. I think this is well worth trying.

Actually waves are not just surface phenomena. They extend down several times the distance between waves as I recall.

I’m not a scientist, but I believe you’re only partially right. Wave action does affect water below the surface, but the movement is vertical – the water moves up and back down so there’s little actual mixing. These gadgets are an attempt to de-stratify the water – to mix the oxygen-poor deeper layers with the more oxygen-rich upper layers, reducing the chemical action that makes nutrients available to algae. Neither waves nor (the gods help us) motorboats do that.

Will it work? Damned if I know, but the lake’s a bloody mess and there must be valid studies into whether these devices actually work or not. Shirley the government’s taken account of those studies. Shirley.

aussielyn aussielyn 10:22 pm 27 Sep 11

Gary Rake & NCA should get top marks for trying to fix the problem. I am sure many hours have been spent by his dedicated team working on this problem. It is all transparent what the price is and they should be congratulated on disclosing this. Of course they will be dammed if they do and if they don’t.
They tried and took a risk, good on them. Why are there so negative comments on innovative inventions such as these? If they work what is the problem?

Bramina Bramina 10:11 pm 27 Sep 11

Deref said :

Bramina said :

When the wind picks up the lake gets pretty rough. I would imagine that this would cause far more water circulation than a handfull of these solarbees.

Winds only affect the very top layers. I think this is well worth trying.

Actually waves are not just surface phenomena. They extend down several times the distance between waves as I recall.

That is part of the problem with the lake as I understand it. The water is shallow, especially on the eastern side, so the waves keep stirring up the silt at the bottom, which causes the water to be murky which prevents stabilising bacteria from growing, which in turn leave nutrients for algal blooms. In fact, towards Scrivener dam the water can be quite clear.

Aeek Aeek 9:30 pm 27 Sep 11

Aeek said :

couldn’t

Aeek Aeek 9:29 pm 27 Sep 11

Punter said :

Why don’t they just let motor boats run on the lake from time to time?

because motors turn intelligent people into idiots? That would be the opinion of my canoeing mates when they let water skiers onto the lake. They could resist exceeding the speed limit for the lolz.

chewy14 chewy14 9:29 pm 27 Sep 11

Henry82 said :

It must be so easy to convince the government into buying junk, this and the libraries paying for music downloads are two perfect examples.

Jumped on the database, searched solarbee. first result in journals. “The SPC (SolarBee solar powered water circulation) was unable to alter water quality and nutrient levels in hatchery ponds and thus failed to control P. parvum”.

Wow, with those exhaustive research skills, I’m surprised the government hasn’t hired you as its chief scientist.
You could have global warming solved in weeks.

Punter Punter 8:18 pm 27 Sep 11

Why don’t they just let motor boats run on the lake from time to time? I’m sure that will churn up the algae enough to solve the problem, and it wouldn’t cost the taxpayer as much too.

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