Solarbee installation kicking off in Lake Burley Griffin.

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?

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!

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!

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

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.

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.

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

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

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. 🙁

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.