Naked Science Forum
Non Life Sciences => Technology => Topic started by: Naked Harry on 16/07/2021 09:21:16
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John got in touch with us to ask:
"I read somewhere that over 50% of energy is wasted between power station and house/business due to heat losses. I recall this as being one reason why it's difficult to run underground high voltage cables. Is it really that much, and how much would it cost to 'fix the problem' and have local generation?
Secondly, how much did the Tesla battery in Australia cost, and would the construction of some of those be cheaper than all the energy wasted (or the cost of subsiding generators to to produce electricity) when there is a surplus (I'm thinking particularly of wind farms)? Does it work as expected?"
A leading question to really sink your teeth into. What do you think?
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I read somewhere that over 50% of energy is wasted between power station and house/business due to heat losses
Then you read something wrong.
Those losses are normally under 10%.
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how much did the Tesla battery in Australia cost
There's a wiki page
https://en.wikipedia.org/wiki/Hornsdale_Power_Reserve
that says
"During 2017 Tesla, Inc. won the contract and built the Hornsdale Power Reserve, for a capital cost of A$90 million".
That's about £48M
Does it work as expected?"
The same wiki page says
When the Heywood interconnector failed for 18 days in January 2020, HPR provided grid support while limiting power prices. This event was the main contributor to Neoen's €30 million ($A46.3 million) operating profit from Australian battery storage in 2020
That's a pretty good return on investment.
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50% of the energy of any fossil fuel cannot be converted into electricity due to the thermodynamic limitations of practical boiler design. Pretty much the same applies to nuclear power.
Transmission losses depend on voltage and distance. The principal supergrid voltage of 400 - 500 kV (varies by country) results in fractions of a percent loss per mile, whilst local distribution at 11 kV can lose 1 - 2 % per mile.
Local generation is capital-intensive and electrically inefficient: 400 kV switchgear needs a lot of space, so "community" generation is usually at 11 kV or below. However if you have a local source of fuel (e.g. farm waste) and can usefully distribute the waste heat rather than blow it off to the atmosphere, it makes economic sense.
The problems associated with underground cables are principally economic. You have to dig a geologically stable trench every inch of the way and cross roads and rivers, and the armored, insulated cable is very expensive, whereas you can sling a cheap bare conductor 400 meters between pylons to do the same job, a bit of earth slip won't break anything, and faultfinding and maintenance are very easy.
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Thermodynamics do not, in principle, limit the efficiency of transmission of power.
In general, a big power station will be more efficient than a small one.
It's also easier to "reuse" the "spare heat" from a big power generator than a small one.
https://en.wikipedia.org/wiki/Cogeneration
Though there's a trade off - it's easier to move that heat about over short distances.
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This may be what the source you where reading too was referring to.
https://www.google.com/amp/s/blog.spiritenergy.co.uk/homeowner/is-electricity-cheaper-at-night%3fhs_amp=true
Exessive capacity without demand.
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It's also easier to "reuse" the "spare heat" from a big power generator than a small one.
That's a sort of oxymoron! Battersea power station used to supply steam and hot water to the flats across the river at Dolphin Square, but multi-megawatt stations generally do not feed many other establishments because of the cost and losses associated with transporting the waste heat over longer distances. Small generators, on the other hand, can be built close to or even in the middle of villages where the supply and demand for heat are balanced. There are many examples in Sweden where the power plant has been integrated into a local community development, surplus electricity is exported efficiently to the grid, and heavy domestic electrical appliances such as washing machines and cookers have a 3-phase spur supply, improving overall efficiency and reducing installation costs.
The steaming pavements of New York had the advantage that the city was being developed along with the gas, and later electricity, grid, so installing steam pipes from big generators was no problem, but the disruption of established British cities for such a project would probably be unacceptable.
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I read somewhere that over 50% of energy is wasted between power station and house/business due to heat losses.
Most of those heat losses are in the power station. For Australia, that means the inefficiencies of burning fossil fuels.
In particular, for the grid-scale battery on the South Australia/Victorian border, the power will mostly come from Victorian brown coal, which is a water-saturated mess. A lot of energy is consumed evaporating the water before the remaining brown coal is dry enough to burn. So the efficiency of fossil fuels in Victoria & South Australia will be even worse than most places in the world (except those burning peat bogs or frozen tar sands in Canada - those are truly atrocious!).
Solar panels on your roof don't suffer losses from long-distance transmission.
- South Australia has lots of land that would be suitable for grid-scale solar - either photo-voltaic or salt storage.
- Photo-voltaic generation is somewhat inefficient due to the efficiency of current mass-produced solar cells, but at least it doesn't produce greenhouse gases while it is generating.
- The salt storage is somewhat inefficient due to storage as heat, but at least it doesn't produce greenhouse gases while it is generating.
- South Australia is also well positioned on the "Roaring 40's" airstream to produce lots of continuous wind energy. It doesn't produce greenhouse gases while it is generating, either.
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but the disruption of established British cities for such a project would probably be unacceptable.
And yet, it has been done.
https://www.vitalenergi.co.uk/our-work/sheffield-city-district-heating/
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True, but note the scale: 19MW of electrical power, heat for 3000 premises - a village within a city. And Sheffield has a reputation for tearing up city streets to install tramways: I suspect the steam pipe was laid alongside a tram track - anything to use steel! I can't think of a gigawatt station (other than Battersea, now an art gallery) that has been similarly used.
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The CHP system was in place before the supertram.
The disruption was a pain in the proverbial, but surely everybody is used to roads getting dug up from time to time?
Wat would be interesting would be do look at the economics of a hydrogen fueled CHP system on a scale suitable for running my house.
You could (for extra credit) compare it with an air-source heat-pump system.
Feel free to make any assumptions you like regarding size of house , weather etc.
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Wat would be interesting would be do look at the economics of a hydrogen fueled CHP system on a scale suitable for running my house.
If you are on mains gas, you already have 60% of what you need, in the boiler. A gas-powered motor-generator would be quieter than a diesel and shouldn't cost much more than £10k for a 20kW machine. If you cook with gas, you might get away with 10 kW or less.
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surely everybody is used to roads getting dug up from time to time?
I often wonder about the true economic cost of road works. If the road isn't actually dangerous, "improvements" are either a complete waste of money (M6 Toll) or allow traffic to increase until it is saturated again (M25). What is he cost per mile to the national economy, of restricting a motorway to 2 lanes at 40 mph whilst "they" replace an undamaged barrier that doesn't meet European standards of ugliness?
Round here "they" enjoy causing almost continuous traffic jams on all the main roads whilst they increase the width of the cycle path (but never prosecute cyclists for riding on the carriageway) , or pour concrete over the countryside so that empty buses can break down in the middle of a field. Not that it matters, because the "plan" is based on a Very Expensive Computer Model (reality is too cheap to consider) and somebody's brother in law has a contract.
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never prosecute cyclists for riding on the carriageway
Daniel Cadden was famously prosecuted for cycling on the road instead of the cycle path in Telford. His conviction was overturned on appeal on the minor technicality that he had been found guilty of breaking a law that doesn't exist.
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Wat would be interesting would be do look at the economics of a hydrogen fueled CHP system on a scale suitable for running my house.
Small generators pretty much always suck balls for more than occasional use. They're noisy, inefficient, unreliable and high maintenance. There are very good reasons why we have electric grids and have large centralised power stations.
You could (for extra credit) compare it with an air-source heat-pump system.
Feel free to make any assumptions you like regarding size of house , weather etc.
Air source heat-pumps typically cost less to run. Installation cost often tends to be high though.
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What is he cost per mile to the national economy, of restricting a motorway to 2 lanes at 40 mph whilst "they" replace an undamaged barrier that doesn't meet European standards of ugliness?
Zero; because it doesn't happen.
but never prosecute cyclists for riding on the carriageway
As has been pointed out, there's a good reason for that.
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but never prosecute cyclists for riding on the carriageway
As has been pointed out, there's a good reason for that.
It just saddens me that the more public money that gets wasted on cycle paths, the more irate motorists will get, the more road rage there will be against us cyclists who don't use them, and the sooner the pressure for the government to make them compulsory will become irresistible. Then we'll all have to use them, like it or not.
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What is he cost per mile to the national economy, of restricting a motorway to 2 lanes at 40 mph whilst "they" replace an undamaged barrier that doesn't meet European standards of ugliness?
Zero; because it doesn't happen.
www.roadtraffic-technology.com/features/feature67206/ When did they start putting concrete barriers on motorways?
This became policy by the Highways Agency in 2005 when its Interim Advice Note 60/05 (IAN 60/05) called for the use of rigid concrete safety barriers for motorway central reserves where annual average daily traffic (AADT) exceeds 25,000 vehicles a day.
Fascinating. An average of 1040 vehicles per hour means that the road must be pretty safe. The peak flow will be at least 5 times the average, so they will be passing at 60 - 70 mph without serious incident every day - precisely the kind of road that does not need a new barrier!
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What is he cost per mile to the national economy, of restricting a motorway to 2 lanes at 40 mph whilst "they" replace an undamaged barrier that doesn't meet European standards of ugliness?
Zero; because it doesn't happen.
www.roadtraffic-technology.com/features/feature67206/ When did they start putting concrete barriers on motorways?
This became policy by the Highways Agency in 2005 when its Interim Advice Note 60/05 (IAN 60/05) called for the use of rigid concrete safety barriers for motorway central reserves where annual average daily traffic (AADT) exceeds 25,000 vehicles a day.
Fascinating. An average of 1040 vehicles per hour means that the road must be pretty safe. The peak flow will be at least 5 times the average, so they will be passing at 60 - 70 mph without serious incident every day - precisely the kind of road that does not need a new barrier!
You failed to address my point.
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Fascinating. An average of 1040 vehicles per hour means that the road must be pretty safe. The peak flow will be at least 5 times the average, so they will be passing at 60 - 70 mph without serious incident every day - precisely the kind of road that does not need a new barrier!
By this "logic" we should put a barrier on the roads which are derelict and have no traffic at all.
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Not sure I follow. The Highways Agency "logic" is to retrofit concrete barriers on roads with significant rapid traffic, regardless of accident rates. In doing so they need to close a lane and restrict the speed of traffic in other lanes. My question is, quite simply, if it ain't busted, why fix it, if fixing it means causing congestion and possibly (usually) increasing the accident rate in the constricted area. Listen to Radio 2 any rush hour to see how much fun they cause!
The other stroke of genius has been to "widen" motorways by turning the hard shoulder into a running lane and instituting a "smart" motorway system. Once again, the works involve closing the left-hand lane and squeezing the traffic into one or two lanes with a 50 mph limit for months at a time (the new carriageway isn't just a layer of asphalt on the hard shoulder - it all has to be dug out and built to full carriageway standard, plus a whole load of monitoring and warning equipment). When the job is done we have the intriguing spectacle of HGVs running at 60 mph on the new track until they hit some poor bugger who has stopped with a problem because there is nowhere else to go. Not just me but the AA and RAC have pointed out that "smart" motorways are dumb.
The best barrier solution I have seen was to plant wild roses and brambles in the central reservation. Unlike wires, which ping the wandering vehicle back into the traffic lane, or concrete blocks which destroy it, thorn bushes are an excellent energy absorber, a great habitat for small wildlife, and don't reflect or destroy the vehicle. Maintenance is a doddle: run a hedge trimmer along the lane a couple of times a year, and the barrier gets stronger.
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if it ain't busted, why fix it,
People die in accidents, so the mechanisms for the prevention of accidents are busted.
Removing the hard shoulder is, as you say, dim. But it's not a lot to do with your original point.
In this weather, thorn bushes are combustible but...
un a hedge trimmer along the lane a couple of times a year,
and watch the thorns puncture tires while the very same energy absorbing brushwood you created is now on the road.
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People die in accidents, so the mechanisms for the prevention of accidents are busted.
Agreed, but whilst speed cameras are installed on the basis of accident statistics, modifying central reservation barriers appears to be done on the basis of safety statistics: an average of 25,000 vehicles passing a point every day implies that the road is safe!
Rose and bramble thorns don't puncture car tyres, and I'd hope that the contractors would sweep up after them, as they do on minor roads (the dangerous ones!). Interesting statistic: the strategic road network (motorways and major A roads) accounts for only 2.4% of UK road space but carries 33% of the traffic.
Back to electrical transmission losses, anyone?
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Not sure I follow. The Highways Agency "logic" is to retrofit concrete barriers on roads with significant rapid traffic, regardless of accident rates. In doing so they need to close a lane and restrict the speed of traffic in other lanes. My question is, quite simply, if it ain't busted, why fix it, if fixing it means causing congestion and possibly (usually) increasing the accident rate in the constricted area.
Accidents that happen when everyone is going in the same direction can be bad, but they are as nothing to what happens when a car leaves a carriageway and ends up going into traffic travelling the other way. The concrete dividers are designed to bounce the cars back into their own lane, and generally have better outcomes.
Without a concrete divider, if a car does end up entering the opposite lane, if the traffic rate is low, then the chances of a nasty accident is much lower anyway. So you only replace them on the high flow rate roads where the relatively expensive equipment does the most good.
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The other stroke of genius has been to "widen" motorways by turning the hard shoulder into a running lane and instituting a "smart" motorway system. Once again, the works involve closing the left-hand lane and squeezing the traffic into one or two lanes with a 50 mph limit for months at a time (the new carriageway isn't just a layer of asphalt on the hard shoulder - it all has to be dug out and built to full carriageway standard, plus a whole load of monitoring and warning equipment). When the job is done we have the intriguing spectacle of HGVs running at 60 mph on the new track until they hit some poor bugger who has stopped with a problem because there is nowhere else to go. Not just me but the AA and RAC have pointed out that "smart" motorways are dumb.
Smart motorways are safer:
https://www.bbc.co.uk/sounds/play/p09kxjnc
(From 8 mins)
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The best barrier solution I have seen was to plant wild roses and brambles in the central reservation. Unlike wires, which ping the wandering vehicle back into the traffic lane, or concrete blocks which destroy it, thorn bushes are an excellent energy absorber, a great habitat for small wildlife, and don't reflect or destroy the vehicle. Maintenance is a doddle: run a hedge trimmer along the lane a couple of times a year, and the barrier gets stronger.
There's a hedge here. It did absolutely nothing to stop a lorry embedding itself in that thatched cottage.
https://goo.gl/maps/hSqRSahXgfGvximx7
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Depends on distance, quality of transmission devices, how much of transmission system is high voltage vs. lower outlet voltage like 120 volt. Line loss can be much higher but it really depends on the specific power system involved be it High voltage or low and quality of the system, connections, transformers etc. Remember, there is power loss even if no one is using the power as transmission, source, connections, even weather and temperature all have an effect on power transmission and loss.