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Comment: Re:Why just guns? (Score 1) 258

by nojayuk (#47873241) Attached to: Using Wearable Tech To Track Gun Use

The open availability of firearms is a key factor in the US murder rate that is missing from other advanced Western nations which are not in a civil war or otherwise in turmoil. Murder rates for Sweden: 0.3, Australia: 1.1, Germany: 0.8, Switzerland: 0.6, Finland: 1.6, the US: 5.7. From Wikipedia, data from the past few years.

There's also the glorification of violence in US culture, TV and movies, the militarisation of the civilian population programmed to bend the knee to their uniformed overlords, a large ex-military segment of the population with mental problems, the War on Drugs and a lot of other things but firearms are up there as a major factor in the sore-thumb stakes.

Comment: Re:Why just guns? (Score 1) 258

by nojayuk (#47872913) Attached to: Using Wearable Tech To Track Gun Use

I used the word "rate". That does correct for populaton. A quick look on wikipedia shows the 2012 murder rate in the US was 4.7 per 100,000 people, the UK was 1.0 per 100,000. Japan was 0.3 per 100,000 in 2011.

No I don't know why the organisations that report these numbers use 100,000 rather than a round million. Not many countries have less than a million population.

Comment: Re:flywheel (Score 1) 245

by nojayuk (#47808709) Attached to: Power Grids: The Huge Battery Market You Never Knew Existed

As you say battery breakthrough stories are a dime a dozen (a bit like solar cell breakthrough stories -- I'm still waiting for the $1/watt printed solar cells we were promised in a breathless article on Slashdot about eight years ago). Reality is what you can buy off the shelf now, the ticket price, the lifespan in terms of cycles or years in place, disposal costs at end-of-life etc. etc. Glossy brochures are not the same.

Current off-the-shelf static battery tech like NGK's sodium-sulfur units cost about $2 million per MWh, not $200,000 per MWh but they are expected to last for decades. If they ever solve the little "bursting into flames" problem they've been plagued with they might fit a niche as they're a lot smaller than an equivalent flywheel or other storage system for the same capacity. A drop in price to 1/100 of the NGK batteries is probably going to take a while though.

The Dinorwig pumped storage station in Wales (about 8GWh capacity) cost about $1.5 billion to build but it's been operational for forty years now and will probably last another forty years with a maintenance bill of a few hundred million bucks total. A static battery built of Li-ion cells could match the capacity and performance of Dinorwig at much less capital cost but the half-billion bucks worth of cells would need replacing every five years or so.

Comment: Re:Indeed... (Score 2) 130

by nojayuk (#47805551) Attached to: Finland's Nuclear Plant Start Delayed Again

The Olympic Dam copper, uranium and gold mine in south Australia is installing an experimental acid leach facility to process their spoil to extract residual uranium and copper.

"Olympic Dam currently produces close to 4000 tU3O8 per year and around 180,000 tonnes of copper. The planned [acid leach] expansion could lift annual uranium production to around 19,000 tonnes U3O8 and boost annual copper production by up to 515,000 tonnes." (From World Nuclear News)

The uranium market spot price has been depressed for a few years in part due to the "Megatons to Megawatts" project which put a lot of excess Russian weapons-grade uranium into the fuel pipeline, effectively subsidised by the US government as part of its non-proliferation efforts. Now that this project is complete it's expected the minehead price will rise again and mining operations are looking to expand their production now that it is expected to be more profitable in the near future.

Comment: Re:flywheel (Score 1) 245

by nojayuk (#47805159) Attached to: Power Grids: The Huge Battery Market You Never Knew Existed

The Cruachan dam in Scotland was converted from being a regular hydroelectric dam to pumped-storage with a power rating of 440MW and a total capacity of about 8GWh. The other substantial pumped-storage facility in Britain, Dinorwig in Wales (1.6GW peak output, 8GWh total) was purpose-built in the 1970s with its high reservoir in a worked-out slate quarry high in the hills. Note that both Scotland and Wales do not suffer from a lack of water.

Some of the losses in pumped-storage are due to friction in the pipes as the water is pumped up into the high reservoir and also on the trip back down through the turbines to generate electricity. The further apart the two reservoirs are the greater the losses hence the need for good geography to build an efficient pumped storage facility.

Comment: Re:flywheel (Score 4, Interesting) 245

by nojayuk (#47802373) Attached to: Power Grids: The Huge Battery Market You Never Knew Existed

Pumped storage costs about $200 million per GWh of electricity stored to build. It needs specific geography, high and low reservoirs close to each other to reduce losses pumping water uphill over long distances. It also needs a guaranteed supply of water, lots of it and the sunny parts of the US where large amounts of solar power are being generated are distinctly lacking in water to the point of being either deserts or often in drought conditions during the summer. Pumped storage is also lossy, typically about 65% efficient round-trip.

Mass battery technology costs about ten times as much as pumped storage ($2 million per MWh for sodium/sulfur batteries from NGK), flywheels are a bit less but still a lot more than pumped storage. Cheaper methods of energy storage like compressed air tend to be very lossy.

Grid gas, coal and nuclear generators don't need storage as they either run flat out to meet the instantaneous demand and they can throttle back in quieter times. At the moment intermittent wind and solar generators use the grid as free storage but the more intermittent power that is added to the generating mix the more that storage will be needed to deal with peak inputs and debits. Getting wind and solar farm operators to pay for this extra storage probably isn't going to happen, sadly.

Comment: Re:Since nuclear is "too cheap to meter"... (Score 1) 258

by nojayuk (#47798869) Attached to: Feds Want Nuclear Waste Train, But Don't Know Where It Would Go

The taxpayers want cheap electricity which is why coal and gas are the big players in the US electricity generating market at the moment despite the deaths and sickness extracting and burning those fuels involves. The nuclear industry paid the waste disposal levy (about 50 cents per nuclear MWh IIRC) by adding it to the bill the consumers paid for their electricity, sent the money to the US Government which said "Thanks very much for the free money" and didn't hold up their end of the bargain by taking away and properly disposing of the spent fuel as the law requires. This went on for decades, the generators started having to spend money on on-site long-term storage (dry-casking) and went to court to get permission to stop paying the levy too. They've been dancing like crazy (to use your metaphor) while the Government has been playing the part of a gold-digging wallflower.

As for disposal costs Finland is building a hard-rock geological repository for their spent nuclear fuel at the moment. It's basically a long spiralling deep tunnel at Onkalo adjacent to one of their nuclear power plants. Cost of building it and operating it for a century is currently calculated at 818 million Euros, they have 1.4 billion Eu saved already in their waste disposal fund from previous electricity levies and of course that fund will continue to increase over the next century anyway.

Comment: Re:Since nuclear is "too cheap to meter"... (Score 4, Interesting) 258

by nojayuk (#47796955) Attached to: Feds Want Nuclear Waste Train, But Don't Know Where It Would Go

US law requires the US government to collect and deal with spent nuclear fuel as it is regarded as a stategic material. The same law requires the power generating companies to pay a levy to the government per MWh of nuclear electricity generated for this to be done. As I recall they've paid (or rather the consumers have paid) over $30 billion since the levy was introduced.

The power companies are now paying for on-site dry-cask storage of spent fuel since the US government isn't actually doing what they've been paid to do, that is take away the spent fuel and deal with it. They have stopped paying the levy after a court agreed with them and they are using some of those savings to fund the local dry-cask storage they need.

The taxpayers have benefited from over $30 billion of free money gifted to the government by the electricity generating companies, it's not the other way around.

Comment: Re:Thrust also matters. (Score 1) 211

by nojayuk (#47795961) Attached to: Battle of the Heavy Lift Rockets

The thrust to weight ratio of the rocket motor only really matters near the end of a burn when the motor weight becomes a significant part of the total vehicle mass at that time after hundreds of tonnes of fuel and propellant have been expended. It's a good thing to have a lightweight motor but shaving a hundred kilos off the motor mass isn't as important as boosting the Isp by, say, ten seconds as that boost improves the performance all the way through the burn and has a much bigger impact on payload to orbit with given hardware. SpaceX have been working hard to improve Isp, of course -- the Merlin first-stage 1D motors are a lot better than the original flight motors they started their operations with and they now have optimised upper-stage versions of the 1D for vacuum with improved Isp figures.

I know other manufacturers have looked at methane-oxygen engines in the past but not progressed with them. Why they didn't I'm not sure. LOX/RP-1 has a good track record and decades of actual operation to work with (which SpaceX took advantage of), LOX/CH4 is more of a leap in the dark. Building a big LOX/CH4 motor as the first flight item is another big step and obviates the cheap multi-motor Falcon vehicle platform SpaceX have been developing over the past few years.

Comment: Re:Competition is good. (Score 1) 211

by nojayuk (#47795737) Attached to: Battle of the Heavy Lift Rockets

Most new airline designs are slower than 1970s models (and that's not including Concorde and the Tu-144 either), for fuel efficiency reasons. They're much more reliable and safer, can carry more passengers and freight further per tonne of fuel, cheaper to operate and cycle gate-to-gate, cleaner, quieter etc. but not faster.

Comment: No miracles (Score 4, Informative) 211

by nojayuk (#47795071) Attached to: Battle of the Heavy Lift Rockets

There are no miracles in rocket engine design. The RD-180 has pretty much the best performance to be wrung out of a sea-level-to-altitude LOX/RP-1 motor in terms of efficiency. SpaceX is still playing catchup in that area, trading off the lower cost per Merlin motor for a lower Isp from a simpler design.

As for the Raptor the "new" liquid-methane/oxygen fuel mix it will burn has the potential to produce a higher Isp than the current mainstream LOX/RP-1 mix used in motors like the Merlin, the RD-180 etc. but it comes with downsides -- it means a redesign of the rocket structure to support fully cryogenic tankerage (although not requiring the sorts of extreme temps or processing LH needs), launchpad facilities for fuelling and defuelling rockets will need to be revamped, liquid methane is half the density of RP-1 so the tanks and the rocket structure need to be larger and heavier to contain equivalent amounts of fuel and so on.

1 + 1 = 3, for large values of 1.

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