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Comment Re:Temperature chart? (Score 1) 117

Yeah, I seem to be getting tripped up on the difference between gravimetric energy density and power density.

The abstract says an "energy density up to 20 Wh/kg, power density up to 20 kW/kg".

Do you have any suggestions on relating that power density quantity to other battery types?

I get 2-3kWh out of my 90lb 155Ah 12VDC AGM/SLA batteries sipping at a 60hr rate. But that battery is about 41kg, so what do they mean by 20 kW/kg?
Shouldn't I get 41kg/battery * 20kW/kg = 1800kW/battery? Reducing that to 1.8MW doesn't seem realistic. What's the right way to think about this?

Comment Re:Temperature chart? (Score 1) 117

Hrm, yes. In the abstract, it says "energy density up to 20 Wh/kg, power density up to 20 kW/kg". (

I suppose I'm getting tripped up on the difference between "energy density" and "power density".

I use VmaxTanks SLR155 AGM/SLA 155Ah 12VDC batteries (
These weigh 90lbs (40.9kg) and can store 2.1kWh of energy. (2.1kWh)/(40.9kg) = 51.3Wh/kg, which is about what you said.

So, you're right. 20Wh/kg FnCu < 51.3Wh/kg PbS. The difference in units between "energy density" and "power density" appears to be time.

How would you relate the gravimetric power density of 20kW/kg of the proposed battery cells to that VmaxTanks battery?

Or, what is the distinction between gravimetric energy density and power density?

Comment Temperature chart? (Score 2) 117

I'm curious how these cells perform in cold weather conditions.

I use 12VDC lead-acid SLA batteries on a mountain top for a wireless repeater but those are like 0.05kw/kg and $280-300/ea. Getting heavy batteries up the mountain can be extremely challenging (think snowshoes uphill in 5-6ft of snow carrying a 100lb replacement battery). I'm also at the 49th parallel so winter peak solar is like 3 hours/day and you need a large buffer in case it is effectively zero hours of solar for days in a row while keeping your radios up 24/7.

Something like this would be great for me since it's something like 1500x more energy dense by weight... That is, if it can survive cold weather, or with a heater it is still an effective alternative.

Submission + - SPAM: Napthlalene-derived carbon nanospheres for room temperature quantum computing

synaptic writes: In the journal Nature, scientists report the novel synthesis of carbon nanospheres from napthalene pyrolysis allowing room-temperature quantum computing. From the article:

"We have demonstrated that a long conduction electron spin lifetime in metallic-like material made up of carbon nanospheres can be achieved at room temperature. This material was produced simply by burning naphthalene, the active ingredient in mothballs. The material is produced as a solid powder and handled in air. It can then be dispersed in ethanol and water solvents, or deposited directly onto a surface like glass. As the material was remarkably homogeneous, the measurements could be made on the bulk solid powder. This allowed us to achieve a new record electron spin lifetime of 175 nanoseconds at room temperature. This might not sound like a long time, but it exceeds the prerequisite for applications in quantum computing and is about 100 times longer than that found in graphene."

Link to Original Source

Submission + - SPAM: India's Al Gore: HAARP Caused Global Warming

schwit1 writes: “The US has developed a type of weapon called High Frequency Active Auroral Research Programme (HAARP). It strikes the upper atmosphere with a focussed and steerable electromagnetic beam,” Anil Madhav Dave, India’s Environmental Minister, told Business Standard Monday. “HAARP is an advanced model of a super powerful ionospheric heater which may cause the globe to warm and have global warming effect.”

India is the world’s fastest growing, and third largest, emitter of carbon dioxide (CO2). In 2014, India got 59 percent of its electricity from coal, and Indian leaders are ramping up the country’s coal production by opening a new mine every month. The country appears set to literally double down on coal by doubling production and building 87,122 megawatts of new coal power capacity. Even with that level of coal use, it is estimated that 400 million Indians, 31 percent of the population, lack access to electricity.

Link to Original Source

Submission + - SPAM: First image released from MeerKAT radio telescope

schwit1 writes: Even operating at a quarter of its eventual capacity, South Africa's MeerKAT radio telescope showed off its phenomenal power Saturday, revealing 1,300 galaxies in a tiny corner of the universe where only 70 were known before.

The image released Saturday was the first from MeerKAT, where 16 dishes were formally commissioned the same day.

MeerKAT's full contingent of 64 receptors will be integrated next year into a multi-nation Square Kilometer Array (SKA) which is is set to become the world's most powerful radio telescope.

Link to Original Source

Submission + - New Study Shows Why Big Pharma Hates Medical Marijuana writes: Christopher Ingraham writes in the Washington Post that a new study shows that painkiller abuse and overdose are significantly lower in states with medical marijuana laws and that when medical marijuana is available, pain patients are increasingly choosing pot over powerful and deadly prescription narcotics. The researchers found that, in the 17 states with a medical-marijuana law in place by 2013, prescriptions for painkillers and other classes of drugs fell sharply compared with states that did not have a medical-marijuana law. The drops were quite significant: In medical-marijuana states, the average doctor prescribed 265 fewer doses of antidepressants each year, 486 fewer doses of seizure medication, 541 fewer anti-nausea doses and 562 fewer doses of anti-anxiety medication. But most strikingly, the typical physician in a medical-marijuana state prescribed 1,826 fewer doses of painkillers in a given year. As a sanity check, the Bradfords ran a similar analysis on drug categories that pot typically is not recommended for — blood thinners, anti-viral drugs and antibiotics. And on those drugs, they found no changes in prescribing patterns after the passage of marijuana laws.

The tanking numbers for painkiller prescriptions in medical marijuana states are likely to cause some concern among pharmaceutical companies. These painkiller drug companies have long been at the forefront of opposition to marijuana reform, funding research by anti-pot academics and funneling dollars to groups, such as the Community Anti-Drug Coalitions of America, that oppose marijuana legalization. Cost-savings alone are not a sufficient justification for implementing a medical-marijuana program. The bottom line is better health, and the Bradfords' research shows promising evidence that medical-marijuana users are finding plant-based relief for conditions that otherwise would have required a pill to treat. "Our findings and existing clinical literature imply that patients respond to medical marijuana legislation as if there are clinical benefits to the drug, which adds to the growing body of evidence suggesting that the Schedule 1 status of marijuana is outdated."

Comment Re:Gay crew members scrapped in TNG... (Score 1) 354

There were the genderless J'naii in The Outcast (ST:TNG 05x17) who Riker pressured into sexual relations.

Captain Janeway in Voyager was widely believed to be a lesbian, despite her marriage.

Tasha Yar on TNG always talked about the rape gangs but held a position as chief security officer and was widely believed to be a lesbian or at least bi-sexual (and willing to get it on with fully-functional androids).

In ST:TNG 01x14 "Angel One", the Enterprise sends an away team to a female dominated planet. They take great pleasure in feminizing and dominating Riker and all of the men in that society are made to be feminine (by Earth standards).

Comment Space (Score 1) 91

This fits nicely with Blue Origin. It's one thing to get to space but you're going to need habitats and biospheres and other large scale structures once you get there. Bezos has talked about moving industrial activities off Earth along with mining asteroids.

I suspect they will learn a thing or two about building these structures on Earth that will be applicable to the longer-term goals of the space-faring Bezos.

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