Follow Slashdot blog updates by subscribing to our blog RSS feed

 



Forgot your password?
typodupeerror

Comment: Re:Price won't come down (Score 2) 290

by Michael Woodhams (#49608721) Attached to: Tesla's Household Battery: Costs, Prices, and Tradeoffs

So I'm looking at the lithium price and I see that for $64M I can make a plant/mine which will give me $8M/year profit, and ROI of 12.5%. This looks pretty good. Then I consider than some bright spark might come up with an aluminium based battery technology which would make lithium ion batteries obsolete and could be in production 4 years from now. If this were to happen, in four years I've made back just $32M and now have a worthless mine. Therefore I decide not to invest in lithium production until I can get ROI of 20% because of the risk.

It seems to me that lithium is bound to be either overproduced (if new technology comes along) or underproduced (if new technology does not, but investors are wary of building facilities for fear it might.)

Comment: He was also the second Governor of New Zealand (Score 4, Interesting) 33

by Michael Woodhams (#49599863) Attached to: The Pioneer Who Invented the Weather Forecast

He quickly became very unpopular with settlers due to trying to be fair to the Maori. In one notable occasion some colonists invaded Maori land in an attempt to seize it and got massacred. (They were a poorly armed militia and on the other side was Te Rauparaha, who was so scary that to this day his haka is used by the All Blacks to intimidate their opposition.) After an investigation, Fitzroy sided with the Maori.

Comment: The grid needs storage - not battery storage (Score 4, Informative) 329

by Michael Woodhams (#49566827) Attached to: Why Our Antiquated Power Grid Needs Battery Storage

There are many ways to 'store' electricity. Batteries are just one.

I rather like this one, a thermal storage solution. Putting air into and out of bladders under deep water is a very simple method, as is moving water up and down hills. Then there are flywheels and fixed volume compressed air storage. (The air bladders above are fixed pressure compressed air storage.) There other thermal storage possibilities, but getting good round trip efficiency is tricky.

There are non-traditional battery techniques too: flow batteries (liquid electrolytes in tanks, adding storage capacity is as easy as adding tanks full of electrolyte) and molten metal batteries (take the idea of aluminium smelting and make it reversible).

All the non-battery alternatives I can think of work at industrial scale, so if you're looking for a household/small business solution, I think that at least for now batteries are it.

Comment: Re:Managers & HR take note (Score 5, Insightful) 124

by Michael Woodhams (#49557289) Attached to: When Exxon Wanted To Be a Personal Computing Revolutionary

There are three lessons here. One is about arbitrary work requirements, which you've made well.

Second is the problems which arise when vertical integration in your company means that one level's customers are another level's competitors. This conflict of interest is liable to drive away customers. (A company my father worked for many years ago had a similar issue: one branch manufactured and sold refrigeration equipments and spare parts. Another branch maintained and repaired refrigeration equipment, so their competition was the manufacturing branch's customers. The maintenance branch was separated into a new company to avoid this problem.)

Third is when you have a large corporation with an innovative product, that innovative product's potential can easily be crippled by being held hostage to vested interests of other parts of the corporation.

Comment: Re:I Disagree with the Summary (Score 4, Interesting) 342

Someone in the Youtube comments says "The flight profile veers the booster off to the side on purpose so the exhaust from the final burn isn't directed at the barge where it could do damage"

If this was a planned manoeuvre, I'm much happier. Can anyone confirm this statement?

Comment: Re:I Disagree with the Summary (Score 1) 342

I was shocked at how abrupt and extreme the pitch changes were. I think so long as it needs such gross adjustments so close to landing, landings will be unreliable with a significant chance of failure. It is not at all like the tidy landings made by the Grasshopper test vehicle.

Two engineering changes which could make a big difference are lower minimum thrust (so it can approach the landing with lower acceleration) or lateral control rockets (RCS) at the top of the stage.

Comment: Re:Perfect security (Score 1) 460

by Michael Woodhams (#49426117) Attached to: Planes Without Pilots

"... any modern airliner can be specced with options to fly itself from gate to gate on an ordinary day ..."
Can you tell me more about this? My understanding is that taxiing and take off are always performed manually. Unless it surrendered control to a central airport system, I don't see how autotaxi would even be useful, as actions are so dependent on other traffic.

Comment: Re:This guy has a better idea (Score 1) 221

by Michael Woodhams (#49208569) Attached to: New Concept Tire Could Recharge Car Battery

How about using supercapacitors to convert 5 seconds of 60kW into 15 seconds of 20kW (less losses)?

5 seconds of 60kW = 300kJ. Supercapacitor energy densities are in the range 0.5 to 15 W-hour/kg according to Wikipedia. Say 5 Wh/kg, = 18000 J/kg, so you'd only need a few kg of supercapacitor to make this work. The only price I find is US$2.85 per kJ in 2006, putting the cost at around $1000, probably much less now (but there will also be costs beyond just the supercapacitor.)

You could also make this an option - not much point paying $2000 for this capability if the car is going to be in Singapore.

Comment: Re:Why can't they fairly negotiate? (Score 1) 61

I can't tell if you're serious.

The idea of landing a stage on rocket power for reuse has been around for decades (DC-X comes to mind, there may be earlier examples.) As rockets generally launch seaward for safety reasons, that you might want to land one at sea is obvious. The idea of using a ship as a landing platform has also been around for decades. There is nothing that should be patentable in the big idea "landing a rocket on a ship".

Within this general idea, there are bound to be many smaller patentable ideas: e.g. method for automatically securing a rocket to a deck when it could be up to 15m away from the target landing point.

Comment: Re:International waters (Score 3, Informative) 61

Furthermore, that is why rockets launch from the east coast in the first place: if something goes wrong, the flaming debris comes down over the sea.

However, SpaceX are aiming to do a return to launch site for recovering their stage I boosters. (This surprised me - this must use more fuel than land-at-sea, and the mass of that fuel is directly subtracted from your available stage II payload.) The landing at sea is an interim measure while they prove the technology (because of the afore mentioned potential for flaming debris.)

"Pascal is Pascal is Pascal is dog meat." -- M. Devine and P. Larson, Computer Science 340

Working...