Boston Linux & UNIX was originally founded in 1994 as part of The Boston Computer Society. We meet on the third Wednesday of each month at the Massachusetts Institute of Technology, in Building E51.

BLU Discuss list archive

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

[Discuss] Eclipses Re: Great talks last night, however...

On Sat, 22 Jul 2017 20:08:24 -0400, Richard Pieri wrote:
> On 7/22/2017 12:22 PM, Robert Krawitz wrote:
>> 10x?  Battery charging isn't that inefficient -- 85% for lead-acid
>> batteries, for example
>> (
> "Overall, an efficiency level of 85% is often *assumed*."
> Emphasis mine. The rest of that paragraph goes on to explain some of the
> reasons why you can and will get less than this. Also, these are lead
> acid batteries which have longer lifespans than the Li-ion batteries
> Musk is selling, and they will hold to their higher efficiencies for longer.

But it's considerably more than 10% in practice, right?

>> That's the least of the problems.  You have to keep it in orbit, the
>> beam has to keep station (that kind of concentrated beam had better
>> not leak), and a geosync orbit is still eclipsed part of the time.
> At geostationary altitude a station is eclipsed from the sun for only 70
> minutes per day, and this is only when the sun is near the equatorial
> plane. In practice, a geostationary PV station would have ~99.3%
> exposure over the course of a year vs. a ground station which has at
> best ~33% exposure, and that ~99.3% exposure is always "noon" vs. the
> ground station's noon being a fraction of its exposure time.

You still need storage for those blackouts (albeit less), right?

>> Care to discuss what you see as the problems and how to go about
>> addressing them?
> covers them pretty well, and I do agree with the conclusion that SBSP
> isn't worth it in the short term. Putting that much mass into orbit is
> too expensive right now.

The author is quite clear that he simply doesn't see this as being
plausible any time soon.  And no doubt batteries will improve along
the way.
Robert Krawitz                                     <rlk at>

***  MIT Engineers   A Proud Tradition  ***
Member of the League for Programming Freedom  --
Project lead for Gutenprint   --

"Linux doesn't dictate how I work, I dictate how Linux works."
--Eric Crampton

BLU is a member of BostonUserGroups
BLU is a member of BostonUserGroups
We also thank MIT for the use of their facilities.

Valid HTML 4.01! Valid CSS!

Boston Linux & Unix /