[AR] Re: arocket Digest V3 #50
- From: Bill Claybaugh <wclaybaugh2@xxxxxxxxxx>
- To: "arocket@xxxxxxxxxxxxx" <arocket@xxxxxxxxxxxxx>
- Date: Tue, 17 Mar 2015 03:42:51 -0400
The guy who wants to build solar power satellites thinks power can not be
shipped across an ocean.
Really?
Bill
Sent from my iPhone
On Mar 17, 2015, at 2:59 AM, Keith Henson <hkeithhenson@xxxxxxxxx> wrote:
> On Mon, Mar 16, 2015 at 10:08 PM, Jim Davis <jimdavis2@xxxxxxxxxxxxx> wrote:
>>
>> Keith,
>>
>> 1. You seem to be deliberately avoiding the term specific impulse in
>> favor of exhaust velocity. Any particular reason for that?
>
> I just got out of the habit. Done an awful lot of calculation for
> beamed energy and it was less trouble to use exhaust velocity to
> calculate the energy consumption of the engines. Factor of ten is
> within 2%/
>
>> 2. Am I reading that graph on page 2 correctly? If Skylon makes "only" a
>> 100 flights per year the cost to LEO is over $5000/kg?
>
> That's what the graph from RE says. If you build these things at all,
> you need a large space traffic model for them to make sense. Like a
> power satellite construction project.
>
> snip
>
>> From: Ian Woollard <ian.woollard@xxxxxxxxx>
>
> snip
>>
>> Another type of power is peaker plants; those are used when the network
>> needs extra power, and they're often highly inefficient, but they can
>> command more than ten times the price per kilowatt. They run only a small
>> fraction of the time.
>
> In the long run, power satellites should cost less than peaker plants.
> So it makes sense to build out power satellites to peak demand, in
> fact well beyond peak demand. Instead of managing the grid by
> generation, in the future we could manage it by load. Any available
> power between current load and the capacity of the power satellites
> would be diverted into electrolysis plants to make cheap hydrogen. We
> can use the hydrogen and CO2 salvaged out of the air to make synthetic
> hydrocarbons. The energy to make the hydrogen for a bbl of oil is 20
> MWh. The capital cost (based on the Sasol plant in Qatar) is around
> $10/bbl. So one cent power would make $30/bbl synthetic oil, 2 cents
> would make $50/bbl etc.
>
> Solves both the fossil fuel problems.
>
>> From: Bill Claybaugh <wclaybaugh2@xxxxxxxxxx>
>
> (Keith)
>>>
>>> How do you reduce base load? Base load feeds streetlights, domestic
>>> water pumping, sewer pumps, refrigerators and critical infrastructure.
>>> Shut it off at night and some people will get up the next morning knee
>>> deep in sewage.
>>
>> With storage and interconnection:
>> I assume storage is obvious; connecting U-rope with the Arabian
>> peninsula--where the Saudi's and Oman plan to use the oil to build vast
>> solar plants--extends the effective "daylight" period. Ultimately,
>> connecting the future Arab, European, and North American grids will provide
>> more than sufficient supply for the small nighttime load.
>
> The cost for sending power long distance is substantial, around a cent
> per kWh per 1000 km. Plus as others have pointed out, there is no way
> to get it across an ocean.
>
> Keith
>
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