[AR] Re: arocket Digest V3 #50
- From: Keith Henson <hkeithhenson@xxxxxxxxx>
- To: arocket@xxxxxxxxxxxxx
- Date: Mon, 16 Mar 2015 23:59:35 -0700
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
Other related posts: