Hundred dollars a kg/Note 1 - Revision history

67.188.151.37: /* Rockets */

2009-04-24T16:57:33Z

Rockets

Woozle: formatting, links

2008-09-15T21:58:59Z

formatting, links

← Older revision		Revision as of 21:58, 15 September 2008
Line 14:		Line 14:
	coal-fired capacity in the US is about 300 GW.		coal-fired capacity in the US is about 300 GW.
	Alas, elevator cable strong enough		Alas, elevator cable strong enough
	for a space elevator does not yet exist.		for a [[space elevator]] does not yet exist.

	Rockets		==Rockets==

	We can lift power-satellite parts with		We can lift power-satellite parts with
Line 25:		Line 25:
	analysis. The rocket used in this analysis is here:		analysis. The rocket used in this analysis is here:

	<http://www.ilr.tu~~-berlin.de/koelle/Neptun/NEP2015.pdf>http://www.ilr.t~~-berlin.de/koelle/Neptun/NEP2015.pdf		http://www.ilr.tu-berlin.de/koelle/Neptun/NEP2015.pdf

	The Neptune design is about 3 times the capacity		The Neptune design is about 3 times the capacity
	of a Saturn V, and some of the same people who		of a [[wikipedia:Saturn V\|Saturn V]], and some of the same people who
	designed it designed the Saturn V; i.e., it is solid engineering.		designed it designed the Saturn V; i.e., it is solid engineering.

	This reusable vehicle delivers 350 metric tonnes to LEO, and 100 t to lunar orbit or GEO. To		This reusable vehicle delivers 350 metric tonnes to [[low Earth orbit\|LEO]], and 100 t to lunar orbit or [[geosynchronous orbit\|GEO]]. To
	lift 100 t to GEO Neptune uses 3762 mt of propellant for the first stage, 1,072 mt for the		lift 100 t to GEO Neptune uses 3762 mt of propellant for the first stage, 1,072 mt for the
	second stage, and 249 mt for the third, totaling 5,077 mt.		second stage, and 249 mt for the third, totaling 5,077 mt.

	Space shuttle main engine O2 to H2 ratio is 6 to 1.		Space shuttle main engine O<sub>2</sub> to H<sub>2</sub> ratio is 6 to 1.

	That is, 1 part in 7 of the propellant is liquid		That is, 1 part in 7 of the propellant is liquid

Woozle: NOTE 1 moved to Hundred dollars a kg/Note 1: is specific to that page

2008-09-15T21:47:55Z

NOTE 1 moved to Hundred dollars a kg/Note 1: is specific to that page

← Older revision	Revision as of 21:47, 15 September 2008
(No difference)

Hkhenson: New page: In theory, with a high efficiency device such as a moving-cable space elevator, the electrical energy to lift a kg from the surface of the earth to GEO is only14.75 kWh/kg. That is under ...

2008-09-15T20:30:48Z

New page: In theory, with a high efficiency device such as a moving-cable space elevator, the electrical energy to lift a kg from the surface of the earth to GEO is only14.75 kWh/kg. That is under ...

New page

In theory, with a high efficiency device such as
a moving-cable space elevator, the electrical
energy to lift a kg from the surface of the earth
to GEO is only14.75 kWh/kg. That is under $0.15
at the target price for electric power. This
would pay back the lift energy in about 15 hours
for a 1kg/kW power satellite or 30 hours for a
2kg/kW unit.

400 GW/year production rate for 2kg/kW power sats would require lifting 2,200,000kg/day. Over a
24hr/day is 91,700 kg/hr. Multiplying this by
14.75 kW/kg gives 1.35 GW. For scale, the aircraft carrier
Enterprise produces 0.21 GW, and the installed
coal-fired capacity in the US is about 300 GW.
Alas, elevator cable strong enough
for a space elevator does not yet exist.

Rockets

We can lift power-satellite parts with
rockets. This has been dismissed for decades as
being too costly. The short space elevator
energy payback and an email from a veteran rocket
engineer prompted an energy payback
analysis. The rocket used in this analysis is here:

<http://www.ilr.tu-berlin.de/koelle/Neptun/NEP2015.pdf>http://www.ilr.t-berlin.de/koelle/Neptun/NEP2015.pdf

The Neptune design is about 3 times the capacity
of a Saturn V, and some of the same people who
designed it designed the Saturn V; i.e., it is solid engineering.

This reusable vehicle delivers 350 metric tonnes to LEO, and 100 t to lunar orbit or GEO. To
lift 100 t to GEO Neptune uses 3762 mt of propellant for the first stage, 1,072 mt for the
second stage, and 249 mt for the third, totaling 5,077 mt.

Space shuttle main engine O2 to H2 ratio is 6 to 1.

That is, 1 part in 7 of the propellant is liquid
hydrogen (LH), or about 725 mt of LH. The launch
site would make electrolytic hydrogen out of
water (the only long-term source). That costs
about 50 kWh/kg plus another 15 kWh to liquefy
the H2. Add 5 kWh for liquefying oxygen at 6 x 0.8 kWh/kg.

That would be 70 MWh per mt, or 70 GW hours for
1000 tons, or 50.8 GWh for 725 mt. At a kg/kW,
100 mt of satellite produces 100,000 kW, or 0.1
GW. Thus, it would take 508 hours to pay back
the lift energy or 21.2 days, 42.4 days for
2kg/kW. This does not account for the energy
that goes into structural parts, photovoltaic
cells (or heat engines) and transmitter. The
current energy payback for ground based solar
panels (including supports) is about 3
years. This would drop to a few months in space
because of the higher continuous light on the cells.

Energy cost would be $5.08/kg for fuel. Rocket
efficiency would be 14.75/508 or 2.9%.

The real problem is the cost of aerospace
hardware. The cost of the rocket is estimated in
the above paper at $1.5 billion each, and
maintenance and operations about the same. The
rockets are in theory reusable up to 200
times. If we count on a conservative 100 uses, a
rocket delivers 10 M kg of payload at a cost of
$3000 M or $300 a kg delivered to GEO, three times
above the $100/kg needed for dollar a gallon
fuels. (This does not count RDT&E or the
investment in ground based facilities. For this
traffic model, they should be a small part of the total cost.)

← Older revision		Revision as of 16:57, 24 April 2009
Line 49:		Line 49:
	GW. Thus, it would take 508 hours to pay back		GW. Thus, it would take 508 hours to pay back
	the lift energy or 21.2 days, 42.4 days for		the lift energy or 21.2 days, 42.4 days for
	2kg/kW. This does not account for the energy		2kg/kW, or ~100 days for 5kg/kW. This does not account for the energy
	that goes into structural parts, photovoltaic		that goes into structural parts, photovoltaic
	cells (or heat engines) and transmitter. The		cells (or heat engines) and transmitter. The
Line 58:		Line 58:

	Energy cost would be $5.08/kg for fuel. Rocket		Energy cost would be $5.08/kg for fuel. Rocket
	efficiency would be 14.75/~~508~~ or 2.9%.		efficiency would be 14.75kWh/kg / 508kWh/kg or 2.9%.

	The real problem is the cost of aerospace		The real problem is the cost of aerospace
Line 70:		Line 70:
	above the $100/kg needed for dollar a gallon		above the $100/kg needed for dollar a gallon
	fuels. (This does not count RDT&E or the		fuels. (This does not count RDT&E or the
	investment in ground based facilities. For this		investment in ground based facilities. For this large a
	traffic model, they should be a small part of the total cost.)		traffic model, they should be a small part of the total cost.)