The price per KW of SPS : A brief economic guestimate

>>>>>Here in Australia we pay at home between 8 c / kwh ( all currency is
in
Australian $ ) and 25 c / kwh depending on where we live and the usage
of the electricity. This cost covers the generation of the power, and
the construction and maintenance of the Power lines. For the SPS I would
suggest aiming the market not at the consumer but at the current
electricity suppliers. by this I mean sell the electricity from the
Rectenna station direct to the Companies that look after the Power lines
and current Power Stations. I suggest this for two reasons, One is
demand is continually outstripping supply, and secondly there are older
stations that are going to need replacement on a regular basis.>>>>>

The cost of installing 1 kwe gas-fired power capacity is approximately
$US1000. A typical 1GWe gas-fired station would cost about $1billion.
Nuclear stations can cost considerably more, ranging from US$1000-2500/KWe,
depending the circumstances (e.g. environmental law-suits, sudden changes
in station design, e.t.c) The cost per/Kw for Nuclear can eventually drop
to very low levels, i.e. 1.81c/Kwhr in the US, for 1999. This is due to the
fact that once original construction costs are paid off, the running costs
of nuclear are quite low. Rising fossil-fuel costs recently made nuclear
power the cheapest energy option in the US.

>>>>>SPS will always be more expensive than terrestrial energy, at least in
terms of short term retail cost.
Where SPS scores is the lowest long term clean up cost of any system.>>>>>>

From an economic point of view, SPS is similar in many ways to nuclear
power. You have large initial construction costs, but no fuel requirements
and very little maintenance. If we aim for $1/watt of installed capacity on
the space-side of the construction, the cost of an SPS would come out at
about $100/kg. This is based on O'Neills estimate that a 10GWe SPS would
weigh in at 100,000 tonnes. With modern solar power technology, we may be
able to improve upon this.

Materials cost for the SPS can probably be taken to be around $10/Kg for
raw unprocessed lunar imported regolith, during the early days of space
manufacturing. We can base this upon a very rough guestimate:

We shall assume that a solar powered mass driver is used to deliver the
raw regolith to a collection point at L1 or L2. The solar panels are
sun-tracking, and the entire power system weighs in at about 4Kg/m2. This
gives a specific power of 34w/kg, night/day average, on the lunar surface.
No power storage is assumed. Lets assume that we decide to give our base a
100MWe solar power system. The Solar panels would weigh about 3000 tonnes,
mass driver(100 tonnes), small lunar base (50 tonnes), mining equipment (50
tonnes), processing facilities (50tonnes) and crew (100t over 5 years).
That's a total of 3350 tonnes. At a delivery cost of 2500$/Kg (with BDB's)
the total base cost comes to $8.375 billion in launch costs to the moon.
With administration and mission control costs, lets make that a round 10
billion. Toss in another $5billion in development costs and you have a $15
billion base cost, over a period of 5 years.

How much material can we launch during 5 years? lets make two more
assumptions. The mass driver is 60% efficient and 5Mwe is used in mining
and processing (ie, production of fibre-glass bags). Escape velocity of the
moon is 2370 m/s. A 1 Kg mass would require a launch kinetic energy of
2.81MJ in order to escape from the moon. So in five years the total amount
of material export is: (95Mw x 0.6 x 3600 x 24 x 365.25 x 5)/2808450 =
3,202,448,326 kg. The unit cost of material is 15 billion/3202448326
= $4.68/Kg.

Factor in the cost of the catcher at L2, and the amount of material that
must be wasted as reaction mass in the mass driver tugs and $10/Kg
delivered to the SMF is a good estimate. (NOTE:This is the materials cost
assuming that total payback within 5 years of all lunar base operations is
required)

A cost of $10/Kg is far too expensive for us to think about building
anything like island-1, within the first few years at least. But it is
cheap enough to allow us to build SPS satellites economically, from a raw
materials point of view. $10/Kg is roughly 100 times cheaper than the cost
of lifting the equivalent mass to HEO from Earth.

It should be noted that after 5 years the only fufther costs will be those
associated with maintaining the lunar base. Solar panels and mass driver
parts that are manufactured in HEO, could be delivered to the lunar base at
a cost that is several times lower than that associated with shipping them
up from Earth. After five or six years, the materials costs needed in order
to construct the 4 million ton island-one habitat, should fall to around
$10 billion. Construction costs would be considerably more than this. Under
optimistic conditions, island one construction costs might come to 10 times
more than materials costs, or $100 billion. This puts it within O'Neills
original estimates. If were to locate an SPS at L2 and manufacture a
rectena on the moon from native aluminium, iron and ceramics, the cost per
unit of power on the moon, could drop considerably. Lunar materials costs
in HEO, are likely to be directly proportional to the cost of power on the
moon.

Tony

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