Sign up | Login with →

Comments by Keith Henson Subscribe

On Power Satellite Progress

October 5, 2014    View Comment    

On Power Satellite Progress

"Can you explain the reasoning behind that number?"


You can find the formula for the levelized cost of electrcity here;

I am assuming $1,600,000 per MW as the initial cost and 10% per year of the cost for maintenance.  Power satellites run supplying base load, here I assume ~91% of the time; it may be higher.

The discount rate is 6.8%, same as the government uses for other sources.  It's put into a spreadsheet here:

The ratio between the $1600/kW cost and the cost that comes out of the formula (~2 cents per kWh) is close enough to 80,000 to one.  Electric power cost is proportional to the cost of a power satellite (or any power source that has no fuel cost) in this ratio for this discount rate and years of service.

If you use the UK government discount rate of 3.5%, then the cost of power is just over 1.5 cents per kWh and the ratio is ~100,000 to one.

October 5, 2014    View Comment    

On Power Satellite Progress

Roger, right on there being a technical dimension.  At the moment I am stuck on the cost and mass of the VASIMR engines needed for the LEO to GEO transfer.

Otherwise, I agree with you about the reasons it is unlikely for the US to do power satellites.  At the moment, the UK is ahead because they are building Skylon.  Japan would like to do virtually anything that doesn't need nuclear reactors.

And, as you mention, China.

October 5, 2014    View Comment    

On Power Satellite Progress

Before you talk about a "1 kw system," you should read the Wikipedia article on space-based solar power and see why 5 GW is the minimum size for a 2.45 GHz microwave power link.

October 5, 2014    View Comment    

On Power Satellite Progress

Roger, the allowable cost for a power satellite is $1.6 B to $2.4 B per GW.  That gives 2-3 cent per kWh power.  The mass of one is 25-30,000 tonnes.  They come in 5 GW lumps, so the cost is $8-12 B each.

Re getting it down, mass in GEO is useful.  Old power satellites can be reprocessed into new ones when and if they ware out.  There are problems with space junk, but they are in getting parts to GEO, not satellites at GEO.  I have an analysis, if you want I can put it up as a google doc.

People have talked about reflecting sunlight on earth based solar farms.  There are problems because the sun is not a point source.  I happen to be interested in solving the big problems, not little stuff involving the ISS.

October 5, 2014    View Comment    

On Power Satellite Progress

Sorry, Roger, I wasn't clear on that point.

2021 is when production at a delivery rate of one a month starts.

2023 just falls out of the financial spreadsheet since there have been enough flights to build up the mass of the first power satellite plus the infrastructure in GEO.

I should send you the spreadsheet.

September 11, 2014    View Comment    

On Why We Need CCS, Part 2: Reactive Climate Change Mitigation

The carbon problem is mostly an energy economics problem because coal is such a cheap way to make electricity, on the order of half the projected end point of solar (zero cost for the PV surface).

So if you want something to displace coal without opposition, it needs to be less expensive.  If you want it to take over in a hurry, then it needs to be much less expensive.

If you can figure out a way to get the cost to lift solar power satellite parts to GEO down to where it is perhaps a third of the total cost, then they clearly win in the energy market.

Cheap enough electric power will also solve the transport fuels problem.  Once cent per kWh power will make $30/bbl synthetic oil, two cent will make $50/bbl.  (Straight forward chemistry and existing plants in the billion dollar class).

So one way to solve the carbon and climate problem (to whatever extent carbon contributes) is to reduce the cost to $100/kg or less for lifting million of tons of power satellite parts to GEO.



May 9, 2014    View Comment    

On Dollar a Gallon Gasoline

Since the 70s, it's always been the case that the microwave intensitiy is less than sunlight.  Birds.

The reason is makes sense is that the amount of energy collected over a year is much higher, the rectenna converts at around 85% as opposed to what you can get from PV, and the thing works 24/7 insteat of about 1/5 of the time for PV.  The rectenna structure is a lot lighter too.  Being mostly open space, you don't have to brace it much against wind.

It's worth reading the Wikipedia article.

April 29, 2014    View Comment    

On Dollar a Gallon Gasoline

JP, have you considered electric power tractors?  Or big trucks?  Or locomotives?  Or jet aircraft?  How about ships?

Or for that matter, the cost of replacing the entire fleet of hydrocarbon powered vehicles.

Not saying we should not switch to electric vehicles, just that it has consequeces far beyond running down to the store for a loaf of bread.


April 9, 2014    View Comment    

On Dollar a Gallon Gasoline

Robert, try here

It's an orbit that uses the earth's equitorial bulge to precess as fast as the earth goes around the sun.

April 9, 2014    View Comment    

On Dollar a Gallon Gasoline

Royce, that's not much of an argument.  Earth's shadow eclipses GEO power satellites less than one percent of the time.  And it happens spring and fall when the power demands are so small that the grid can shift power an hour east or west to cover the outages.

Cost is the determing factor.  With the lift cost reduced to $100/kg, I make a case for power satellites cheap enough to displace coal, 2 cents per kWh, and I can go through all the steps to justify that cost.  What cost do you get for the Sun-synchronous orbit?

I can't make a case for existing launch vehicles even if the tranmission was free.

April 9, 2014    View Comment    

On Dollar a Gallon Gasoline

Roger, part of the problem is how seriously do we take the buildup of CO2 in the atmosphere? 

Is that more or less important than military surpemacy?

There is also the point that the need to defend mid east oil supplies will go down if synthetic oil is seen on the horizon.

Another factor is that a propulsion laser can only see about 1/3 of the earth at a time.  For example, if the Chinese and Indians built one, the optimal place for the propulsion laser is over about longitude 130.  From there, in GEO, you can't see any of the continental US, and even Hawaii is an extreme slant.

I like your ideas re multiple people being able to cut them off.  Perhaps using a signal that is required for them to opperate at all.  To avoid accidental shutdown, perhaps the loss of two out of 7 signals would turn it off.

April 6, 2014    View Comment