Nov 05, 2016 03:22 Breakthrough Initiatives Posted on: Breakthrough Initiatives

RE:
"Aug 28, 2016 08:55Markus HlusiakPosted on: Breakthrough Initiatives
In this discussion it is important to distinguish between POWER and ENERGY requirements.
ENERGY is no problem at all. A single launch would need about 20 GWh of electricity, which can be sourced for a couple of million dollars from just about any currently used electricity source (PV, wind, hydro, coal, gas, nuclear all cost about 0.1 $/kWh – give or take half an order of magnitude).
POWER is totally different. All electricity generating technologies mentioned above cost around 1000 $/kW to build, so setting up a dedicated system and then using it only once for 10 minutes is obviously a bit pricey (100 billion dollars). 100 GW is somewhere in the range of a tenth of the combined electricity generation of North America and Europe. Even if you distributed all lasers over a whole hemisphere of Earth you couldn’t just flick a switch and get those 100 GW without significantly affecting the power grid. Even if this were not the problem, the cost of drawing 100 GW from a high voltage AC supply system seems prohibitive. Transforming power down to the few volts DC needed for the lasers would cost somewhere around 100 $/kW, or 10 billion dollars in total. So obviously some kind of storage is needed. And to keep the cost of having to transmit 100 GW as low as possible it should be very close to the lasers. If the system was designed to be charged within a week external power supply needs reduce to 100 MW, which seems manageable. At this level, the only near-team feasible options seem to be high-power batteries and supercaps. Current prices for Li, as mentioned by Philip and Karen, are 100 $/kWh or 10 $/kW. Last time I checked supercaps were around 10 000 $/kWh, which would mean around 1700 $/W in the case of a 10 min launch. This still leaves us with a multi-billion dollar bill, which might be stretching the budget. The only hope I see is a strongly integrated modular option with laser diodes and caps/batteries in close proximity, preferably on the same chip or at least on the same voltage level. I don’t think that anything that can’t be miniaturized would be an option, e.g. flywheels, MHD, superconducting magnets, pumped hydro etc."

Answer:
We agree with your analysis. We looked at it a little different when it came to super caps. We thought they are basically a thin sheet of graphene and a dielectric. These materials are very cheap. If we were to produce a large quantity of these we think we could drive the price down to the pennies a KW. I also think our power needs may less 20 GWhr depending on how lucky we are. 100GW laser power 200 GW wall plug power for 2 min is more like 7 GWh which effectively equals 20 GWh depending on your assumptions.

- Avi Loeb, Breakthrough Starshot

Nov 05, 2016 03:23 Breakthrough Initiatives Posted on: Breakthrough Initiatives

RE:
"Aug 31, 2016 09:54michael.million@sky.comPosted on: Centauri Dreams
'The only hope I see is a strongly integrated modular option with laser diodes and caps/batteries in close proximity, preferably on the same chip or at least on the same voltage level. I don’t think that anything that can’t be miniaturised would be an option, e.g. flywheels, MHD, superconducting magnets, pumped hydro etc.' MHD’s are very powerful, powers 100's of MW per cubic meter and therefore can be made very compact! they are not to be ignored and there is room for much improvement. http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19760066328.pdf";

Answer:
Great idea. We wish we could find a supplier of a magnetohydrodynamic generator that could be cost competitive to gas or coal power plants. The current state of the industry is gas fired plants are at about $0.07 kw/hr that is really tough to beat. Although I am concerned about the byproducts of combustion and just having that much methane around for the gas fired power plants. It turns out that when hit with 1064 laser light the CH4 may glow. This is something we need to investigate.

- Avi Loeb, Breakthrough Starshot

Nov 05, 2016 03:24 Breakthrough Initiatives Posted on: Breakthrough Initiatives

RE:
"Sep 11, 2016 05:57michael.million@sky.comPosted on: Centauri Dreams
What is also interesting is that once we get into space we can use variable short UV and X-ray FEL's with their narrow emissions and wide emission wavelength variations to resolve the Doppler/reflectivity issue for dielectric mirrors or prisms and allow for a much longer powered phase. They are large and heavy but will allow much greater energy and accelerations to produce much higher velocities. If they are packed in a multi barrel design for X-ray configurations it would allow electron recycling over the whole system substantially improving efficiencies...but first little steps.

http://xfel.desy.de/localfsExplorer_read?currentPath=/afs/desy.de/group/xfel/wof/EPT/TDR/XFEL-TDR-final.pdf On Earth we have an opportunity to use the visible part of the spectrum to just inside the UV part of the spectrum which has more energy than in the infrared part of the spectrum, for instance UV 0.4 micron would have around 3.5 times the energy of a 1.5 micron window and the atmosphere is more transparent over a larger range, so it could be better."

RE:
"Oct 23, 2016 07:57michael.million@sky.comPosted on: Centauri Dreams
We could make the MHD unit very compact and powerful if we say used one rocket chamber and turbine set and then a series of nozzles leading from it each into a channel. The superconducting magnets are then arranged in a torus shape between each channel which would fully contain the magnetic field reducing stray field losses and reduce the distance over which the magnetic field has to jump a channel. The MHD conducting plates could also be made thermionic which could emit charged particles just through heating, this could be achieved by having a vacuum space at the back of the channel plate where the charged particles can jump to the polished collector plate. Now if we had the cryogenic fuel running over the collector plates before it gets pumped into rocket motor it would improve the design efficiency significantly by reducing heat losses and improve charged particle collection. By combining thermionic and MHD concepts into the package the overall design would become quite efficient. http://phys.org/news/2016-03-scientists-thermionic-energy-conversion-efficient.html And http://www.nanowerk.com/spotlight/spotid=39283.php";

Answer:
These are great ideas. The only problem is that we cannot go out and buy a MHD today. The execution risk is considered high.

- Avi Loeb, Breakthrough Starshot

Nov 18, 2016 11:32 michael.million@sky.com Posted on: Centauri Dreams

"These are great ideas. The only problem is that we cannot go out and buy a MHD today. The execution risk is considered high.

- Avi Loeb, Breakthrough Starshot"

We may have to put something on the shelf as well by investing in MHD's technologies as topping units, and they can be improved much more. By using MHD's in combination with fuel cells and turbine sets we can use the extra efficiency to reduce our carbon footprint significantly world wide and get our power for 'Starshot'. Governments will need to start getting an effective method to reduce carbon/pollution emissions and MHD topping allows this, -perhaps governmental and 'starshot' partnership MHD grants could be a way forwards. Our power plant will most likely need liq H and O as the fuel with a potassium seed material.

Dec 06, 2016 18:14 Breakthrough Initiatives Posted on: Breakthrough Initiatives

RE:
"Nov 18, 2016 11:32 michael.million@sky.com Posted on: Centauri Dreams

We may have to put something on the shelf as well by investing in MHD's technologies as topping units, and they can be improved much more. By using MHD's in combination with fuel cells and turbine sets we can use the extra efficiency to reduce our carbon footprint significantly world wide and get our power for 'Starshot'. Governments will need to start getting an effective method to reduce carbon/pollution emissions and MHD topping allows this, -perhaps governmental and 'starshot' partnership MHD grants could be a way forwards. Our power plant will most likely need liq H and O as the fuel with a potassium seed material."

Answer:
If and when MHDs become available we will certainly make maximum use of them.

- Avi Loeb, Breakthrough Starshot

Dec 07, 2016 08:25 michael.million@sky.com Posted on: Centauri Dreams

MHD's have been built but never followed through effectively, we could also put up with a poor efficiency of using just the MHD's (20-30)% during the initial stages. Although the first stages of the power system will be less efficient we will have plenty of power to send many probes to the solar focus lines to look for targets which would use a lot less energy. Once we get more finance we can add the other lasers, turbines, fuel cells, thermionic systems etc. later to make it more efficient.

http://www.nextbigfuture.com/2011/07/russian-and-other-work-on-mhd-nuclear.html

Dec 16, 2016 08:20 michael.million@sky.com Posted on: Centauri Dreams

MHD's have the advantage of been stackable, can be configured to generate high voltages for easy transmission and can be staged. If we say had a number of MHD's in a circle with a toroidal super conductor magnet system we could at the end of each MHD channel add another MHD or branch of MHD's where the output of the first feds heat through a heat exchanger to pre-heat the fuel/oxy mixture before it is pumped into the next MHD rocket chamber and so on. In a setup like this we are not limited to the size of the power generation, we could just add on MHD/toroid magnet units into the Terawatt region and beyond.

Dec 16, 2016 17:37 jens.fr.knudsen@gmail.com Posted on: Centauri Dreams

If I get this right, isn't the magnitude of the power requirement about the same as Dr Gerald P Jackson envisages for his antimatter factory (~40GW)? http://www.antimatterdrive.org/index.htm Maybe there is more than one use for a facility like this.

Dec 18, 2016 16:14 michael.million@sky.com Posted on: Centauri Dreams

"If I get this right, isn't the magnitude of the power requirement about the same as Dr Gerald P Jackson envisages for his antimatter factory (~40GW)? http://www.antimatterdrive.org/index.htm Maybe there is more than one use for a facility like this."

Yes it could aid an antimatter factory, it could also be used for asteroid defence, if we accelerate a sail say with a deuterium package at high enough velocity it will undergo fusion and release a large amount of energy on impact. It could also much later be used to send out materials that could be used in a pellet runway system to supply a much larger probe/ship with fuel without it having to carry it.

Jan 05, 2017 02:41 Breakthrough Initiatives Posted on: Breakthrough Initiatives

RE:
"Dec 07, 2016 08:25 michael.million@sky.com Posted on: Centauri Dreams
MHD's have been built but never followed through effectively, we could also put up with a poor efficiency of using just the MHD's (20-30)% during the initial stages. Although the first stages of the power system will be less efficient we will have plenty of power to send many probes to the solar focus lines to look for targets which would use a lot less energy. Once we get more finance we can add the other lasers, turbines, fuel cells, thermionic systems etc. later to make it more efficient."
&
"Dec 16, 2016 08:20 michael.million@sky.com Posted on: Centauri Dreams
MHD's have the advantage of been stackable, can be configured to generate high voltages for easy transmission and can be staged. If we say had a number of MHD's in a circle with a toroidal super conductor magnet system we could at the end of each MHD channel add another MHD or branch of MHD's where the output of the first feds heat through a heat exchanger to pre-heat the fuel/oxy mixture before it is pumped into the next MHD rocket chamber and so on. In a setup like this we are not limited to the size of the power generation, we could just add on MHD/toroid magnet units into the Terawatt region and beyond."

Answer:
Thanks for your help. It is possible to use the MDH to generate power but difficult to understand at this point if it is the most cost effective and efficient approach. A detailed trade of all the options will be considered.

- Pete Klupar, Breakthrough Starshot