Reply To: Global Warming

[asymmetric_implosion]

Brian H wrote: a_s;
“probably thermal cycle (same old same old).” Not a watt, unless you count such possible applications as heating nearby buildings with warm air, etc. The ancillary equipment to extract heat and convert it to electricity is not a) present, b) economic, or c) usable with the low-grade (low-temp) output of the FoFu.

As for the photovoltaic “inefficiency”, examine the “onion” design. It has perhaps thousands of layers/stages to extract a very high percentage of the X-ray energy.

And as with Z-pinches, sacrificing wires or metal cylinders or pellets etc. with every shot is, IMO, a complexity bridge way too far for continuous output. Murphy’s power grows exponentially with number of components.

Low temp? I’ve seen numbers of 1000C floating around this site. That is a pretty good temperature for a thermal cycle with modest efficiency (~40%). I’ve looked at the onion. It will absorb x-rays but how much will turn into useful electrons? That is where the efficiency typically comes in. You can absorb 100% of the sunlight but only about 10% is converted to useful electrons. X-rays may convert more efficiently as they are well above the band gap but you are still limited on efficiency. I hope it is greater than 40%. I know heat will be generated by a FoFu power plant so the question is why not use it? Turbines on the 5 MW scale are small and efficient. A helium turbine in particular is very compact and efficient. It adds more electrons to the grid. Some cooling is going to be required of FoFu-1 so why not put that heat to good use rather than dump it into the air needlessly.

Z-pinches: I’m not saying that MAGLIF will ever be a viable power plant. I don’t think NIF is viable either. I’m simply saying that NIF and MAGLIF will reach breakeven. It will be a demonstration and nothing more. FoFu will demonstrate Q>1 well before a power plant is built if economically feasible. Using best guesses for numbers, NIF is producing something like 10 kJ of fusion energy per shot (DD) using 4 MJ of laser energy (I believe the bank is 400 MJ with 1% conversion to photons). MAGLIF will use 20 MJ of pulse power to get something like 10 kJ of fusion energy in the near term. FoFu uses more like 56 kJ to get ~1J of DD. So the math suggests that NIF has a physics Q of 0.0025, MAGLIF will couple no more than 33% of the stored energy to the load so MAGLIF is 0.015 and FoFu using the same 33% coupling to the pinch as MAGLIF has a Q of 5.4E-5. If all things were equal MAGLIF would get there first but NIF has more funding and they are running “bad loads” right now to test the models. When they get serious later this year I expect they will get to Q=0.5 pretty quickly (yes, physics Q). Q=0.5 puts NIF on par with JET which has demonstrated a Q=0.7 some time ago. MAGLIF will suffer from something like 10 shots per year so unless the models are spot on, it will take some time. FoFu, the smallest project with the least funding, will come in third on this list. One can argue with the exact numbers but they should be order of magnitude correct. Resources are likely to shape the results and NIF has the most resources by far. The first gate will be the physics Q>1 followed by the engineering Q>1. FoFu has the most straightforward road to get from physics Q>1 to engineering Q>1. NIF and MAGLIF have some serious hurdles after they show physics Q>1. The big question is whether a plasma focus (a two stage Z-pinch) can be made to show Q>1. I look forward to the answer over the next year or so.