Never, if only $5 million is available. Once a process is proven in the lab, development of a working protoype takes a lot of engineering. The rule of thumb is that this takes at least 10 times as much as research. We estimate currently that at least $20-30 million over three years would be needed to build a prototype. (Think about 5 minutes worth of the US military spending) Once mass-production is begun ( which costs more initially in investment) costs per unit should drop to about $300,000 for a 5 MW generator.