I just don't really see this coming close to meeting their funding goal - regardless of the tech. The pledge structure just isn't crowdfunding-friendly I don't think.
Haven't looked at it too closely, but claims like this scream bullshit to me: "They can also augment geothermal heat pumps to reach 200% efficiency!"
Also, they are being misleading at best when calling it a "power plant" and describing it as "a safe, clean system of renewable energy production and storage".
My understanding of flywheel energy storage is that it does indeed work, but is quite expensive to build a storage unit due to the engineering required and the construction quality requirements. Also, they can be quite dangerous (NASA encases theirs in massive protective shrouds in case of a failure which would almost certainly rip the thing apart).