Yeah we don&#x27;t know what the actual costs will be apart from their claim that its 60% cheaper than pumped-hydro. However, having done some run-of-the-river hydro projects - even a small 1MW mini-hydro (which is basically roughly a pumped hydro in reverse) requires 2 years of civil engineering for the penstock and weir (the water channel). I would imagine that 1-10MW pumped hydro systems would cost and take a lot longer to engineer. Plus pumped hydro is very geography&#x2F;topography specific.<p>I don&#x27;t have hard data - but wouldn&#x27;t engineering a rail system not be as hard, and need less civil engineering work?