That is rather contradictory. In one sentence they say the 2 x...

That is rather contradictory. In one sentence they say the 2 x 125 MW turbines will ' take full advantage of market volatility' while in the very next ' Project size remains flexible to changes as Genex proceeds towards financial close.'

If the first was true then the second shouldn't be possible. I deduce that they don't know/can't accurately model the size of the arbitrage market opportunity or can accurately model the market opportunity and is at or below 250MW.

This reduction is size will mean significantly lower NPV and IRR metrics. Reducing size will hardly reduce capital cost, but significantly reduce output.

Costs that stay the same or marginally change;
1) Power transmission lines (massive cost for 150km+ of lines....)
2) Substation(s)
3) Eldridge pit civil works
4) Wises pit civil works
5) Design, consult, financing fees and operations
6) Down pipe diameter and drilling costs
7) Relief pipe and drilling costs
8) Access shaft
9) Pump room size

This is very bad for project economics. It may still get up but almost certainly will require some significant form of government financial support. I'm calling it, this needs government financial support.

It may be a sales pitch, but it's also a pitch on how bankers/investors can get a return on their money. What just happened results in a marginally lower capital cost and significantly lower output. Ouch.