On the back of what Orion has provided in terms of estimated value of the significant of today's announcement, here is a nice little graph for anyone else wishing to form their own rough guestimates..
https://www.aer.gov.au/wholesale-markets/wholesale-statistics/sttm-quarterly-prices
It shows the quarterly
wholesale spot prices per gigajoule with Sydney in June peaking at $10.5/gigajoule. 2017 average for Sydney, Brisbane and Adelaide is well above $9/GJ.
So I'd say Orions estimate at $30,000/day is somewhat well on conservative side. Could be anywhere in the range of $30, 000 - 50,000/day ( ~$11m - $18m a year respectively).
These are just some quick back of the hand calcs whilst im at work so correct me if I wrong.