Two of Alice Springs' power stations, which normally run on gas, have been on expensive backup diesel intermittently since November due to a union stoush.
Union workers have refused to reset the stations back to gas in a timely manner, as part of protected industrial action, and stations have been running constantly on diesel since Christmas.
A reset is a normal regular process in a power station.
Electrical Trades Union NT organiser David Hayes said it would cost two to three times more to run the generators on diesel rather than gas, plus extra maintenance costs.
"Which is, we would say, at significant cost to the taxpayer as compared to running on gas," he said.
"We would say there'd be approximately 2 million litres of diesel that has been unnecessarily used whilst we've been bargaining."
Territory Generation did not provide the ABC the cost of diesel or gas.
But in a statement, it said the action at Ron Goodin and Owen Springs power stations would not increase power bills.
Getting people to the table
Mr Hayes said the government was to blame for not meeting the union's demands.
"It's the most inefficient bargaining process I've ever seen," he said.
"We're just dumbfounded about the lack of urgency … to want to get this deal done.
"People don't want to burn fuel unnecessarily.
"We're using bans that we see can have the effect to try and get the right people to the table, but not disrupt the public."
The full package
The unions want a reduction in hours from 37.5 to 36 hours a week, a widespread increase in annual leave from five to six weeks, more staff employed in the ranks and more staff input into management decisions.
The agreements of about 200 employees are in play, of which about 90 per cent are unionised.
Unions have been offered a 2 per cent increase plus backpay, but have declined three days extra leave in the hope they can translate it to an extra 1 per cent pay.
Mr Hayes said the union was seeking an increase above 4 per cent to address cost-of-living pressures.
"We are looking at an overall package that can attract and retain experienced operators or trades people to the NT," he said.
Tables have turned
Former ETU NT organiser and current NT Public Employment Minister, Paul Kirby, said significant ground had been made with a number of key enterprise agreements since the wages policy change in October.
"The Commissioner for Public Employment has informed me we are very deep into negotiations with Territory Generation and we are very close to making an offer to the bargaining unit," he said.
"We thank the union for negotiating and we respect our hardworking Territory Generation staff and the critical role they play in keeping the lights on."
Territory Generation said it respected the union members' right to take protected action.
"We will continue to work with unions in good faith and ensure discussions remain open; and to work with the union to minimise the impacts of the protected industrial action on Territorians' power supplies."
In good faith
A spokeswoman for the NT Office of the Commissioner for Public Employment confirmed union members were taking approved protected industrial action.
"Meetings are scheduled throughout the negotiations by agreement between the parties, which include Territory Generation representatives," the spokeswoman said.
"T-Gen and OCPE will continue to work with the unions in good faith and ensure discussion remain open with the union."
