Households are facing annual gas and electricity bills of €6,000 from early next year if prices keep increasing at the current rate.
That is more than triple the average €1,900 they were paying at the start of 2021.
The warning follows Electric Ireland's latest hike of 26.7% for electricity and 37.5% for gas, which will hit 1.1m customers.
The price rises mean households now face paying an extra €446 a year for electricity and €516 for gas.
It is the semi-state power provider's third hike in five months, with no end in sight. Electric Ireland increased the price of gas by more than 30% and electricity by more than 10% in August, following almost 25% in May, and two increases last year.
It follows a range of price rises in the past week from utility firms, with SSE Airtricity, Community Power, and PrepayPower all hiking rates.
Consumer comparison website Bonkers.ie's Daragh Cassidy said when all increases are taken into account, households are looking at paying over €1,000 extra for their electricity each year and over €1,100 more for their gas compared to January 2021.
“To say these are unprecedented times is an understatement. Price increases of this frequency and this magnitude are clearly unsustainable.
"That shows you the scale of the crisis we’re looking at.
“We’re heading into winter with gas and electricity prices at absolutely astronomical levels. And it could get even worse.
The average gas and electricity bill is now around €4,000. That’s close to the UK price cap of £3,549,” he said.
However, he warned of further bad news for households.
“In the UK, the price cap is forecast to rise to over €6,000 in January.
"Over 70% of our gas comes via the UK so our prices track theirs relatively closely. Indeed, UK gas and electricity has generally been slightly cheaper than Ireland’s in recent years. So that shows you what we could be looking at.”
The European Commission said on Thursday it is looking into options to cap energy prices and cut electricity demand as part of its upcoming proposals to tackle soaring energy costs.
Mechthild Wörsdörfer, deputy director general of the commission’s energy department, told a meeting of the European parliament’s energy committee: “There is work on emergency measures on electricity prices. There might be also something on demand reduction for electricity.”
European Commission chief, Ursula von der Leyen, will outline the commission’s ideas on capping energy prices in a speech on September 14.
Taoiseach Micheál Martin said Ms von der Leyen has confirmed to him that the EU will be making moves to stem the massive price rises.
"That will perhaps be the link between the price of gas and the wider price and the need to do something quickly in respect of that, and then a more structured reform of the market over the next 12 months," he said.
“From a Government perspective, we will use the budget and also, in tandem with the budget, the cost-of-living package to alleviate pressures on households. We also have to look at the impact on businesses in terms of jobs, retention of jobs.
"We will also be launching a demand reduction approach — in other words, energy efficiency all round and all of us will have to see what we can do to reduce our energy consumption."
Nick Charalambous of Cork-based Alpha Wealth said for now there is no end in sight. He said:
“On top of Russia cutting supplies of gas to Europe, the bounce back in global demand for power post-Covid restrictions, and the failure of many energy suppliers, is making the situation ever worse.
"Whilst governments are trying to put measures in place including funding relief measures to help people with energy and petrol bills, and the EU trying to encourage countries to reducing consumption of gas, it doesn’t seem to have any impact so far.”