Prospect has been raising the issue of the lack of forward planning in electricity generation for some time.
The union has campaigned to highlight the rapidly-narrowing gap between the amount of electricity the UK needs at maximum demand and the amount that the UK can generate at maximum output. At present this gap could be as low as 1%
Prospect negotiator Richard Hardy said: "As old coal-fired power stations and old nuclear stations are closed, the gap will continue to shrink.
"Today's IME report projects a position in 10 years time where demand will outstrip supply by 50%. The withdrawal of government support for the Peterhead Carbon Capture scheme simply increases the problem.
"Scotland has lost power stations at Peterhead and Cockenzie in recent years. The giant station at Longannet will close in March 2016.
"This leaves Scotland more and more reliant on intermittent wind generation, the two aging nuclear stations at Hunterston and Torness and on imported energy from England.
"As more power stations close in England, the situation if the wind doesn't blow for a protracted period are very serious, particularly during periods of planned closure (called "outages") at the nuclear stations. There are no plans to build any replacement power stations in the short to medium term."
The closure of Longannet, linked to the identified supply problems, exacerbates the potential for problems with what is know as "blackstart".
If the electricity network powers down due to supply problems, it's not possible to simply turn it back on. The system needs to be re-energised in a planned way.
Once Longannet closes there is no tested method for doing this in Scotland and senior officials in the industry are worried that power cuts during a "blackstart" could last for six days, with massive implications for the economy and domestic customers
"We have repeatedly raised the issue of lack of supply and blackstart issues in Scotland with both the Holyrood and Westminster governments. We are very concerned that the market is not delivering the level of investment in supply sources that do not rely on the weather.
"We very much welcome the IME's report and input to the debate," Hardy added.