WARSAW (Reuters) - Poland is at risk of power shortages this winter according to analysts who say limited available capacity and low river levels could prompt a repeat of this summer when a heatwave prompted the country's first usage limits in decades.
Eastern Europe's biggest economy imposed strict power consumption restrictions in August after soaring temperatures and low water levels in rivers used to cool coal-fired power plants threatened to overload the grid.
"The risk of power shortages occurring this winter is even bigger than in the summer," said Wladyslaw Mielczarski, a professor from the Institute of Electric Power Engineering at the Lodz University of Technology.
"We cannot really count on wind farms since freezing temperatures are rarely accompanied by wind."
Poland had not imposed such limits since the 1980s but experts say there is a risk of further restrictions this winter.
Poland uses up to 26 gigawatts (GW) of power in winter, higher than the summer peak of 22 GW level recorded on August 10.
Although the country has installed capacity of 39 GW, most of it comes from ageing coal-fired power plants and availability has become an issue.
"There were days this summer when from the 39 GW installed, only 23 GW were operating because conventional plants were out of the system due to high temperature," said Arkadiusz Sekscinski from the Polish Wind Energy Association.
"This is the problem in Poland - installed capacity is based on one technology. In Germany or France there are real energy mixes. The issue is not capacity but the diversity of energy sources."
Extremely low water levels in rivers following a drought over the summer adds to the risk of power shortages this winter, some experts say.
"One cannot exclude power shortages in winter due to the still-low water levels, which could lead to problems with cooling the power stations," said Joanna Mackowiak Pandera from the Forum for Energy Analysis.
Poland's limited import capacity is also a problem as Poland is one of the European Union's most isolated power markets.
Poland is able to import just 2 percent of the electricity it consumes despite borders with the Czech Republic and Germany, two major producers, one local energy thinktank estimates.
Capacity is also expected to fall due to power plant maintenance while in coming years the closure of old plants is expected to cut supply further.
That has increased the importance of how Poland controls electricity demand and how it manages its capacity reserves mechanism in which the grid operator pays power generators to keep some capacity available in case of emergencies.
"We do not see a risk of power shortages, but we do see a risk of sufficient capacity reserves," said the head of Poland's energy market regulator URE, Maciej Bando.
"I hope that the lesson from August 10 will be learned. This is the moment to start the reform of system services."
(Reporting by Agnieszka Barteczko; additional reporting by Anna Koper; editing by Michael Kahn and Jason Neely)