'Unstable' renewable energy sources increase the risk of 'supra-regional' electricity blackouts with multi-billion pound consequences, insurance giant Allianz has warned.
Solar panels and wind turbines are a "volatile" source of power with fluctuations in the electricity supply risking "grid instabilities" and triggering wide-scale blackouts.
Ageing infrastructure and increasingly cross-border electricity networks have heightened the likelihood of a devastating collapse of power supplies lasting months and covering several continents, according to the joint report by Allianz and the Chief Risk Officer Forum.
In eastern Germany, turbines in strong wind can produce more than all German coal and gas plants put together, while the need to switch off turbines in high winds causes a drop-off in electricity of 12GW - equal to two nuclear power plants. Outages are likely if there is too little demand or storage capacity to accommodate the jumps in supply.
Leading risk analysts modelled a worst-case scenario in which transformers are knocked out in the United States, causing outages to cascade through the grid into Canada, Russia and Scandanavia.
Credit cards and cash machines would stop immediately, and petrol pumps and refineries would shut-down within six hours. Back-up generators powering hospitals, stock exchanges, emergency services and sewerage plants could run out of fuel within days.
Industry would grind to a halt, cooling equipment would fail and homes would go without food supplies, water or heating, leaving families spending winter around open fires. Allianz predict it would take a year to get the transformers back online. The cost to insurers would top one trillion dollars and chronic power shortages would continue for up to a decade.
"Blackouts during the last ten years in Europe and Northern America have demonstrated an increasing likelihood of supra-national blackouts with accompanying large economic losses," the analysts wrote.
"Traditional scenarios only assume black-outs for a few days and losses seem to be moderate, but if we are considering longer lasting blackouts... the impacts on society and economy might be significant," the report said.
Outages could also be trigged by cyber attacks, terrorist action, natural disasters or solar storms - eruptions of charged particles from the surface of the sun which can distort magnetic fields and destroy electricity transmission lines. One such storm knocked out power for six million Canadians in 1989, with the next forecast for 2012.
Half of new electricity capacity worldwide comes from renewable sources such as wind farms, solar panels and biomass plants - up from just 8pc in 2009.
The report said privatisation of electricity networks had split power generating companies from distributors, removing incentives to invest in and maintain infrastructure - a problem exaccerbated by placing windfarms in remote areas. EU nations need to spend £20-25bn on new grid infrastructure by 2016.
The report highlighted how the failure of back-up generators at the Fukushima plant after the Japanese earthquake caused a Chernobyl-scale radiation leak and closed down 11pc of Japan's power supply, leaving factories idle and shrinking GDP by 3pc.
A blackout in the US and Canada in 2003, when the failure of one Ohio generating plant knocked out more than 100 others, left 50 million people without four days and cost £3-5bn.