Extreme space weather could knock out power grids on Earth costing the USA more than £32.5 billion ($40 billion) in a single day, Cambridge researchers have warned.

Power networks on Earth can be affected by so-called Coronal Mass Ejections in space, which see billions of tonnes of hot gas thrown out of the sun and affect geomagnetic fields on Earth.

Electrical engineering experts are divided over the possible severity of blackouts caused by such an event.

A study led by university academics has examined the potential cost of such blackouts, looking at the total incurred in a single day for four different blackout footprints within the USA.

The cost would include loss of power at factories, with production grinding to a halt, offices without use of computers and the wider supply chain impact outside a blackout zone.

Manufacturing would be the US economic sector most affected by a solar-induced blackout, followed by government, finance and insurance, and property.

Outside of America, China would be most affected by the indirect cost of such US blackouts, followed by Canada and Mexico - as "these countries provide a greater proportion of raw materials, and intermediate goods and services, used in production by US firms".

Study co-author Edward Oughton, of the Cambridge Centre for Risk Studies at the Cambridge Judge Business School, said researchers focused on the daily cost of a power outage as there was much debate over how long it would take to restore power after a solar storm-induced blackout.

The paper is published in Space Weather , a journal of the American Geophysical Union.

Its most extreme blackout scenario, affecting 66 per cent of the US population, found the daily domestic economic loss could total £33.7 billion plus an additional £5.6 billion loss through the international supply chain.