Cuba's power grid failed Sunday, causing another nationwide blackout, a state utility said in a social media post. As the lights suddenly turned off across Havana, residents who were sitting outside to get some respite from the summer heat audibly groaned en masse. Cuba has been suffering rolling power cuts due to ageing equipment and a US energy embargo that halted regular deliveries of fuel for power stations. This is just the latest in a series of total collapses of the electricity grid. The power cuts have made normal life almost impossible, with each outage also meaning that water supplies trickle away and ceiling fans slow to a halt.