The phrase "widespread blackouts" means that there are power failures happening over a large area, causing electricity to be unavailable in many places at the same time. Full definition
Last year, the subcontinent's annual summer monsoon arrived months late, parching farms and causing widespread blackouts by reducing hydroelectric supplies. (grist.org)
Heading into the summer of 2017, California's energy markets witnessed unprecedented heat waves, resulting in a very high number of calls, which signaled a need for resources that could act quickly to increase energy supply or reduce demand in order to prevent widespread blackouts. (energy-storage.news)
Secretary of Energy Rick Perry has warned of an energy nightmare in which coal and nuclear power plant retirements threaten the resilience of the power grid and risk widespread blackouts. (nrdc.org)