Hi, here in the UK some companies do offer half hour prices. However these are published in advance and for residential customers capped a 35p/kWh. Standard cost is 15p/kWh. Customers on these tarrifs eg octopus agile can on occasion also be paid to consume power!
My experience of big industry is different, prices are half hourly however the power company can notify you of likely peak demand and thus spot prices. To counter this, companies predict when this will happen ( 5pm to 6pm on dark freezing days) and either stop/limit production and switch to backup power for the duration. We had diesel pumps to replace electric. Jet turbine generator units and gas fed boilers to run steam turbines to generate power. The consumption and generation was shown in real time to avoid errors.
