Electricity is increasingly priced by when it is used. For decades the question about a home was how much energy it used, but with solar panels, batteries and electric cars homes can also generate, store and sell power. Since June 2026 Ireland's largest suppliers have had to offer tariffs that change every half hour. In the UK, households pay around 26p per unit they buy, while solar owners may be paid only a few pence per unit they sell. Running laundry, dishwashers or car charging outside the evening peak, when demand and prices are high, can cut bills.

In 1909 D. W. Griffith made a 14-minute film about a speculator who corners the wheat market and doubles the price of bread. A farmer sows his field while a 'Wheat King' gambles in the Chicago wheat pit; bakers raise the loaf from five cents to ten and the poor line up for bread. Griffith cut back and forth between the farm, the feast and the breadline, a technique called parallel editing, so audiences saw both ends of the economy at once. The film drew on Frank Norris's stories and on a real scheme: months earlier Chicago financier James Patten had cornered wheat, sent bread prices up and made about $5 million, roughly $185 million today.