As the Strait of Hormuz edges towards closure, global energy markets are under strain, with oil and gas flows from the Middle East increasingly restricted. In response, a record number of tankers are heading west to the US coast. But with prices volatile and uncertainty growing, producers are holding back from ramping up output. Sky’s Ed Conway travels to the Permian Basin, the most productive oil field in the United States, where the fracking boom has helped transform the country into an