Wells Fargo & Co is angling to cash in on the US energy boom, as the fourth-largest US bank looks for new avenues of revenue growth to overcome a slump in mortgage lending, its traditional driver of profits.The bank is increasingly looking for lending, investment banking and investing opportunities in the oil and gas sector. It says it now employs the largest staff of petroleum engineers of any US bank. And unlike many of its other divisions, which are primarily focused on the US market, Wells Fargo's energy business has expanded internationally to places such as Aberdeen in Scotland and Calgary, Canada. "We have the biggest and most-focused business in that space," said chief financial officer John Shrewsberry in an interview. He said Wells Fargo has 400 employees dedicated to serving energy companies.Shrewsberry said the bank finances companies across the energy sector. These include companies specializing in exploration and production, those that own and operate pipelines and barges, and those that refine and process oil and natural gas. Wells also says it is now the top underwriter of high-yield bonds and syndicated loans for oil and gas companies.