Not far from Norway’s North Sea oil rigs, shipbuilders are assembling some of the first ferry boats ever to be powered entirely by batteries. For years, the yard, nestled against the deep-blue sea waters and snow-clad mountains of the country’s deepest fjord, mostly made fuel-guzzling boats for the oil industry. But orders vanished as crude slumped in recent years. Now, like other Norwegian industries, its future prosperity depends on going green.