Amazon got the biggest headlines for its drone delivery plans, but it's an idea that's catching on across the shipping industry. At a nautical trade fair in Hamburg this week, the shipping research firm DNV GL revealed designs for a new electric vessel that would ferry cargo with zero crew members — roughly the nautical equivalent of Amazon's automated delivery drones. Dubbed "ReVolt," the concept ship is designed for short sea voyages, carrying up to 100 standard TEU containers at a relatively slow 6 knots. But because the ReVolt has no crew, it doesn't need living quarters or safety equipment, resulting in a much more efficient trip between ports.

It's still just a concept vessel, but vessels like the ReVolt could make a huge difference in how we move goods around the world. More than 9 billion tons of cargo moved through ports in 2012, leaving a huge market if automated vessels like the ReVolt are adopted. According to DNV GL, there will be real benefits for firms who do. Because of low maintenance costs, the company estimates the ReVolt would save more than a million dollars a year compared with shipping the same goods on conventional diesel ships.