Catch some wave energy opportunities on Lake Superior

Craig Hill: There is a lot of potential for wave energy around the world, but in Minnesota, the main potential is along Minnesota’s North Shore of Lake Superior. Even with that, the storms are flashy. We see a lot of periods of calm weather, especially in the summer, and then more intense storms during the fall, winter, and spring seasons.

Overall, the average wave height along the north shore is somewhere in the 2-3 feet high range. These still contain a lot of energy! Probably the most important aspect of wave energy on Lake Superior would be a suitable storage solution, which is common across all renewable energy sectors. Perhaps pumped storage hydropower could be a suitable solution along the north shore?

I do think Minnesota offers a unique location for working with marine energy device developers located anywhere in the world. Duluth has a long history of marine industries in its port, so we have the infrastructure needed to fabricate devices and deploy them on Lake Superior. We’ve also shown that the Great Lakes has a suitable wave resource even though it isn’t as large as the ocean’s wave energy potential. We also have the added benefit of testing in freshwater, which slows the corrosion process.

Many of the challenges in Wave Energy Converter (WEC) development right now are in the dynamics and controls world of engineering, and so we offer a test site that minimizes other challenges so developers can focus on problems such as control system testing. So, in general, I don’t think wave energy will soon be a major contributor to our electrical grid in Minnesota, but we offer an attractive location to test devices and contribute towards global growth of the industry.

There are companies in Minnesota developing other technologies for harnessing energy from marine resources, such as Verterra Energy based out of the Twin Cities. They are developing a unique turbine to deploy in rivers around the world.

Craig Hill: We have already shown there is a sizable amount of energy available at times! It is nothing like the oceans of course, but occasionally Lake Superior behaves like an ocean. We’ve used a variety of sources so far to determine how much energy is available. This includes the small buoys like what is shown in the video you saw, but we also rely on data from larger buoys that have been deployed for many years, as well as output from numerical models. A recent graduate student that I worked with, Chase Pheifer, and I just published a paper that quantifies the availability of wave energy across the Great Lakes. 

If the funding is there, then there is no reason we couldn’t pursue deploying a device now! The most important thing up front though is that we have community support for a project, especially if it is going to be something that is mounted to coastal infrastructure in that community. In Lake Superior, we have the added challenge with the potential for ice in the winter, although there are types of WEC technologies that could be deployed and minimize or mitigate the risk that ice would pose for those structures. They wouldn’t produce much energy in the winter if there was ice, but there are ways they would remain protected from being damaged by the immense forces ice causes on structures.

Beyond nearshore or coastal structure integrated WECs, a particular focus in the industry is looking at how to integrate WECs into large observation buoys that monitor our oceans and Great Lakes. We’re also interested in exploring opportunities to deploy buoy-like WECs, called point absorber WECs, out in the middle of Lake Superior. The remote and energetic location in the lake could provide some excellent testing ground for WECs that target distant ocean deployments!

Response from Craig: Unfortunately no, at least not anytime soon in my opinion. Really the issue is that in the small waves common to the many lakes we have around Minnesota, there really isn’t all that much energy available to harness. For example, a windy day on inland lakes around Minnesota might stir up waves that are about 1 foot in height — bigger of course on some of the large inland lakes.

Those one foot waves are probably washing up on the beach every 1-2 seconds. If someone were standing at the end of a dock that was about four feet wide, there is only going to be about 50-100 Watts of power available across the width of that dock. A small wave energy converter might be able to harness 20-30% of that. Solar panels are cheap, especially for a 100W solar panel, so it would be a much smarter decision to rely on a small-scale solar PV or distributed wind turbine system across much of Minnesota. 

The marine energy industry today has a fairly high cost of energy, especially when compared to onshore wind and solar power. For this reason, marine energy technologies such as WECs are focusing on “Blue Industries” that they can contribute power to. Some industries that operate within marine environments have extremely high costs of energy. There are opportunities where locally produced marine energy could offset those high costs while also working to advance the industry towards a more competitive cost of energy.