Again, I'll start.
An area of work that's been identified as useful to do is to have a life-cycle analysis of environmental impacts of open-net pen and closed containment systems. It may be a bit like comparing apples and oranges, but when you're talking about a land-based system, the issue of waste management is a challenge. There are opportunities and there are experiments, or demonstration projects, that are seeking to use the waste as compost in fertilizer and for those types of things. I'm not sure how feasible that is, but that is one possibility that people are looking at.
You're right: waste management is a challenge. It is a challenge in open-net pens as well, but it's a new challenge and a particular challenge for closed containment.
Power use is another issue. One challenge, both in terms of costs and environmental impacts, is that these systems need an enormous amount of power. Challenge number one is that you have to be close to and able to gain access to a power grid, but challenge number two is with GHG emissions and the amount of power you are drawing down for these systems.
That said, we know that the open-net pen processes are not without challenges as well. But power use, greenhouse gases, waste management, resource depletion for concrete structures and the like are all issues. Work is being done, and we're trying to seek some of that information, on a life-cycle analysis. You're right that we need to better understand the environmental impacts of closed containment, in particular. We already have a sense of the challenges around open-net systems.