To clarify, Nuclear energy is considered an "alternative energy source" rather than a "renewable" energy source. It is one of the key differences between the two, as nuclear energy is an alternative but does not necessarily reduce our carbon footprint, it still emits about 16 grams of carbon dioxide-equivalent for each kilowatt-hour of electricity it generates (gCO2e/kWh).. On the other hand, renewable energy sources such as solar and wind power do not require the input of radioactive materials that must still be sourced from the earth. Renewable energy (as conveyed in the name) can be continuously harnessed and does not have the same environmental impacts of alternative energy sources such as Nuclear energy. This is a challenge that designers face today as we are ultimately past the threshold of being able to repair the damage that we have already done to the earth. We can mitigate it by implementing short term systems that simply combat what the predominant threats of climate change are at the moment (e.g. trying to create systems that are net-zero energy or greatly harness the use of renewable energy) but in the long run-- which is hard to say exactly when (another issue)-- we must increase adaptation strategies that can not only continue to mitigate, but also pretty much completely change the way we live. As humans have their own personal agendas, this is the most difficult aspect to change, which, in the end, would involve changes in human attitude towards sustainability and how we go about our daily lives. So overall, maybe he's against Nuclear as he would rather focus on renewable sources that, in the end, have a more promising adaptation strategy.

ps. Im a Sustainable Environmental Design student at UC Berkeley... so this is pretty much what my life revolves around: saving the environment, making everything equitable, yet allowing the economy to thrive! Fun but daunting and semi-impossible :)