hope to start a PhD in a couple years. I wish you luck. The truth is that there are very few heterodoxical schools out there. UMKC and UMass Amherst a two, there are a few others. However, most schools teach macroeconomics with microeconomic foundations. "Liberals" like Krugman are proud of this fact. Their solutions to environmental issues is to not limit the role of markets, since markets miss massive amounts of information, but to expand the role of markets to places they shouldn't. They generally give very superficial views on things like free trade and ignore the fact that people like David Ricardo and Adam Smith explicitly said that they assumed that factories would NOT go from country to country freely, labor and goods would (which is the opposite of today). They also almost entirely ignore the role that protectionism has played in economic development. The US developed behind the highest industrial tariffs in the world for a century and a half and most every country has developed behind protectionism. If you are interested, read Ha Joon Chang on that.
Also, if you are interested, read the articles at Nakedcapitalism on how Paul Krugman treated heterodoxical economists like James Galbraith in the 1990's and how he treats people like Steve Keen and the MMT school today (notice too how totally off he is on things like how banks and the monetary system works). There's a reason for that stuff.
If you like Marxist/radical economics, check out Michael Hudson, Robin Hahnel, Karl William Kapp, Elinor Ostrom, Michal Kalecki, Ha Joon Chang, Steve Keen, Joan Robinson, James Galbraith, and Joan Martinez Alier. Oh, and Bernie Sanders' top economic advisor, Stephanie Kelton, and her writing on Clinton's supposedly good budget surpluses. Good luck too!