You cannot grow the economy without increasing energy use. For environment and to reduce global warming need to reuse and recycle and use sustainable materials, yet the boost for economy promotes buy and throw.
Economist always promote growth, which grows energy use. Further economist is one science which assume a lot how the world works versus in other sciences that have to measure how the world works.
I would say that Keynesian economics and the environment is not coherent. In the sense that Keynesian economics lowers the interest rate in an artificial way, which promotes economic growth. This economic growth increases consumption.