I can't claim to have a great deal of knowledge about economics, other than to feel sure that our present system is a dangerous one, or to know exactly what sort of economic model Caroline Lucas favours.
However, I believe she has quite nuanced and unpredictable views about the economy and about the EU. This is evidenced in an article she wrote in the Guardian in 2003 www.theguardian.com/politics/2003/sep/16/euro.eu, in which she criticised the introduction of the euro, saying - amongst other things - that:
"It [European monetary union] will contribute to a Europe run to the tune of the free market agenda, a rigid monetarist environment with maximum price stability. A Europe where regulation - to protect the environment, human rights or social provision - is frowned upon as an impediment to free trade....."
I don't know whether she has since changed her mind about that, or whether she has, as Richard Murphy, claims, a poor grasp of economics, but she doesn't seem too complimentary about monetarism in this particular opinion piece.
As for Green policies being "unrealistic", I feel that what is totally irrational, unrealistic and wilfully closed-minded is the conviction that we can continue to exploit and degrade our planet in the name of "growth" without there being a day of reckoning.