Charles and David Koch have a long history of doing whatever they can to prevent the expansion and growth of the renewable energy industry — particularly with respect to solar power. Their war against renewables — as with any of their campaigns — comes down to protecting their profit margins.

The Kochs’ anti-renewable presence in North Carolina is nothing new, either — but now they’re ramping it up big time. And on Wednesday, Raleigh’s State Legislative Building was Koch Central.

WRAL-TV reports that the Koch brothers’ American Energy Alliance sponsored a roundtable event in opposition to renewable energy programs. It was a Koch-sponsored event moderated by a former Koch lobbyist, organized by a Koch “legislative champion” state representative who’s also an ALEC member, and featuring a panelist from the Koch-linked Institute for Political Economy.

A quick refresher on why the Kochs aren’t too keen on renewables, as reported by WRAL-TV:

Much of the money the Koch family has made has been through petrochemical fuels. According to a Pro-Publica investigation in 2014, the Kochs have used a trade group known as Freedom Partners Chamber of Commerce to funnel money to a long list of conservative nonprofit groups, many of which defend the fossil fuel industry against public policy initiatives favoring renewables.

When you’re made of oil money, you do what you can to block clean energy alternatives.

You don’t want increased consumer choice — even if you claim to be staunch supporters of free market values.

You don’t want research and development of new clean energy technology, even if it means economic growth. And it does: According the the North Carolina Sustainable Energy Association, $2.6 billion has been invested in renewable projects in North Carolina since 2008 — with 75% of that investment going to North Carolina’s most distressed counties, WRAL-TV reports.