First of all I want to recall that a brownfield concession is a contractual arrangements whereby "a private entity takes over the management of a state-owned enterprise for a given period during which it also assumes significant investment risk."Secondly, I read an article that may be of your interest and I wanted to let you know of its existance:You can find it here:Short version(summary):Are brownfield concessions poised for a comeback?Long version(Working paper):The rise and fall of nrownfield concessions"Brownfield concessions are becoming more popular now because governments are more aggressively structuring the arrangements to reduce the risks for private partners. In toll road projects, for example, governments are reducing investment risk by providing capital grants or financing guarantees, and reducing demand risk by using shadow tolls or guaranteeing part of the revenue through minimum traffic assurances. The key challenge in using these contracting arrangements is to find ways of maintaining performance incentives for the private partners."As the article states the key is that demand risk is being reduced by providing financial guarantees. Thus brownfield concessions have an enormous opportunity as financial engineering develops.By the way I found this article on the PPIAF (Public Private Infrastructure Advisory Facility)'s website. This is a world Bank agency and its mission is to help eliminate poverty and achieve sustainable development through public-private partnerships in infrastructure.