PrefaceIn our first paper, UN-Energy focused on "The Energy Challenge for Achieving the Millennium Development Goals." We pointed out that available energy services fail to meet the needs of the world's poor, with 2.4 billion people relying on traditional biomass for their energy needs and 1.6 billion not having any access to electricity. The basic commitments to poor people cannot be met without a far more focused approach to energy services.At the same time, awareness has grown across the world of the impact of human energy consumption on our environment, and specifically on our global and regional climate. Whatever the optimal energy mix, it is clear that nations face tough choices in their approach to sources of energy.It is no surprise, then, that global interest in bionenergy has grown rapidly in recent years. From being merely an interest of marginal innovators, it has become a multi- billion dollar business - transforming economies - thanks to rising attention and support from governments and the public. What could be more appealing than home-grown energy, essentially created by sun-and-water-fuelled photosynthesis, with new jobs and development opportunities to be tapped?Yet, nothing human or ecological is straightforward. And so it is with biofuels, perhaps particularly liquid biofuels. Will biofuels push out food crops, raise food prices, and exacerbate food security? Will biofuels create unexpected negative rather than positive external environmental effects? Could biofuels even exacerbate the impact on climate when the entire production chain is taken into account? How will increased investment in biofuels affect trade patterns? What would a sustainable approach to bionenergy look like? These questions need to be addressed.In this latest publication, UN-energy seeks to structure the approach to the current discussion on bionenergy. "Sustainable Bioenergy: A framework for Decision-Makers" is the contribution of the UN system to the issues that need further attention, analysis, and valuation, so that appropriate trade-offs can be made and both the energy needs of people met and the local and global environment adequately protected. We hope that development partnerships at the country level as well as the management of global issues will be helped by our articulation of the issues.UN-Energy is collaborative framework for all UN bodies that contribute to energy solutions. It was born out of the 2002 World Summit on sustainable Development (WSSD) in Johannesburg, South Africa. Based on the Summit's outcomes and action plan, it brings together the top-level energy managers of the UN system in a modest, collective approach to inform analysis, inspire dialogue, and ultimately promote action by governments, energy stakeholders, and multilateral organizations. We do not replace inter-governmental policy dialogue. Nor can we match the resources of private sector and civil society....Appropriate trade-offs can be made and both the energy needs of people met and the local and global environment adequatly protected.However, rooted in the multilateral frameworks of Millennium summit, Financing for Development, the WSSD, and the World Summit of 2005, we hope to use the collective strength of the UN system to effect change.This paper was sponsored by the food and Agriculture Organization (FAO), drawing on important support from the Worldwatch Institute in creating the document. Many members of UN-Energy have contributed actively. We are grateful to all and in particular to the Vice Chair of UN-Energy, Gustavo Best of FAO. In the spirit of our chosen method of work, this is a joint product. We hope that you will find it inspirational reading.Mats KarlssonMATS KARLSSONCHAIR, UN-ENERGYAPRIL 2007