Bioenergy and biofuels are key to meeting renewable energy and carbon reduction targets. Life Cycle Assessment (LCA) techniques are being used, with varying success and consistency, to help determine the sustainability of the current fuels and pathways selected. In order to meet our longer term targets and pursue long term sustainability emerging processes and systems need to be examined, as well as existing processes. Designers recognise that a large percentage of impacts and costs are pre-ordained within the design stage; so it makes sense to use LCA at the start of the research process in order to minimise these. Determining impacts at this stage could also help select the most promising options with maximum sustainability/GHG reduction potential. At the same time policy makers are beginning to use LCA as a tool to help inform policy choices for future energy pathways. Never the less, there are various uncertainties involved with its use at early stage research level, and also the expansion of LCA to look at wider consequences of the use of a particular product or system. LCA is changing from a traditional, retrospective tool to a more dynamic, forward thinking tool. Whilst this brings a multitude of benefits in terms of ability to predict impacts and minimise these in advance, this method of LCA use is not without uncertainties and difficulties. This paper explores why LCA is important within the bioenergy context and highlights some of the benefits, disadvantages, and changes that are seen through its use.