The potential of grasses, including Lolium species, for energy is limited because plant varieties have not been selected for this purpose. Genetics and breeding are necessary, to increase yield, provide resistance to disease and improve nutrient and water use efficiencies as for other uses. However there are also distinct challenges to determine and improve quality traits to increase the value and conversion efficiency of grasses as energy feedstocks. Perennial grasses offer the potential to be utilised through either thermal or biological conversion methods. The route chosen being largely determined by the calorific value, moisture content and the ratio of soluble to structural carbohydrates. However which ever way grasses are used the major determinates of energy content are lignins, cell wall (cross linking) phenolics and the soluble and cell wall carbohydrates. In addition to energy content, these components also have the potential to affect the efficiency of the energy conversion process and the end quality of some liquid fuels. Fuel specification is therefore a critical area and to assist in this, it is necessary to develop high throughput methods for phenotyping of for example the cell wall components. Infrared spectroscopy methods have therefore been developed to link phenotype, as determined by wet chemistry or infrared spectroscopy techniques, to genotype.