# Exploring the Bioethanol Production Potential of _Miscanthus_ cultivars
## 1 Introduction  
The use of fossil fuels has been crucial to the development of modern civilisation and is an indispensable resource to the global population. However, due to the increasing concerns on energy shortage and environmental pollution, the development of alternative renewable energy has attracted increasing interest worldwide. Bioenergy is energy generated from biological resources and can directly replace fossil fuels in most applications. _Miscanthus_ spp. grass has become a popular bioenergy feedstock in the UK and worldwide due to its high crop yield (8-32 tonne/ha) and high energy output (140-560 GJ/ha) relative to other feedstocks [1]. It has also been cultivated for environmental remediation, such as CO\({}_{2}\) fixation [2] and heavy metal remediation [3]. _Miscanthus_ is a genus of perennial grass native to the upland plateaux of Asia, first documented in Japanese poetry over a thousand years ago [4]. Several other genotypes of _Miscanthus_ have also been identified across Asia and cultivated worldwide for use as an ornamental plant. The first _Miscanthus_ genotype to be introduced in Europe was a sterile hybrid from Yokohama in Japan, brought to Denmark in 1935 by [PERSON] [5]. Laternamed _Miscanthus_\(\times\)_sigganteus_, the grass was a hybrid of the _M. sinensis_ and _M. sacchariforus_ genotypes. _Miscanthus_ is now grown commonly on most continents. It was not until the 1970s that _Miscanthus_ was considered a potential biomass feedstock, particularly _Miscanthus_\(\times\)_sigganteus_, due to its physiological characteristics. In order to assess the potential of the _Miscanthus_ species for biofuel production, especially fermentative bioethanol production, various studies have been carried out to characterise the plant cell wall composition of _Miscanthus_[6; 7], hydrolyse _Miscanthus_ biomass into a fermentable sugar solution [8; 9] and then ferment the feedstock into bioethanol [10; 11]. An analysis of the lignocellulosic composition of 15 _Miscanthus_ genotypes was carried out in 2010, which concluded that the average cellulose, hemicellulose and lignin contents were in the range of 41.2-52.9%, 23.5-33.8% and 7.6-11.5%, respectively [7]. Further study in the group found that a higher holocellulose (cellulose and hemicellulose) to lignin ratio was positively correlated to a potentially higher release of fermentable sugar from _Miscanthus_ biomass and, therefore, a higher potential bioethanol yield [9]. Theoretical analysis indicated that a maximum bioethanol yield of \(\sim\)0.23 g/g dry weight biomass could be obtained by converting the cellulose component to bioethanol via yeast fermentation [10]. In practical terms, a bioethanol yield of up to 0.19 g/g dry weight _Miscanthus_ was achieved using a mild alkali pre-treatment (4% NaOH at 50 \({}^{\circ}\)C) followed by enzymatic hydrolysis and yeast fermentation [11]. Although various _Miscanthus_ species have been analysed for their carbohydrate content, the studies have been heavily focused on _Miscanthus_\(\times\)_sigganteus_ and on the factors such as the location of the crop and cultivation conditions [8; 11]. The composition difference of different cultivars of _Miscanthus_ sp. cultivated at the same location has not yet been reported. Furthermore, most of the reports only selected an early harvest sample and a late harvest sample to compare the sugar composition [12; 13; 14]. As a consequence, the sugar and mineral composition profile of the plant during the harvest is not clear. In Terravesta Ltd., Lincoln, UK, a variety of _Miscanthus_ hybrids and cultivars were cultivated. In this paper, the lignocellulosic compositions of 7 _Miscanthus_ cultivars harvested by Terravesta over the winter season are initially analysed. Then, the hydrolysis of _Miscanthus_ into a fermentable feedstock is carried out. Bioethanol production using the hydrolyses derived from a _Miscanthus_ sample is performed.