**6. Biofuel from biomass and biofiber**

In general, sugar substrates from tropical biomass and biofiber are potential sources for biofuel production such as ethanol and butanol because they are abundant, cheap, and renewable [85]. Biomass and biofiber utilization will reduce the dependency on fossil fuel and at the same time it could help in reducing toxic gases emission with an abundant feedstock that can support for a very long period of time. This second generation biofuel does not compete with human food resources which are non-edible in nature [86]. In lignocellulosic biomass conversion for biofuels such as ethanol and butanol, pretreatment plays a major role in separating the major components (lignin, cellulose, and hemicellulose) of the biomass. The conventional chemical and enzymatic pretreatment methods have disadvantages such as producing byproducts and low conversion of biomass components [86]. Numerous numbers of publications reported the potential of bioenergy from biomass wastes through irradiation pretreatment [43, 45, 62, 87, 88]. Most of the studies agreed that irradiation pretreatment could assist the reduction of particle size that provide better access for subsequent process. This pretreatment clearly proved able to enhance enzymatic saccharification and fermentation performance.

Presently, Malaysia is dependent on fossil fuels such as coils, oil, and natural gas as well as renewable energy sources such as hydro, biomass, and solar energy. The demands for energy is increasing by years with some challenges such as the decreasing source of fossil fuels, food versus fuel crisis, and greenhouse gas (GHG) emission that needs to be taken into consideration [11]. In Malaysia, the development of renewable energy is still rather slow. Although, in 10th Malaysia plan, renewable energy usage has to increase >1% in 2009 to 5.5% of total electricity generation in 2010, although several fiscal incentives have been launched by the Malaysian government [89]. On the other hand, Malaysia is geographically located in the tropical and humid climate region which provides easy access to variety of biomass resources. Biomass resources are mainly from palm oil, wood, and agro-industries [90]. Malaysia devotes 11% of the total land area with 62% of the economy agricultural land for planting palm oil. If 20% of palm oil productions are turned into biofuels, it can replace 64% of diesel consumption, and at the same time cutting off 41% of imported crude oil [91]. From these facts, we can estimate the amount of biomass and biofiber waste produced yearly. Thus, there is a potential need to convert the residue into a valuable product by converting them into biomass energy feedstock. Economically, biomass waste from palm oil plantation such as empty fruit bunch (EFB) can be used as resources for conversion of bioethanol, since the production is 6.1 million tons dry EFB and is forecasted to increase to 7.6 million tons in 2025 as shown in **Table 5** [92].


**Table 5.** Potential ethanol and forecasted EFB production by MPOB based on 22% EFB to FFB and moisture at 65% (93).

Currently, biorefineries are increasingly focused on integrated process design for maximum valorization of fractionated biomass components for fuels and a spectrum of co-products. This multi-product "integrated biorefineries concept" is a platform for development of modern biorefineries with economic competitiveness to the current petroleum industry [10]. According to the IEA (International Energy Agency) report from the assessment of available residue in 2030, it was predicted that 10% of global residues could yield around 155 billion lge (5.2 EJ) lignocellulosic ethanol or almost around 4.1% of the projected transport fuel demand in 2030, and 25% of global residues converted to either ethanol, diesel, or syngas that could contribute to 385–554 billion lge (13–23.3 EJ) globally [94].

In conclusion, the viability of biomass and biofiber materials should concentrate more on developing a complete understanding of these materials to form a foundation for significant advancement in sustainable energy. Development in characterization and overcoming the difficulty for enzymatic saccharification of different raw materials is crucial for the develop‐ ment of economically competitive processes based on enzymatic treatment.
