**1. Introduction and Problem Statement**

The International Energy Agency (IEA) reported [1] that biofuel production for the transportation sector needs to triple by 2030 to 280 Mtoe to be on track with the Sustainable Development Scenario (SDS). This is equivalent to 10% of the global transport fuel demand, as compared to 3% global demand [1]. Table 1 shows the forecast annual production growth vs required production growth to meet SDS demand in 2030. Among the six countries/regions presented, China and ASEAN are among those with production growth that will possibly meet required biofuel production by 2030 under SDS. In 2017, the Chinese government announced to roll out the mandatory blending of 10% ethanol in gasoline nationwide by 2020 [2]. Significant development of new ethanol production capacity is currently underway in order to meet the target, which is equivalent to 15 Mt of biofuel annually, or around 45 Mt of corn. In ASEAN, biofuel policy is robust as domestic biofuel consumption is a means for energy security while promoting socio-economic development through ensuring demand for strategically critical agricultural commodities (Table 2). Among the 10 ASEAN member states, Indonesia, Malaysia, Philippines, Thailand and Vietnam are those with existing comprehensive policies on biofuel.


**Table 1.** Forecast growth vs required growth to meet the year 2030 target under SDS [1].


**Table 2.** ASEAN countries with comprehensive biofuel policy.

It is noted that Indonesia is the only ASEAN country with a target for a bioavtur (biojet fuel) mix of 5% by 2025 and 10% by 2050. The feedstocks used for biofuel production in ASEAN countries are palm oil (Indonesia, Malaysia, Thailand), coconut oil (the Philippines), sugarcane (Thailand, the Philippines) and cassava (Thailand, Indonesia). With Indonesia and Malaysia being the world top two producers of palm oil, Thailand being the world's second producer of sugarcane after Brazil, Indonesia and Thailand being the world's top second and third cassava producers, Indonesia and the Philippines being the top world producers of coconut oil, it is not an exaggeration to call Southeast Asia a rice bowl with

huge regional potential for bioenergy production. Since biofuel carries a sustainable label as vehicle fuel when compared to conventional fossil fuels like gasoline or diesel, sustainability governance and a biofuel supply chain framework are essential to ensure that large scale biofuel consumption achieve its environmental benefits while delivering tangible economic and social benefits. Besides land-based vehicles, scaling up of biofuel consumption is also expected in the maritime and aviation sectors in the form of drop-in fuels, before more advanced alternative fuels like a solar jet, or hydrogen, become commercially viable. A decision-making level supply chain management is essential when formulating policies that sustainably promote biofuel production while providing investor confidence through financial de-risking measures or market instruments. De Meyer et al. [12] reviewed existing optimisation methods or models for optimisation in the field of biomass supply chain design and management. Most of the models reviewed had a case study in the EU, US and Brazil, with some case studies in China appearing in recent publications. Atashbar et al. [13] carried out a similar review on the modelling and optimisation of biomass supply chains. Most review articles are surrounding either solely on the methods of biomass supply chain management models, or solely on the potential, targets and current status of bioenergy in certain countries.

There has been a gap between how these supply chain management models could be used to plan for more sustainable biofuel production, considering the robust policy context of each biofuel producing countries. This is especially important for policymakers when it comes to decision making based on evidence. For ASEAN countries that possess significant feedstock resources, this is especially important so that food security and environmental sustainability are not compromised. This paper aims to first review the existing operational methods used to optimise the bioenergy supply chain, from upstream decision-making operational management optimisation model to downstream bioenergy trade model; then followed by a review on biofuel policy in ASEAN countries and challenges faced when implementing the policy. Only biofuel targets, policies and status of Indonesia, Malaysia and Thailand have been reviewed as there is existing comprehensive biofuel policy with similar bioenergy crops. The discussion will be made based on how the existing operational methods used in managing biomass supply chain at decision-making level could be used to tackle the challenges faced, or what are the research gap/blind spot/assumption made in existing methods that overlooks the consideration at the decision-making level. Most ASEAN countries that have biofuel mixes in the early days are motivated by energy security to reduce fuel imports and socio-economic factors as it creates jobs for their local communities. With increasing motivation towards carbon mitigation potential of biofuel in achieving sustainability target, it will be interesting to look into this matter and how each factor interact with each other when it comes to bioenergy planning.
