Biomass to levulinic acid: A techno-economic analysis and sustainability of biorefinery processes in Southeast Asia.

Aligned with Singapore's commitment to sustainable development and investment in renewable resources, cleaner energy and technology (Sustainable Singapore Blueprint), we report a techno-economic analysis of the biorefinery process in Southeast Asia. The considerations in this study provide an overview of the current and future challenges in the biomass-to-chemical processes with life-cycle thinking, linking the land used for agriculture and biomass to the levulinic acid production. 7-8 kg of lignocellulosic feedstock (glucan content 30-35 wt%) from agriculture residues empty fruit bunches (EFB) or rice straw (RS) can be processed to yield 1 kg of levulinic acid. Comparisons of both traditional and "green" alternative solvents and separation techniques for the chemical process were modelled and their relative energy profiles evaluated. Using 2-methyltetrahydrofuran (2-MeTHF) as the process solvent showed to approx. 20 fold less energy demand compared to methyl isobutyl ketone (MIBK) or approx. 180 fold less energy demand compared to direct distillation from aqueous stream. Greenhouse gases emissions of the major operations throughout the supply chain (energy and solvent use, transport, field emissions) were estimated and compared against the impact of deforestation to make space for agriculture purposes. A biorefinery process for the production of 20 ktonne/year of levulinic acid from two different types of lignocellulosic feedstock was hypothesized for different scenarios. In one scenario the chemical plant producing levulinic acid was located in Singapore whereas in other scenarios, its location was placed in a neighboring country, closer to the biomass source. Results from this study show the importance of feedstock choices, as well as the associated plant locations, in the quest for sustainability objectives.

Bioenergy co-products derived from microalgae biomass via thermochemical conversion--life cycle energy balances and CO2 emissions.

An investigation of the potential to efficiently convert lipid-depleted residual microalgae biomass using thermochemical (gasification at 850 °C, pyrolysis at 550 °C, and torrefaction at 300 °C) processes to produce bioenergy derivatives was made. Energy indicators are established to account for the amount of energy inputs that have to be supplied to the system in order to gain 1 MJ of bio-energy output. The paper seeks to address the difference between net energy input-output balances based on a life cycle approach, from "cradle-to-bioenergy co-products", vs. thermochemical processes alone. The experimental results showed the lowest results of Net Energy Balances (NEB) to be 0.57 MJ/MJ bio-oil via pyrolysis, and highest, 6.48 MJ/MJ for gas derived via torrefaction. With the complete life cycle process chain factored in, the energy balances of NEBLCA increased to 1.67 MJ/MJ (bio-oil) and 7.01 MJ/MJ (gas). Energy efficiencies and the life cycle CO2 emissions were also calculated.

Life cycle energy and CO2 analysis of microalgae-to-biodiesel: preliminary results and comparisons.

Despite claims that microalgal biofuels are environmentally friendlier alternatives to conventional fuels, debate surrounding its ecological benefits or drawbacks still exists. LCA is used to analyze various biofuel production technologies from 'cradle to gate'. Energy and CO(2) balances are carried out for a hypothetical integrated PBR-raceway microalgae-to-biodiesel production in Singapore. Based on a functional unit of 1 MJ biofuel, the total energy demands are 4.44 MJ with 13% from biomass production, 85% from lipid extraction, and 2% from biodiesel production. Sensitivity analysis was carried out for adjustments in energy requirements, percentage lipid contents, and lower/higher heating product value. An 'Optimistic Case' was projected with estimates of: 45% lipid content; reduced energy needs for lipid extraction (1.3 MJ per MJ biodiesel); and heating value of biodiesel (42 MJ/kg). The life cycle energy requirements dropped significantly by about 60%. The results are compared with other published case studies from other countries.

Surface modification of PCL-TCP scaffolds improve interfacial mechanical interlock and enhance early bone formation: an in vitro and in vivo characterization.

Pretreatment of polycaprolactone-20% tricalcium phosphate (PCL-TCP) scaffolds under alkaline conditions can be utilized to alter surface characteristics for enhanced early bone formation. PCL-TCP scaffolds were treated with sodium hydroxide (NaOH) at various time intervals (group A: untreated, group B: 3M NaOH for 48 h, and group C: 3M NaOH for 96 h). In vitro results showed a greater degree of physical changes in the NaOH-treated scaffolds (B and C) than the untreated group (A). Clearly, the NaOH-treated scaffolds showed an increased surface roughness than the untreated ones. A significantly large number of "channel-like" pits and greater average pit sizes were detected in groups B (14.51 +/- 10.9 microm) and C (20.27 +/- 14.3 microm); and absent in group A. In addition, treated scaffolds had a significant reduction of the water contact angle (40.9-58.2%). Favorably, the pore dimensions and scaffold rod thickness remained unchanged throughout the experiment. When implanted in the calvaria of rabbits, NaOH-treated scaffolds reported greater early matrix deposition and bone formation from scanning electron images and Micro-computed tomography analyses. In conclusion, pretreatment of PCL-TCP scaffolds with NaOH increases the wettability and surface area for initial matrix deposition and early bone ingrowth.