(105e) Techno-Economic Analysis of an Integrated Approach to Produce Bio-Methanol from Micro-Algae in the UAE

Global economic growth and energy demand go hand in hand. With future energy demands predicted to rise between 17% to 50% by 2040, heavy reliance on fossil fuels to meet these demands can pose drastic consequences, where the global atmospheric temperature is likely to rise above 3.6 °C, causing detrimental impacts on ecological communities and alarming rise in greenhouse gas emissions. This necessitates development of renewable and sustainable energy technologies. To control and limit the effects of climate change the Paris Agreement, established during the 21^st Conference of Parties (COP21), and the United Nations Framework Convention on Climate Change (UNFCCC) encourage the application of bio- based energy sources.

Micro-algae is one of the most promising non-food crop feedstocks. Due to its ability to be processed into both bioenergy and valuable co-products, and to fix CO₂ using sunlight at ten times terrestrial plant efficiency, micro-algal cultivation is one of the most promising processes of carbon capture today. The United Arab Emirates has a sizable potential for algal biofuel production owing to its vast deserts, long shorelines, year-round sunny days, flue gas, seawater and wastewater availability, and the wealth of native adapted algal species with salinity tolerance twice as high as that in the gulf waters. As UAE is hosting the upcoming UN Conference of Parties (COP28), more research is required to investigate the potential of micro-algae production and conversion.

In this proposed research, an integrated approach is taken to produce bioenergy from micro- algae, by modelling bio-methanol production through gasification of biomass using Aspen Plus. The key stages of the process are gasification, syngas post treatment, methanol synthesis followed by purification. The developed model performance is then evaluated for three different types of micro-algal species: (1) S. Acuminatus (2) N. Oculata and (3) S. Almeriensi. The performance of the micro-algal species was also compared with a plant biomass (pine). The simulation results were found to be comparable to experimental data available in literature.

Amongst the three feedstocks, S. Acuminatus was found to produce the greatest amount of bio-methanol and the greatest HHV value under identical conditions. A sensitivity analysis was conducted to evaluate the optimum gasification temperature for obtaining maximum bio-methanol yield, for each of the feedstocks. The optimum temperature was found to be 860; 880; 860 and 840 °C for S. Almeriensi, N. Oculata, S. Acuminatus, and Pine Biomass respectively.

This model was then used to evaluate the economic feasibility of the proposed plant. The profitability indicators used in this case were IRR (%), ROI (%), NPV and Payback time. Since obtaining specific raw material costs for each micro-algal species was difficult, a general feedstock of Chlorella vulgaris is considered. A sensitivity analysis was conducted for wide range of bio-methanol selling prices and two Chlorella vulgaris feedstock prices ($269 and $45 per ton). The average bio-methanol selling price is $770 per ton. However, when applied as a shipping fuel, the cost of bio-methanol increases manifold to $3,336 per ton. Hence, the best scenario is when methanol is sold at the bunker prices. An IRR of 525% was recorded even when the raw material price was as high as $269 per ton.

The worst case was identified to be when the bio-methanol price was $693 per ton. Minimum profitability was obtained with a payback time of 14 years (without 3-year construction) with a plant lifespan of 20 years. An IRR of only 2.6 % was obtained.

Considering the standard average price of $770 per ton, an ROI of 2.6% and 13.2% was noted when raw material prices were $269 and $45 per ton, respectively. Therefore, the plant can be classified as feasible.

Given the current price of conventional methanol however, the bio-methanol is not yet commercially competitive. But, with emergence of the new legislature and regulations, the current focus on decarbonization and looking for more sustainable fuel alternatives, this should gradually reverse the trend. The sudden boom in the bio-methanol price for use as a shipping fuel for example is a sign pointing in this direction. Keeping sustainability at its core, biofuels are directly in line with the sustainable development goals of the United Nations and the commitments of COP27.