Design and Planning of Biofuels Produced from Algae

Abstract

This thesis investigates the profitability of converting microalgae into biofuel using hydrothermal
liquefaction the goal is to produce 100 000 tons of bio-oil each year. It explores various microalgae
species and cultivation methods, identifying Chlorella vulgaris with a rotating attached biofilter as the
optimal choice due to its high biomass concentration, eliminating the need for dewatering and expensive
harvesting processes. The study includes a detailed simulation in Aspen Plus with an integrated process
with HTL operating at 200 bar and 320 degrees celsius and hydrogen treatment operating at 15 bars and
350 degrees celsius. The simulation also incorporates components such as heat exchangers and separation
units. The study also goes in briefly about the components needed to make the process work such as a
hydrogen plant, wastewater treatment and a burner for gas. Cost analysis is conducted in Excel and
evaluates both operational and capital expenses.
The Aspen simulations indicate a bio-oil yield of 60%. Post-hydroprocessing and hydrocracking, the
bio-oil composition includes 77% diesel, 15% naphtha, and 8% gas. The analysis estimates a capital
payback period of 49 years under standard conditions. A theoretical optimal scenario was made adjusting
key parameters to their theoretical maxima, reducing the payback period to 5 years. The conclusion for
the process is that the algae cultivation is expensive to build to make it profitable.

Popular Abstract

Fossil fuels like coal, oil, and natural gas have been the backbone of our energy systems for centuries. They powered the Industrial Revolution, revolutionized transportation, and fueled our homes and industries. However, these finite resources, derived from ancient organic matter, are depleting and pose serious environmental issues, such as contributing to global warming through greenhouse gas emissions. As developing nations improve living standards, their energy demands increase, which further exacerbates the delicate balance between progress and environmental sustainability.

Biofuels offer a promising alternative. They are renewable energy sources derived from processing biomass. The first generation of biofuels comes from oil-bearing seeds and edible crops but competes with food resources. The second generation uses non-food biomass, often by-products of the food industry, presenting a better option. The third generation harnesses algae, which is particularly promising due to its rapid biomass production and high oil content.

This study investigates various microalgae species for biofuel production, comparing their growth and cost-effectiveness. It explores different cultivation methods to maximize yield and minimize expenses. The research then focuses on hydrothermal liquefaction (HTL), a process that converts algal biomass into biocrude oil. This process is simulated using Aspen Plus software to construct and optimize the chosen design. The simulation also examines the hydrogen treatment of biocrude to enhance its usability.

In summary, while fossil fuels have driven our progress, their drawbacks necessitate alternatives. Biofuels, especially those from algae, offer a sustainable solution, though further research and technological advancements are essential to make them economically viable.

• author: Persson Yng, Axel
• supervisor: Christian Hulteberg
• organization: Chemical Engineering (M.Sc.Eng.)
• course: KETM05 20241
• year: 2024
• type: H2 - Master's Degree (Two Years)
• subject: Technology and Engineering
• keywords: algae, hydrothermal liquefication, HTL, biofuel, hydrotreatment, chemical engineering
• language: English
• id: 9178387
• date added to LUP: 2024-12-11 08:35:57
• date last changed: 2024-12-11 08:35:57