Global evaluation of biofuel potential from microalgae

Abstract

In the current literature, the life cycle, technoeconomic, and resource assessments of microalgae-based biofuel production systems have relied on growth models extrapolated from laboratory-scale data, leading to a large uncertainty in results. This type of simplistic growth modeling overestimates productivity potential and fails to incorporate biological effects, geographical location, or cultivation architecture. This study uses a large-scale, validated, outdoor photobioreactor microalgae growth model based on 21 reactor-and species-specific inputs to model the growth of Nannochloropsis. This model accurately accounts for biological effects such as nutrient uptake, respiration, and temperature and uses hourly historical meteorological data to determine the current global productivity potential. Global maps of the current near-term microalgae lipid and biomass productivity were generated based on the results of annual simulations at 4,388 global locations. Maximum annual average lipid yields between 24 and 27 m , corresponding to biomass yields of 13 to 15 g·m, are possible in Australia, Brazil, Colombia, Egypt, Ethiopia, India, Kenya, and Saudi Arabia. The microalgae lipid productivity results of this study were integrated with geography-specific fuel consumption and land availability data to perform a scalability assessment. Results highlight the promising potential of microalgae-based biofuels compared with traditional terrestrial feedstocks. When water, nutrients, and CO 2 are not limiting, many regions can potentially meet significant fractions of their transportation fuel requirements through microalgae production, without land resource restriction. Discussion focuses on sensitivity of monthly variability in lipid production compared with annual average yields, effects of temperature on productivity, and a comparison of results with previous published modeling assumptions. algae | global model | geographic information system | life cycle assessment | dynamic map R ecent volatility in oil prices, attributed to increased demand and limited resources, has led to the development of unconventional petroleum reserves, such as oil sands, and increased exploration of alternative and renewable fuel sources. Scalability limitations associated with traditional terrestrial biofuel feedstocks have renewed interest in next-generation feedstocks, such as microalgae. Microalgae offer many potential advantages over traditional terrestrial oil crops, including higher lipid productivities, a lack of competition for arable land, year-round cultivation, integration with saline and low-quality water sources, and a viable drop-in equivalent fuel product (1-5). These scalable advantages make microalgae a promising feedstock for biofuel production and a potential sustainable alternative to traditional petroleum fuels.The current near-term productivity potential for microalgae at large-scale currently is being estimated through the linear scaling of laboratory-based growth and lipid data, which has led to a large variance in report...

Algae for Africa: Microalgae as a source of food, feed and fuel in Kenya

“…High variability results in increased infrastructure which would create further operation costs. A study of the global biofuel potential from microalgae by Moody et al (2014) showed the western Kenyan city of Kisumu to maintain an average annual temperature close to the optimum and would therefore be able to maintain high biomass yields; making it an ideal location for microalgae cultivation (Moody et al, 2014).…”

“…A study carried out by Moody et al (2014) used largescale, validated, outdoor photobioreactor microalgae growth model based on 21 reactor-and species-specific inputs to model the growth of Nannochloropsis. The model accurately accounts for biological effects such as nutrient uptake, respiration, and temperature and uses hourly historical meteorological data to determine the current global productivity potential.…”

New challenges in microalgae biotechnology

“…Microalgae represent an alternative to land plants, since cultures could be developed in non-arable land, employing brackish, saline or even waste water, as well as carbon dioxide from flue gases as carbon source. Values for expected fuel productivity around 20,000 L per hectare and year seem reasonable for outdoor culture of microalgae (Moody et al 2014), although some substantially higher projections are frequently argued in the literature. However, most of the projected values originate from gross extrapolations, both in area and time, from short-term trials in small size facilities, if not directly from laboratory experiments.…”

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