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CURATOR
A pinboard by
A S M Mainul Hasan

A current PhD student in Molecular Plant Genetics who has a masters in Agrobiotechnology

PINBOARD SUMMARY

Highly innovative, yet simplistic solution to global energy crisis - let's get the ball rolling

Ever since the climate agreement has been reached unanimously in Paris in 2015, countries all over the world have agreed upon to cut emission of CO2 and other greenhouse gases. This summit was a timely wake up call for everybody in order to minimize global warming and keep world temperature rise below 2 degrees Celsius by the end of this century. Dependence on fossil fuels and over use of such materials over the past few centuries has put the earth on edge. As a result of that a shift in global focus towards alternative source of energy production is at its peak than ever before. The idea of making fuel from food crops such as wheat, corn, soybean, sugarcane etc. is around for quite sometime, and so is from algae.

Now, let us have a look at the basic aspects related to production of algal biofuel. The lipid or oily part of algae is extracted to generate biodiesel whereas the carbohydrate portion is exploited for manufacturing bioethanol. In addition to light and water, nitrogen and phosphorus are the two most crucial nutrients that is needed for algal growth. Upon initial anaerobic digestion by bacteria, waste-water could be used for algal growth as it is enriched with such nutrients. Marginal lands that are almost futile for farming are useful sites for cultivating algae. Some of the algal species such as Schizochytrium could produce oil amounting to nearly 77% of its dry weight compared to 2-3% of that in soybean.

However, the most striking feature of using algae is that it produces almost 300 times more oil per acre than the aforementioned crops. Besides, they have a life cycle of 1-10 days, which means much faster and less tedious outcome compared to the annual crops. In addition, algal growth eliminates the necessity of using herbicides and pesticides, thereby limiting pollution. Moreover, persistent use of food grains to produce biofuel would have huge impact on global food security which could be avoided by using algae for the same purpose.

In conclusion, significantly less afford for maintenance and high output makes algae as the top choice for production of biofuel and we would probably see more established companies as well as new entrepreneurs moving towards the direction of algal biofuel in future.

10 ITEMS PINNED

Theoretical Maximum Algal Oil Production

Abstract: Interest in algae as a feedstock for biofuel production has risen in recent years, due to projections that algae can produce lipids (oil) at a rate significantly higher than agriculture-based feedstocks. Current research and development of enclosed photobioreactors for commercial-scale algal oil production is directed towards pushing the upper limit of productivity beyond that of open ponds. So far, most of this development is in a prototype stage, so working production metrics for a commercial-scale algal biofuel system are still unknown, and projections are largely based on small-scale experimental data. Given this research climate, a methodical analysis of a maximum algal oil production rate from a theoretical perspective will be useful to the emerging industry for understanding the upper limits that will bound the production capabilities of new designs. This paper presents a theoretical approach to calculating an absolute upper limit to algal production based on physical laws and assumptions of perfect efficiencies. In addition, it presents a best case approach that represents an optimistic target for production based on realistic efficiencies and is calculated for six global sites. The theoretical maximum was found to be 354,000 L·ha−1·year−1 (38,000 gal·ac−1·year−1) of unrefined oil, while the best cases examined in this report range from 40,700–53,200 L·ha−1·year−1 (4,350–5,700 gal·ac−1·year−1) of unrefined oil.

Pub.: 08 Oct '09, Pinned: 23 Apr '17

Nutrient recovery and biogas generation from the anaerobic digestion of waste biomass from algal biofuel production

Abstract: Microalgae are gaining popularity as a source of biodiesel. Recycling fertilizer nutrients is critical to sustain large-scale biodiesel production because the global supply of surplus fertilizer is limited. This study demonstrates that anaerobic digestion of residual algal biomass from biodiesel production can provide additional nutrients and energy. Anaerobic digestion of Chlorella sorokiniana 1412 whole cell algae (WCA), sonicated algae (SA), and SA subjected to lipid extraction (LEA) in bench-scale batch reactors operated at 30 ± 2 °C for 42 days released a considerable amount of the nitrogen and phosphorus in the algal cells. Digestion of WCA, SA, LEA released 48.1, 77.4, and 61.5% of the total algal nitrogen as NH4+-N, and 87.7, 99.4, and 93.6% of the total algal P as soluble P, respectively. The energy recovery from algae biomass was quantified through the methane yield. The biochemical methane potential of WCA, SA and LEA was 0.298, 0.388 and 0.253 L methane per gram algal volatile solids, respectively. The conversion of LEA and WCA biomass to methane was very similar (38 and 41% on a COD basis, respectively), indicating that the energy yield was not significantly lowered by extraction of the lipid fraction (which accounted for 9% of algal dry weight). Sonication improved the access of hydrolytic enzymes to algal biopolymers (compensating in part for the energy lost due to lipid extraction). The results taken as a whole indicate that anaerobic digestion of LEA can provide considerable yields of methane and soluble nutrients.

Pub.: 28 Feb '17, Pinned: 25 Apr '17

Socioeconomic indicators for sustainable design and commercial development of algal biofuel systems

Abstract: Social and economic indicators can be used to support design of sustainable energy systems. Indicators representing categories of social well‐being, energy security, external trade, profitability, resource conservation, and social acceptability have not yet been measured in published sustainability assessments for commercial algal biofuel facilities. We review socioeconomic indicators that have been modeled at the commercial scale or measured at the pilot or laboratory scale, as well as factors that affect them, and discuss additional indicators that should be measured during commercialization to form a more complete picture of socioeconomic sustainability of algal biofuels. Indicators estimated in the scientific literature include the profitability indicators, return on investment (ROI) and net present value (NPV), and the resource conservation indicator, fossil energy return on investment (EROI). These modeled indicators have clear sustainability targets and have been used to design sustainable algal biofuel systems. Factors affecting ROI, NPV, and EROI include infrastructure, process choices, and financial assumptions. The food security indicator, percent change in food price volatility, is probably zero where agricultural lands are not used for production of algae‐based biofuels; however, food‐related coproducts from algae could enhance food security. The energy security indicators energy security premium and fuel price volatility and external trade indicators terms of trade and trade volume cannot be projected into the future with accuracy prior to commercialization. Together with environmental sustainability indicators, the use of a suite of socioeconomic sustainability indicators should contribute to progress toward sustainability of algal biofuels.

Pub.: 10 May '16, Pinned: 23 Apr '17

Life cycle energy demand from algal biofuel generated from nutrients present in the dairy waste

Abstract: In the USA, approximately 6 million tons of nitrogen and 1 million tons of phosphorus are being produced as a waste stream from the dairy operations. The main aim of this research was to estimate the potential of algal biofuel production, using waste nutrients present in the dairy waste, as well as performing a life cycle assessment to estimate the energy requirement of produced algal biofuel. Four different scenarios for algal biofuel production were simulated using different combinations of the following processes (i) algal-biodiesel-production, (ii) anaerobic-digestion (AD), (iii) pyrolysis and (iv) enzymatic-hydrolysis. Scenario 1 consists of AD and algal biodiesel production. Introduction of pyrolysis in the second scenario decreased biofuel production by ∼6% in the initial cycle and gradually increased to 25% in the later cycles. In the third scenario, biomass liquefaction through enzymatic hydrolysis was introduced to recover nutrients and sugars from the sludge generated from the AD process. Recovered nutrients and sugars were used for additional algal biodiesel production. Remaining sludge after the biomass liquefaction was applied on the agricultural land. As compared to the 1st scenario, further processing of the sludge through liquefaction increased the overall bioenergy production marginally. In the fourth scenario, biomass left after liquefaction was further processed through pyrolysis. In the fourth scenario, a 38% increase in the energy production was observed versus the 1st scenario. Additional energy production (compared to 1st scenario) through pyrolysis (Scenario 2) required additional 1.5 GJ of energy per GJ of energy produced and showed little variability. Additional energy production through the 3rd and the 4th scenario is not energetically favorable as compared to the 1st scenario. With respect to the 3rd scenario, energetically favorable additional energy can only be produced by the 4th scenario. Life-cycle energy-demand of the produced biofuel was varied from 0.35 to 0.68 GJ/GJ of energy produced. This study estimated that using dairy waste at a maximum of 3.14 billion GJ bioenergy could be produced.

Pub.: 20 Jul '16, Pinned: 23 Apr '17