Synthesis of FAMEs can be catalyzed by either base or acid. The base — catalyzed reaction is faster but can also generate soaps [4]. The sulfuric acid-catalyzed reaction, while slower, is also better at esterifying free fatty acids by dehydration [27]. Heat can speed up the acid-catalyzed reaction but there is a tradeoff between speed and the cost of heating. The previous results showed that 5% sulfuric acid in methanol could both elute algae from the resin and convert lipids to FAME. To test how well a base-cat­alyzed transesterification reagent would work, algae bound to Amberlite was eluted with either potassium hydroxide/methanol or sodium methox — ide/methanol. We found that FAME yields from the sodium hydroxide/ methanol reaction were undetectable and yields from the sodium methox — ide/methanol reagent were 4% lower than using the sulfuric acid/metha — nol reagent. The reduced levels of FAME may be due to residual water, as shown by Griffiths [20], or to binding and depletion of the hydroxide or methoxide ions from solution by the anion exchange resin. For acid- catalyzed transesterification, we found that ethanol could be substituted for methanol with essentially identical results. Because of its low cost and wide availability, methanol is often used for biodiesel synthesis [4]. How­ever, ethanol cost may decrease in the future as advances in bioethanol productions lead to increases in supply.

An alternative or addition to the production of biodiesel is the production of bio-ethanol from the carbohydrates and starches in the algal cells. De­pending upon the strain and composition of the algal species significant yields of ethanol can be produced from algal biomass [78-81]. Strains with filamentous cells such as Spirulina and Spirogyra are considered most promising due to the higher percentage of carbohydrate in their make­up. The conventional process of producing bioethanol using hydrolysis and fermentation is well understood for many feedstocks but optimal con­version has not yet been achieved for algal biomass. Similarly to lipid extraction, the first stage in the process is the disruption of the biomass cells which can be carried out using numerous techniques including bead­beating, autoclaving, microwaving and acid or alkali treatment. Once the cells have been disrupted the carbohydrates and starches can be converted into sugars using enzymatic or acid hydrolysis. Following hydrolysis the sugars are then be fermented with yeast (typically S. cerevisiae or S. baya — nus) which will provide a broth of up to 17% (v/v) ethanol depending upon the concentration of sugars (AB Mauri, personal correspondence). The next step to produce bioethanol is to distil the broth to produce an ethanol concentration of around 98% (v/v) then further refinement of the ethanol produces a fuel which can be used as an additive to conventional engines or up to a maximum of 85% in specialised E85 engines [82].

As the concept of converting algal biomass into bioethanol is relatively under-researched most studies have simply focussed upon investigating what ethanol recoveries are possible. In an early study by Hirano et al. [79] a variety of freshwater and marine algae was selected for testing. Chlo — rella vulgaris was found to contain a high proportion of starch (37%) and a recovery of 65% of ethanol from the starch was obtained using enzymatic hydrolysis followed by fermentation with S. cerevisiae. An overall recov­ery of 24% from the biomass was therefore obtained. Using the strain Chlorococum spp, a conversion efficiency of about 38% of the ethanol was obtained [78], which can be considered promising however this was an optimal value and no consideration was given to the energy requirement of processing. What is interesting from this research is that when the lipid content of the biomass was recovered prior to fermentation, ethanol yields were far higher [78]. This suggests that biomass could provide both diesel and ethanol, maximising potential recoveries. Nguyen et al. [83] found in several studies that yields of up to 29% ethanol recovery efficiency were possible using Chlamydomonas reinhardtii. The studies mentioned above prove that high ethanol yields from algal biomass are possible but further studies are necessary to assess the viability in terms of energy balance, economics and environmental impacts.

Alternative methods of ethanol production have been investigated which focus upon intracellular ethanol production in which algae produce ethanol under dark, anaerobic conditions. The species which are capable of the process are cyano-bacteria and include the species: Chlamydomo­nas reinhardtii, Oscillatoria limosa, Microcystis, Cyanothece, Cicrocys — tis aeruginosa and Oscillatoria spp. [84]. The process requires the algae to be cultivated in a closed environment with the addition of CO2 under which conditions, it is believed that concentrations of between 0.5 and 5% ethanol can be produced. Hirano et al. [79] investigated this phenomenon using Chlamydomonas reinhardtii and Sak-1 isolated from salt water, and a maximum yield of 1% , w/w produced by C. reinhardtii was reported. The ethanol-water mix can then be extracted and treated further to produce highly concentrated ethanol for fuel use. The benefits of the process are that no other organisms (e. g., enzymes and yeast) are required for hydro — lysis/fermentation and the algae remains unaffected and can continue to grow without a requirement for harvesting. The energy requirements are likely to be lower than those necessary for conventional fermentation of biomass however the two methods need to be directly compared. In their study Luo et al. [84] show that the whole process provides a positive en­ergy balance with the greatest surplus of energy when the maximum etha­nol concentration is produced. Additionally the greenhouse gas emissions compare well to emissions via gasoline production but to reach 20% of the emissions from gasoline (a government aim) would require further reduc­tions in the process chain.

Bioethanol production from algal biomass is still very much in its infancy, the concept is proven but the viability is not. Further life-cycle analyses are required to understand the potential of the concept. Post lipid processing and intracellular ethanol production look promising as energy consumption is minimised, further research will establish viability.

IS IT A VIABLE ALTERNATIVE?

FIROZ ALAM, ABHIJIT DATE, ROESFIANSJAH RASJIDIN, SALEH MOBIN, HAZIM MORIA, and ABDUL BAQUI

4.1 INTRODUCTION

The global climate change, rising crude oil price, rapid depletion of fossil fuel reserves, and concern about energy security, land and water degrada­tion have forced governments, policymakers, scientists and researchers to find alternative energy sources including wind, solar and biofuels. The bio­fuel production from renewable sources can reduce fossil fuel dependency and assist to maintain the healthy environment and economic sustainabil­ity. The biomass of currently produced biofuel is human food stock which is believed to cause the shortage of food and worldwide dissatisfaction especially in the developing nations. Therefore, microalgae can provide an alternative biofuel feedstock thanks to their rapid growth rate, greenhouse gas fixation ability (net zero emission balance) and high production capac­ity of lipids as microalgae do not compete with human and animal food crops. Moreover, they can be grown on non-arable land and saline water. Biofuels are generally referred to solid, liquid or gaseous fuels derived from organic matter [1]. The classification of biofuels is shown in Fig. 1. These classifications are: a) Natural biofuels, b) Primary biofuels, and c) Secondary biofuels. Natural biofuels are generally derived from organic sources and include vegetable, animal waste and landfill gas. On the other hand, primary biofuels are fuel-woods used mainly for cooking, heating, brick kiln or electricity production. The secondary biofuels are bioethanol and biodiesel produced by processing biomass and are used in transport

о CO

Produced from — Firewood, plants — Wood chips — Forest — Animal waste — Landfill gas — Crop residues

Biodiesel produced from — Microalgae — Mircobes

Bioethanol produced from — Wheat, barley, corn — Potato, sugarcane, beet — Oil seeds (soybeans coconut, sunflower rape seed — Animal fat, used cooking oil /

Bioethanol & Biodiesel produced from — Cassava, jatropha miscanthus — Straw, grass, wood

FIGURE 1: Biofuel production sources (biomasses) (adapted from [2])

sectors [1]. The secondary biofuels are sub classified into three so called generations, namely, a) First generation biofuels, b) Second generation biofuels, and c) Third generation biofuels based on their different features such types of processing technology, feedstock and or their development levels [2].

Despite having potential in producing carbon neutral biofuels, the first generation biofuels possess notable economic, environmental and political concerns. The most alarming issue associated with first generation biofu­els is that with the increase of production capacity, more arable agricultur­al lands are needed for the production of first generation biofuel feedstock resulting in reduced lands for human and animal food production.

The increased pressure on arable land currently used for food produc­tion leads to severe food shortages, especially in developing countries of Africa, Asia and South America where over 800 million people have been suffering from hunger and malnutrition from severe shortages of food. With the growing world’s population, the demand for food is increasing — while the arable land is decreasing. The intensive use of fertilizer, pesti­cides and fresh water on limited farming lands can reduce not only the food production capacity of lands but also cause significant environmental damage [15]. Therefore, enthusiasms about first generation biofuels have been demised. Increasing use of first generation biofuels will inevitably lead to increasing the price of food beyond the reach of the under privi­leged. The political consequences of this could be difficult to contain.

As first generation biofuels are not viable and receive lukewarm re­ception, researchers focused on second generation biofuels. The primary intention here is to produce biofuels using lignocellulosic biomass, the woody part of plants which do not compete with human food chain di­rectly [2]. As shown in Fig.1, main sources for second generation biofuels are predominantly agricultural residues, waste (e. g., trimmed branches, leaves, straws, wood chips, etc.) forest harvesting residues, wood process­ing residues (e. g. saw dust) and non-edible components of corn, sugar­cane, beet, etc. However, converting the woody biomass into fermentable sugars requires sophisticated and expensive technologies for the pretreat­ment with special enzymes making second generation biofuels economi­cally not profitable for commercial production [2, 4].

Hence, the focus of research is drawn to third generation biofuels. The main component of third generation biofuels is microalgae as shown in

Fig. 1. It is currently considered to be a feasible alternative renewable en­ergy resource for biofuel production overcoming the disadvantages of first and second generation biofuels [1- 2, 5, 16]. The potential for biodiesel production from microalgae is 15 to 300 times more than traditional crops on an area basis [2]. Furthermore compared with conventional crop plants which are usually harvested once or twice a year, microalgae possess a very short harvesting cycle (1 to 10 days depending on the process), allow­ing multiple or continuous harvesting with significantly increased yields [2, 15]. Additionally, the microalgae generally have higher productivity than land based plants as some species have doubling times of a few hours and accumulate very large amounts of triacylglycerides (TAGs). Most im­portantly, the high quality agricultural land is not required for microalgae biomass production [3].

Aspects of EMF topology in the time domain have been studied by re­searchers looking at the influence on biological systems from combined AC and DC EMFs in superposition [58-61]. It has been shown that the cellular response to the orientation of the fields is distinct depending whether the AC and DC fields are perpendicular and parallel to each other. It was found that the perpendicular orientation is dominant in an intensity — dependent non-linear manner [61]. There is a fundamental difference in the spatial pattern of cellular response between DC and pulsed stimulation [62]. Several studies report that the relative orientation of AC and DC magnetic fields appears to be critical for a number of calcium-dependent cell processes. The data suggests that DC magnetic fields influence bio­logical membranes in a somewhat different manner than low frequency AC magnetic fields [1].

Functionalized weak anion exchange resins used in this study were syn­thesized in the manner stated above, using 6 g of EGDMA, 3 g of IM, and 1 g of DEG (EGDMA:IM:DEG), or 6 g of DVB and 4 g of DMA (DVB:DMA), with a solution of 5 mL of toluene (porogen) and 5 mL 3% acetic acid (dispersing agent). Steady-state binding capacity was deter­mined by agitating 2 g of resin in a 500 mL flask containing 100 mL of KAS603 at 0.4 g/L concentration for 15 min. The suspension containing unbound algae was filtered off and resin transferred into columns. FAME was directly transesterified from the resin as stated previously using 100 mL of 5% sulfuric acid-methanol. For comparison, algae was bound and eluted from a parallel set of Amberlite resin. Because of the higher binding capacity of resin, columns were eluted for 3 consecutive cycles using the same transesterification reagent to ensure complete removal. After reac­tion for 12 h as room temperature, FAME was recovered by extracting twice with 20 mL of hexane. The recovered organic phase was dried by ro­tary evaporation, and the residue resuspended in 1 mL hexane:isopropanol (3:1, v/v) for HPLC analysis.

Usually microalgae only synthesize small amounts of triacylglycerols (TAGs) under normal nutrient conditions, but can synthesize a large num­ber of TAGs with a significant change in the fatty acid composition un­der stress conditions. Limiting nutrient availability such as nitrogen and phosphorus starvation during microalgae cultivation is a common meth­od to induce lipid synthesis [30,31]. When the nitrogen is exhausted and becomes the limiting factor, microalgae will continue to absorb organic carbons, which are to be converted to lipids. The nutrient limitation also results in a gradual change in lipid composition, i. e., from free fatty acids to TAGs which are more suitable for biodiesel production [32]. Phospho­rus is another important nutrient that influences algae growth and lipid accumulation. Khozin-Goldberg et al. [33] found that phosphate limitation could cause significant changes in the fatty acid and lipid composition of Monodus subterraneus. Some studies found that phosphorus deficiency led to reduced lipid content of Nannochloris atomus and Tetraselmis sp.

[34] . Silicon is a necessary element for the growth of diatom. Roessler

[35] found that silicon deficiency could induce lipid accumulation in Cy — clotella cryptica by two distinct processes: (1) An increase in the propor­tion of newly assimilated carbons which are converted to lipids; (2) A slow conversion of previously assimilated carbon from non-lipid compounds to lipids. Unfortunately, higher lipid content achieved through nutrient limitation is usually at the expense of lower biomass productivity because nutrient deficiency limits cell growth. As mentioned above, lipid produc­tivity, representing the combination of lipid content and biomass yield, is a more meaningful performance index to indicate the ability of lipid production of microalgae. Therefore, it is necessary to develop a nutrient management strategy which will first facilitate rapid biomass accumula­tion and then induce lipid accumulation in order to achieve maximum lipid productivity.

As discussed, the only potentially sustainable cultivation method currently available is the use of open ponds. This is because of their lower energy requirements compared to PBRs. Open ponds require a far greater area of land for the mass of biomass produced and area requirements need to be considered for individual cases. The necessary area will be dependent upon the volume of wastewater that requires treatment, pond depth, nutri­ent loading, discharge limits and hydraulic retention times (HRT).

If the focus of algal cultivation is for wastewater treatment the treat­ment efficiency will have a great impact upon the pond area required. Treatment of water with algae depends upon the productivity of the algae, the higher the productivity the greater the nutrients assimilated. Hydrau­lic retention times of around 10 days are most common [55, 96] and as the HRT increases, the area required increases proportionally. It may be important to minimise the area requirements by reducing cultivation time but nevertheless if the wastewater discharged from the system is above the required limits then the time is likely to be too short. The HRT of each sys­tem will depend upon the influent nutrient loading and limits of discharge and therefore must be calculated accordingly.

The water consumption and water withdrawal required for transportation via bio-oil and biomass fuel (methane) produced in this production path­way are calculated based on the methodology presented by King and Web­ber [33]. Consumption and withdrawal are defined as:

“Water consumption describes water that is taken from surface wa­ter or a groundwater source and not directly returned. For example, a closed-loop cooling system for thermoelectric steam power genera­tion where the withdrawn water is run through a cooling tower and evaporated instead of being returned to the source is consumption. Water withdrawal pertains to water that is taken from a surface water or groundwater source, used in a process, and (may be) given back from whence it came to be available again for the same or other pur­poses. To determine the water consumption or withdrawal for each input, the amount of each energy or material input is multiplied by the water equivalent for that input.” [33].

and the water withdrawal intensity, WWI, is defined as:

WW

WWI =

кво ‘ EEB0 + Vbmf + FEbmf)

where WC is the water consumed per liter of growth volume processed, WW is the water withdrawn per liter of growth volume processed, VBO and VBMF are the volumes of bio-oil and biomass fuel (methane) produced per liter of growth volume processed, FEBO and and FEBMF are the fuel economy values for transportation via bio-oil (28 miles/gallon, 11.8 km/L)
and methane fuels (0.2 miles/standard cubic foot, 0.01 km/L). Thus, these metrics are calculated as the water required (consumed or withdrawn) for operating the production pathway shown in Figure 1 divided by the total distance that could be traveled using the bio-oil and the biomass fuel pro­duced (assuming typical conversion efficiencies). The water consumption and water withdrawal include direct water inputs (e. g., water supplied to the growth volumes) and indirect water inputs (e. g., water used during nitrogen fertilizer production and electricity generation), thereby yield­ing a second-order water analysis. The energy return on water investment (EROWI) is a similar metric for evaluating water intensity [9,34] and can be calculated from the data in this study that are reported in Tables 3A and 4A. However, this metric does not consider the energy quality of the fuels produced, and therefore the WCI and WWI were used as the main metrics for evaluating water intensity in this study.

5.3 RESULTS

A long history of extensive research on intercellular communication is found in the literature, which has primarily focused on receptor-based chemical signaling, molecular mechanisms, cell recognition, and cell sur­face receptors; however very few studies have focused on light-mediated interactions of cells, tissues and whole organisms [115]. Kaznacheyev and colleagues in Russia performed over 12,000 experiments in studying distant intercellular communication from two physically separated living tissues or cultures. They used two hermetically sealed vessels attached to each other via an interchangeable window composed of glass or quartz, where each vessel contained an identical culture. One of the vessel’s cells was treated with a specific toxin, i. e., virus, chemical or radiation, while keeping the neighboring culture physically isolated from it. If a quartz window was used, so as to allow UV in addition to the visible and IR range of photons, approximately 75% of the physically isolated cultures began exhibiting toxin specific morphological stress and cell death 12 h after the directly exposed neighbor. However no effect was found if glass was used in the window to block the UV radiations indicating that biophoton signals passing through the quartz window were responsible for the specific mor­phological response [116-121]. By implementing a photomultiplier tube (PMT), they observed that normal functioning cells emit a uniform photon flux, while with the introduction of a toxin the radiation flux which inten­sifies at periodic intervals which depend on the different exposed toxin [120]. The harmonic relationship between the UV, visible and IR bands and their phase orientation has been suggested as a potential mechanism of intercellular communication [122] since the existence of coherent fields gives rise to destructive and constructive interference patterns in the space between living cells [123]. The biocommunication in these mutual inter­ference regions leads to an optimized signal/noise ratio as the wave pat­terns achieve maximum destructive interference or compensation. Once the coherent superposition of modes of biophoton fields breaks down, one expects an increase in biophotonic emission, which was confirmed by Schamhart and Wijk [124], by examining the delayed luminescence of tu­mor cells as they lose their coherence and capacity for destructive interfer­ence by exhibiting exponential as opposed to hyperbolic decay [123]. The importance of biophotons in inter — and intracellular communication has been further confirmed through many other experiments that have been listed in the Table 1.

DOUGLAS AITKEN and BLANCA ANTIZAR-LADISLAO

2.1 INTRODUCTION

In the current climate there are many reasons for considering alternative fuel sources and algae has been heralded as a potential “silver bullet”, however, after initial excitement it appears that the concept will not be commercially viable for at least 10 years. The technology to produce fuel from algae is currently available and vehicles have been powered by this feedstock in a number of cases [1]. As a commercially viable alternative to fossil fuels, however, the technologies are not yet there, the energy bal­ance of producing the fuel is high, the economics cannot compete and the overall sustainability is in doubt. The concept of algal fuels is one that has been with us since the 1950s [2]. Funding for this area of research has fluctuated roughly in line with rising and falling crude oil prices. One of the main contributors in pioneering algal fuels was Professor W. J. Oswald who designed systems to cultivate algae on a large scale in the 1950s and 60s [3, 4]. He developed the concept to remove nutrients from wastewater and provide a useful biomass for food or fuel. At the time however the viability of the concept appeared unachievable and as oil prices dropped so did funding for such projects. The price of oil however is continuing

to rise with little sign of slowing down and it is now important to focus once again on improving the viability of fuel from algal feedstock. This paper will investigate where we have come since the first research on algal cultivation and energy recovery was initiated, what is currently hindering the commercial application of the concept and where we need to go from here. Continued research will allow us to recover the maximum potential from algal biomass which will provide an increasingly important resource for us in the future as predicted by Professor Oswald [5].

The aim of this paper is to investigate the current state of algal bio-en­ergy production and consider what conventional and novel processes can be employed to provide a more sustainable approach. A focus is placed on the energetic consumption and the environmental acceptability and where combining value added benefits such as wastewater treatment and carbon mitigation through flue gas utilisation may be beneficial.

2.2 BACKGROUND