The vast majority of all agricultural production is directed at feeding the world’s population; either directly, or indirectly by feeding livestock that supplies animal products. Other agricultural products, such as fibres for clothing, biomass for energy generation and tobacco production, make up a very small share of the total current agricultural production.

This means that developments in food demand and supply and the balance between them will heavily influence all agricultural and land use analyses, including the bioenergy potential analysis in this work. Forecast­ing these developments is a complex task for the following reasons:

• Demand: future food demand depends on the size of the world’s population and the composition of its diet. This diet, in turn, depends on parameters such as wealth and cultural choice. Particularly important is the intensity of animal products in that diet, as these require a large amount of animal feed.

• Supply: future food supply depends on the area available for food cultiva­tion and the food yield per unit of area. The evolution of this yield is hard to predict over larger timescales because it depends on numerous factors such as R&D results, technology adoption, education and sustainability require­ments.

• Balance of demand and supply: the balance between food supply and de­mand is poorly understood. It is often argued that the current food supply is adequate for the entire global demand, but that unequal distribution leads to food shortages in parts of the world.

The land available for bioenergy cropping in our work is strongly de­pendent on the assumptions made in the food analysis. Where possible, we have used conservative assumptions (i. e. assumptions close to business — as-usual scenarios), with one notable exception; a constraint on the con­sumption of meat, creating a more sustainable diet, see Section 3.1.3. We performed a sensitivity analysis by varying parameters on food demand and supply and the balance between them. The effects of these variations on land available for bioenergy cropping are presented in Table 6. They show that our results on sustainable bioenergy potential are indeed sensi­tive to developments in food demand and supply and the balance between them.

3.5 CONCLUSION

The Ecofys Energy Scenario requires a significant share of bioenergy supply to meet the remaining energy demand after using other renew­able energy options. We only include bioenergy supply that meets strict sustainability criteria and leads to high greenhouse gas emission savings when compared to fossil references. We safeguard this by applying a set of sustainability criteria to assess the sustainable bioenergy potentials from residues, wastes, complementary fellings, energy crops and algae.

We conclude that the potential identified in this study is capable of meeting the required demand of the Ecofys Energy Scenario [1] with bio­energy that meets these sustainability criteria and simultaneously accom­plishes high greenhouse gas emission savings. The amount of sustainable bioenergy used and the amount of land used for sustainable bioenergy cropping in the Ecofys Energy Scenario are both near the low end of the range of potential values found in literature. In our sensitivity analysis we find, as expected, that the potential area available for bioenergy cropping is sensitive to developments in food demand and supply and the balance between them.

6.3.4.1 SPATIAL SUPERPOSITION

The investigation of using multiple independent field sources has led to studies where the treatment area exhibits spatial topology from super­position. A magnetic therapeutic device that uses four nonuniform static magnets in four-pole symmetry demonstrates an increased rate of Myosin phosphorylation over control. The notion that the magnetic field ampli­tude is the only parameter involved to determine the outcome with mag­netobiology experiments has been shown to be false and it is suggested the topological parameters in a spatial domain, such as field gradient and symmetry might also be of relevance [57].

Mazur investigated the use of multiple magnetic fields in superposition on biological samples. He exposed S. cerevisiae to a six-pole electromag­net with coils of alternating polarity at a magnetic field of 0.39-0.52 T, while saturating it with pure molecular oxygen. The magnetic field has an influence on the biosynthesis of yeast and changes their enzymatic ac­tivity when grown under aerobic conditions as opposed to anaerobically cultivated yeast. He found that in the presence of a magnetic field, the oxygen saturation increased from 5.37 to 39.9 mg L-1 and simultaneously stabilized the pH. The initiation of fermentation occurred immediately af­ter mixing of the dough. It was found that there was an improvement in the physical qualitative property of rising strength, which was decreased from 76 minutes to 53 minutes in the presence of oxygen saturation and a magnetic field. It was also found that the increase in CO2 production was

3.7 times greater in the magnetic treated culture than the control, which in­dicates a significant increase in maltase activity. The amount of dissolved oxygen in water increased and was sharply activated in the presence of a magnetic field [58].

Hydrophobic resins used in this study were synthesized in bulk by com­bining 8 g of EGDMA and 2 g of HMA with 10 mL of toluene as the poro — gen. Resin synthesis was carried out in a round bottom flask fitted with an argon bubbler and heated to 60 oC with constant stirring. Polymerization was initiated by addition of 1 mol percent AIBN and continued until the mixture formed a brittle solid. The polymer was then dried at 55 oC for 12 h, scraped from the flask and ground by mortar and pestle. The crushed resin was then sized between #35 and #170 meshes to obtain beads of ap­proximately 100-500 pm diameter.

As an alternative to solvent extraction, FAME generated by sulfuric acid/methanol transesterification was collected by passing the reaction mixture over a hydrophobic resin bed. Here, the 100 mL of sulfuric acid/ methanol used to elute algae off the Amberlite resin was passed through a 10 mL polypropylene column containing 2 g of EDGMA-HMA resin. The resin was then eluted with 50 mL of hexane-ethyl acetate (3:1, v/v) solvent that was subsequently removed by rotary evaporation and the residue resuspended in 1 mL hexane-isopropanol (3:1, v/v) for HPLC analysis. For comparison, parallel samples of algae bound to Amberlite were eluted with 100 mL sulfuric acid/methanol and extracted with two 20 mL portions of hexane. After mixing and phase separation, the up­per organic phase was recovered, dried by rotary evaporation, and the residue resuspended in 1 mL hexane-isopropanol (3:1, v/v) for HPLC analysis.

The screening of strains from local habitats and elsewhere should be con­sidered as the first step in selecting high performance strains for biodiesel production. However, other approaches including genetic manipulation may be employed to optimize the lipid and biomass productivity of prom­ising strains obtained through the screening process. The modern biotech­nologies, such as genetic engineering, cell fusion, ribosome engineering, metabolic engineering, etc. are potential techniques to develop new algae strains with rapid growth and high lipid content [24,25]. Such techniques are the key to breakthroughs in microalgae biomass energy development. In the fatty acid biosynthesis pathway, acetyl-CoA carboxylase (ACCase) is the key rate-limiting enzyme that helps the substrates acetyl-CoA enter the carbon chain of fatty acids. Therefore, it is effective to enhance the expression of ACCase to promote the lipid synthesis in microalgae. Song et al. [26] successfully constructed a vector called pRL-489-ACC to real­ize the shuttle expression of the gene coding acetyl-CoA carboxylase in the fatty acid synthesis pathway. Zaslavskaia et al. [27] introduced a gene encoding a glucose transporter (glutl or hupl) into Phaeodactylum tricor-

nutumcan to allow the alga to grow on exogenous glucose in the absence of light. This represents progress of large-scale commercial production of microalgae with high lipid content by reducing limitations associated with light-dependent growth. In addition, phosphoenolpyruvate carboxylase (PEPC) is closely related to the fatty acid biosynthesis pathway because of the inhibition of PEPC activity redounding to catalyse acetyl-CoA to enter the fatty acid synthesis pathway. With successful clone of some PEPC gene in microalgae (such as Anabaena sp. PCC 7120 [28], Synechococcus vulcanus [29]) and detailed analysis of its sequence characteristics and structure, it will be possible to improve the lipid content of microalgae by regulation of PEPC expression by antisense technology [25].

Selecting an algal strain because of its beneficial properties is unlikely to be the most successful method of recovering energy from its cultivation. As recent studies have shown, producing high value biofuel from algae may not be the most effective means of energy recovery. Instead it seems that anaerobic digestion or combustion may be more appropriate. Given this situation, it may be more important to utilise strains of algae that are most suited to individual scenarios (wastewater type, climate etc.). It is also likely in many locations with climatic variation in seasons that the species of algae dominating will change as temperatures and amount of sunlight vary. There are examples of such species change in the literature, Professor Shelef in his study of algal cultivation in raw wastewater in open ponds found that in Spring Micratinium dominated, in Summer Chlorella was most common and in autumn and winter Euglena became dominant [23].

The alternative to allowing various strains to dominate naturally is to select a strain that is capable of tolerating extreme conditions or recycling the favoured algae. Spirulina is a species of algae renowned for good bio­mass control due to high pH requirements [111, 112]. Conditions could be manipulated to promote the growth of species such as Spirulina by adjust­ing pH in wastewater streams. In a study conducted by Olguin et al. [113]

Spirulina was cultivated in piggery wastewater and seawater. In the study, continuous cultivation of Spirulina was achieved with no issues relating to contamination. Calculations would be necessary to understand whether or not promoting specific strain dominance would be worthwhile from an energy recovery perspective. It may be more productive to simply allow a naturally dominant strain to develop requiring fewer inputs. As studied by Park et al. [91], it is also possible to recycle algae improving dominance of selected strains. This may provide a robust method of selectivity and could allow for improved productivity with little input required.

a Wastewater treatment plant; b Secondarily treated wastewater [104]; c Raw dairy manure [105]; dRaw swine manure [106]; e Bioethanol distillery [102], f Distillery stillage [107]; g Grape distillery [108]; h Brewery wastewater [109]; i [110].

The overall financial return on investment, FROI, can be calculated as:

(CC + OC + L)g + (CC + OC + L)p (CC + OC + L)r(CC + OC + L)d

(13)

where R is revenue (from bio-oil (BO), biomass fuel (BMF), and subsidies (S)), and the total investment is the sum of the capital costs (CC), operat­ing costs (OC), and labor costs (L) for growth (G), processing (P), refining (R), and distribution (D). To parallel the 2nd O EROI, the partial financial return on investment, PFROI, is defined as:

and is equivalent to the QA 2nd O EROI.

In Equation (14), RBO is revenue from bio-oil, RBMF is revenue from biomass fuel (methane), and OC is the operating cost for growth (G), pro­cessing (P), and refining (R). Capital, labor, fuel distribution, discounting, and potential subsidy revenue would need to be included to determine an overall FROI.

Coherence is a fundamental property of a quantum field in which coherent quanta give rise to an order extending over a long distance within which there is a finite probability of finding the system in this order-related state [100]. It is demonstrated in an organism by the movements that are fully coordinated at macroscopic to the molecular levels [90]. The metabolic functioning of living systems has revealed nanomechanical and electrical oscillations in the frequency range of 0.4 to 1.6 kHz, that were found in the yeast, S. cerevisiae using atomic force microscopy. If metabolic function was chemically inhibited, the oscillations ceased. It was concluded that the oscillations were consistent with cellular metabolism of molecular motors and may be part of a communication pathway or pumping mechanism by which the yeast cell supplements the passive diffusion of nutrients and/ or drives transport of chemicals across the cell wall [101-103]. Physical signal transmission were also found in bacterial cells, where growth-pro- moting/regulating phonons or sonic vibrations, were effectively transmit­ted over a distance of at least 30 cm in air, through 2.5 mm plastic barrier, as well as a 2 mm iron plate to distant cultures [104]. Further, sound waves generated from a speaker at specific frequencies promoted colony forma­tion under non-permissive stress conditions [105].

Remarkably, it has been found that even biological events tradition­ally considered chemically based, such as the lock-and-key model for ol­faction, may actually rely more fundamentally on quantum scale atomic processes of inelastic electron tunneling from the donor to a receptor for critical discrimination [106,107]. For example in photosynthesis, light en­ergy is ultimately transduced into chemical and electronic energy through the apparatus of the photosynthetic reaction center. Here the excitation of a chlorophyll molecule by the photon’s energy initiates a series of charge — transfer processes from the antenna pigments to the reaction center via quantum coherence energy transfer [108]. The first steps are so fast that quantum dynamics of the nuclear motion needs to be accounted for as well as electron tunneling [109]. The wave-like characteristics of this energy transfer can explain the extreme efficiency that allows the light harvesting complex to sample vast areas of phase space to find the most efficient path [110].

Most notably, it was discovered that all living biological systems emit ultra-weak photons, or biophotons, which exhibit very unique physical characteristics during spontaneous emission and delayed luminescence. The hyperbolic decay and oscillations of these electromagnetic emissions or biophotons, in the optical regime have been observed experimentally and are indicative of coherent emission in accordance with multimodal laser theory. Coherent electromagnetic radiation strongly suggests the ca­pacity for electromagnetic pathways in intercellular communication [111]. Groups of molecules cannot emit independently from each other because the distance between cells is smaller than the wavelength of the radiation they emit. Since they are coupled by a common radiation field, they will always be coherent [112]. Inside a coherent region or domain, energy trav­els in a wave-like fashion, whereas in non-coherent domains the energy propagates in a diffusive manner [72]. This coupling field consists of inter­ference patterns reflecting the structure of the antenna system, i. e., groups of molecules, to which it is feedback coupled. Any field has a coherence space-time in which coherent states may exist by having a region where the phase is defined. Outside this region, the phase information is lost, but within it, the interference patterns are formed and a particle loses its clas­sical pictures. Thus the particles and fields within the coherence region must be considered as an indivisible whole [112]. Gurwitsch first discov­ered coherent emission of ultraweak luminescence on the tips of onions roots in the 1920’s. Modern interpretations of biophotonics conceptualize organisms as biological lasers of optically coupled emitters and absorbers operating at the laser threshold. A technical systems such as a laser, has a fixed coherence region or volume, while organisms may have a multitude of different coherence volumes, which can exist simultaneously and can overlap and demonstrate dynamic properties. The physical components of an organism is coupled with what can be described as a highly coherent, holographic, biophoton field, which has been proposed to be the basis of biological communication at all levels of organization. The components of the organism are seen to be connected in such a way by phase relations of the field that they are instantly informed about each in real-time. The coherent states appear to be fundamental for biological systems since they enable optimization of organization, information quality, pattern recogni­tion and regulation of biochemical and morphogenetic processes [112]. It has been proposed that enzyme dynamics are an outcome of the coher­ent electromagnetic structure of living systems. Enzymes exhibit selective interactions with specific molecules which strongly suggest the existence of a coherent medium since the molecules no longer interact through ran­dom collisions. Classically enzymes are depicted as chemical polymers, however upon applying quantum electrodynamics (QED) principles an enzyme is projected as a coherent domain of its component monomers bound by electrodynamic as opposed to chemical attraction [72].

In various biophotonic experiments with cultures of the unicellular alga Acetabularia acetabulum exposed to variety of influences such as varying salt concentrations, chloroform, and temperature modulation, it was concluded that the delayed luminescence was not solely a function of the primary delayed photochemical fluorescence events of the photo­synthetic apparatus. However, it demonstrated global correlations and in­formation about the organization of streaming motility of the chloroplast and the cytoplasmic structure of the cell [113]. The cytoskeleton is an important milieu for providing coherent events being the basis for acous — tic/photonic transmission. In established A. acetabulum cultures the indi­vidual cells form extensive electromechanical interactions where phase boundaries and mechanical tensions play an important role, which may be closely connected with biochemical changes and ultimately in a collective biophoton emission pattern [114].

In addition to lipids, microalgae can produce some value-added bioactive substances, such as polysaccharides, proteins and pigments. Therefore, microalgae have good prospects in the food, feed, pharmaceutical, and cosmetic industries. If a biorefinery approach that converts microalgae to wide range of products including biodiesel and value-added products, it will significantly improve the economic outlook of microalgae based fuels production.

1.7 CONCLUSIONS

Microalgae are a sustainable energy resource with great potential for CO2 fixation and wastewater purification. This review discusses current status and anticipated future developments in the microalgae to biodiesel approach. For biodiesel production to have a significant impact on re­newable fuels standards, technologies must be developed to enable large scale algae biomass production. The strategies for both high biomass and lipid productivities are discussed. Further efforts on microalgae biodiesel production should focus on reducing costs in large-scale algal biomass production systems. Combining microalgae mixotrophic cultivation with sequestration of CO2 from flue gas and wastewater treatment, and taking the biorefinery approach to algal biomass conversion will improve the en­vironmental and economic viability.

Hoogwijk performed a study on potentials of renewable energy sources, including an assessment of the increase in land use for the built environ­ment [3]. Current land use for the built environment was estimated to be 2% of the total global land mass excluding Antarctica. United Nations projections estimate this land use to be 4% in 2030 [19].

We therefore assume that land use for the built environment will in­crease from the current 2% to 4% in 2030. We extrapolated this figure, using the population growth numbers used throughout the Ecofys Energy Scenario, to a 5% land use in 2050. The growth from current to 2050 land use for the built environment therefore requires excluding 3% of global land mass, excluding Antarctica, for this purpose.

Next, we have assumed that all of this expansion will take place on unprotected grass — and woodland because expansion into other land types is either not possible, not acceptable or much less likely. 3% of the global land mass, excluding Antarctica, amounts to 12% of the unprotected grass and woodland. We have therefore reduced the land potential for rain-fed cultivation of energy crops by 12% for human development.

The reduction then totals 1,040,000 km2 (104 million hectares). This reduction is additional to the exclusion of urban areas based on IIASA data.

Based on this analysis and consistent with some earlier research, there are a few approaches and areas of opportunity where innovations would make the biggest impact in terms of improving the energy balance, economic profitability, and water intensity of algal biofuel production. These im­provements include:

1. using waste and recycled nutrients (e. g., waste water and animal waste) [11,15,25-28,65,71,72];

2. using waste heat and flue-gas from industrial plants [44,59], car­bon in wastewater [28], or developing energy-efficient means of using atmospheric CO2;

3. developing ultra-productive algal strains (e. g., genetically modi­fied organisms) [73-75];

4. minimizing pumping [58,76,77];

5. establishing energy-efficient water treatment and recycling meth­ods [55];

6. employing energy-efficient harvesting methods, such as chemical flocculation [66,78,79], and

7. avoiding separation via distillation.

The development of genetically modified organisms that secrete oils might provide parallel reductions in energy expense, as the oil might be more easily collected. Policies (e. g., carbon legislation) and externalities could change algal biofuel economics, but not energy accounting. Addi­tionally, algae can produce nutraceutical and pharmaceutical co-products, which could significantly improve the overall process economics. For comparison, co-products account for approximately 20% of the energy value for corn ethanol [13]; because co-products from algae find markets in higher value industries, algal fuels will likely have higher co-product al­location than from corn seed. The most favorable scenario for algal biofuel production is one that can use each of the improvements listed above. Im­plementing growth and processing technology advancements, in conjunc­tion with co-locating facilities with discounted energy and materials (i. e., electricity plants, waste water treatment plants, livestock feed lots, etc.) offers the potential for profitable algal biofuel production, and this concept has been proposed by several researchers [11,15,25,26,28,44]. However, relying on waste materials as feedstock relegates algal biofuel production to relatively low volumes [11,28,71].

Overall, it is most important that the EROI for the energy sector is greater than unity, including contributions from all energy resources. Al­though the results of this study suggest that the EROI for algal fuels will remain less than one without significant biotechnology innovations, algae represent one of the few alternative feedstocks capable of producing pe­troleum fuel substitutes directly (without expensive gasification or Fisch — er-Tropsch processes) for applications that require high energy-density, such as aviation. Thus, even though algal biofuels face significant hurdles before becoming large-scale substitutes for petroleum, they have the po­tential to satisfy niche markets in the short-term, while implementation of “game-changing” biotechnology advances are needed for sustainable large-scale algal biofuel production.

When looking forward towards those potential advances, it is the au­thors’ hope that the analytical approach presented in this manuscript will provide a useful framework with which progress can be tracked. Specifi­cally, we think this framework will be useful for tracking energy, cost, water and other resource inputs and outputs of cultivation.