Introduction

A major global concern today is that one in seven people today do not have access to sufficient protein and energy in their diet and several more suffer from micronutrient malnourishment as well (FAO 2016; Godfray et al. 2010). Burgeoning population with an increase in the wealthy and their higher purchasing power are instrumental in emerging scenario of conspicuous consumption patterns, more production of processed food, meat, dairy and fish, all cumulatively exerting tremendous pressure on basic food production systems. The food producers are experiencing increasing competition for land, water and energy while intensive agriculture, livestock ranging and increasing reliance on aquaculturing systems for fish, shrimp etc. pose seemingly unsolvable problems on the quality of land, water and air. Godfray et al. (2010) explicitly stated the world in the throes of a threefold challenge:
(i) Matching the rising demand for food from a large and more affluent population to food production and supply systems.
(ii) Evolving environmentally and socially sustainable production and supply processes.
(iii) Ensuring that world’s poorest people are not hungrier and are wholesomely fed.
In the absence of addressing these challenges, about 2 billion of the global population of over 7 billion will face severe food crisis (Wheeler and Braun 2013). In India large fragment of the population suffers with burgeoning population from under nutrition, unplanned urbanisation, increased consumerism (by few with their higher purchasing power) are instrumental in emerging scenario of conspicuous consumption and shifting patterns to more hig hvalue (50% increase by 2030) agricultural commodities (Wheeler and Braun 2013) and production of processed food, meat, dairy and fish, etc. These would cumulatively exert tremendous pressure on the sustainability of natural resources. India with the score of 28.5 ranks at 97 among 118 developing countries on Global Hunger Index (2016) compared to counterparts Nepal (GHI score 21.9 ranking 72) and Bangladesh (GHI score 27.1 ranking 90). This highlights the widespread persistence and prevalence of food insecurity due to lack of vision in the planning process. Overcoming malnutrition and hunger in the 21^st century necessitates adequate quantity of quality food, and transforming food production systems with the sustainable, efficient an environmentally safer processes (Braun 2007).
Along with food, energy plays a very pivotal role in the welfare of the society. A country’s prosperity and welfare depends on the accessibility to reliable and secure supply of energy in any form - oil, gasoline or electricity (Oh et al. 2010). Perishing stock of fossil fuels with higher GHG (Greenhouse gas) footprint and increasing CO₂levels in the atmosphere to alarming levels have contributed to changes in the climate in the planet. According to International Energy Agency, Global energy consumption is estimated to increase 53 percent by 2030, with 70 percent of the demand from developing countries. Exploitation of natural resources andconsumption of large amounts of fossil fuels have resulted in the production of toxic waste, pollutants, endangering flora and fauna with increased global warming. This has necessitated exploration of technically feasible, economically aviable, socially acceptable and environmentally sound energy alternatives to complement or replace fossil fuels (Ramachandra and Deepthi 2016; Posten and Schaub 2009; Borines et al. 2011; Kumar and Sahoo 2012). The current research focusses on the prospects of biofuel from algae.
Algae form the diverse group of organisms, due to their morphotypes, cellular structures, and their proportion ranging from several cm to tens of meters (Misurcova 2011). The macroalgae, occurring in greater abundance in seas and oceans, commonly known as seaweeds, are macroscopic multicellular marine algae, broadly categorised in to three groups based on the colour of the pigment; viz. Green, Red and Brown algae. These group contain specific polysaccharides (agar, algin, and carrageenan) and phytochemicals (sulphated polysaccharides, polyphenolic compounds and antioxidant enzymes) missing in terrestrial plants (Pereira and Neto 2014).
In conformity with the Declaration by world summit to meet target of (FAO 2015) 70 percent more food by 2050 and on framing policies towards substantial reduction (Kyoto protocol 5.6% by the year 2012) in GHG emissions through increased introductions of renewable as well as more sustainable biofuels the search is already on for sourcing such fuels from marine macroalgae or seaweeds, which are hitherto underexplored, but abundantly available and often cultivable (Tester and Langridge 2010; Forster and Radulovich, 2015).
Seaweed polysaccharides are extensively used as thickening agents in sweet and savoury sauces and condiments, to stabilise food products against degradation, staling and heating or cooling/freezing, also used as fat replacers in a range of food applications (Forster and Radulovich 2015). The market price of one of the phytochemicals, carrageenan was estimated to be $720.3 million in the year 2013, at 5.3 percent rise annually which is projected to reach $931.6 million by the end of 2018.
Carrageenan accounts for 13.3 percent share of the global food and beverage hydrocolloids market. These phytochemical compounds form a part of healthy balanced diet. While protein content of seaweeds is higher than other food materials (Table 1) such as cereals, eggs and fish they are also excellent sources of vitamins A, Bl, B12, C, D and E, riboflavin, niacin, pant acid and folic acid as well as minerals such as Ca, P, Na, K. The known uses of seaweeds as food, date back to 300 C in China and Japan (Ortiz et al. 2006; FAO 2009; Collins et al. 2016) and these countries are still in the forefront of seaweed cultivation, and consumption in the world. Seaweed variants have been successfully included as an ingredient in the number of food applications. Dried seaweed is high in dietary fibre, along with a range of other potentially bioactive components, its addition has the potential to enhance the nutritional quality of a product (Kim et al. 2008). The pharmaceutical industry is evincing considerable interest in seaweed phytochemicals towards development of novel drugs. Seaweeds antioxidant capability is verified which protect the human body from free radicals and retard the progress of many chronic diseases such as hypertension, heart diseases, diabetes and cancer (Kokabi et al. 2013; Kolanjinathan et al. 2014; Collins et al. 2016). Though the current utilisation of seaweeds, in terms of global food production, is on a very modest scale, they are recognized as wholesome, healthful, and tasty foods.

Table 1: Nutritive values of some seaweeds in relation to cereals and pulses (in percent)
References: ¹Forster and Radulovich 2015;²Haard 1999; ³ Koehler and Wieser 2013, ⁴ FAO 2016, ⁵Ramachandra and Deepthi 2016

Food Security

Seaweeds are readily available food sources that have been consumed by coastal communities, particularly in Asia (Table 2), may be from pre historical times. Their popularity through centuries, especially in East and South-east Asian cuisine, has captured global attention and currently seaweed based dishes adorn the menu of most of Europe and America. If tastier, easy to prepare, and moderately priced seaweed products become a reality in rest of Asia and in the West, certainly the seaweeds stand great potential as important component of the world’s vegetable diets, embarking a flourishing seaweed farming industry in the imminent future (Forster and Radulovich 2015). Such developments would herald a new era of greater certainty in supplementing or augmenting our existing food supplies, most based on irrigated crops, livestock, and cultured fishery, at great cost to environment and collectively leaving behind enormous carbon foot prints. Seaweeds also provide an edge against possible crop failures.

Table 2: World food production
References:Forster and Radulovich 2015; Ramachandra and Deepthi 2016; FAO 2016

There is a growing belief in coastal region that continued growth in aquaculture will automatically relieve pressure on depletion of wild fish stocks, allowing their populations to recover while supplying an ever-increasing demand for protein to nourish a growing human population. However current trends in the world aquaculture industry do not support such belief. Problems have been cropping up from increased feed input, with small oceanic fish for fish meal production bearing the brunt of heavy fishing pressure, while depleting the food source for other carnivorous fish such as tuna as well as for seals and dolphins. Despite rising appreciation of the role of mangroves in coastal ecology, paradoxically enough, 50 percent of world’s mangroves have been cleared for establishment of brackish water shrimp farming.
Against such a dismal backdrop, the prospects of seaweed cultivation (unlike shrimp or fish farming), raises a hopeful situation of a net gain, surpassing the constraints of shrimp farming, since seaweeds need nothing more than sunlight energy to convert water, carbon dioxide (available in surplus, as the planet’s greenhouse carbon-enriched atmosphere is threatening “ocean acidification” as well), and inorganic nutrients, into sugars that then provide the chemical energy and intermediaries to synthesize more complex carbohydrates, proteins, fats, and other organic nutrients (Kumar and Sahoo 2012). Nutrient upwelling process being closer to shores than open ocean seaweeds are mainly confined to continental shelves. Near-shore waters worldwide are over enriched with inorganic nutrients like nitrate and phosphates due to upwelling and terrestrial runoff causing algal blooms of both micro and macroalgae. Hence a study was undertaken on seaweeds along the coast of Uttara Kannada district towards the centre of Indian west coast in the highly productive and biologically rich Aghanashini estuary. Hundreds of families residing along the estuarine shores are dependent on the estuary for their livelihood through fishing, including collection of bivalves and capture of crabs, shrimp aquaculture and raising of salt tolerant rice crops and capture fishery in the traditional gazni rice fields. Mining of molluscan shells, salt production, sand removal, water transportation etc. are other enterprises associated with the estuary (Subash Chandran et al. 2012). Culturing of economically important seaweed resources, especially some of those already present in the estuary Table 3), could be a good option for harnessing additional resources while minimising the existing extractive pressure on the estuary.
In India, although seaweeds are seldom used for food, their cultivation as sources of raw material for phycocolloids industry is gaining importance. The present state of seaweed underutilisation can be changed through promotion of seaweed farming and popularisation of newer, nutrient rich foods to dispel hidden hunger latent in bulk of the country’s population. Seaweed-based enterprises, while generating more income and self-sustaining jobs for especially the farmers and fishers of the densely populated estuarine zone can be a promising economic activity particularly empowering womenfolk (Rao and Mantri 2006; Radhika and Gayathri 2014; Reddy et al. 2014), who are facing crisis as their traditional livelihood sources especially related to bivalve and shrimp fishery, drying and trade, are getting out of gear due to a host of detrimental and exhaustive commercial uses of estuary beyond their control. Seaweed cultivationin estuarine region and processing can emerge as a less taxing but more promising alternatives to redeem the currently emerging bleak situation, which has, has obviously afflicted most other estuaries of the Indian west coast already. Seaweed cultivation is less demanding as regards resource and manpower inputs are concerned unlike organizing fishing and other agricultural activities. Seaweeds based foods could turn out to be more affordable and promising in future, at least in the coastal zones. Highvalued seaweed species has promising potential markets in Europe, USA, Japan etc. Consumption of certain algae (Undaria or Sargassum of marine and Spirulina of fresh water sources) is associated with decreased rates of HIV infection (after controlling for important covariates) (Teas et al. 2004). Improvements in farm efficiency and techniques related to seawards can bring to the doorsteps easily affordable and nutritionally rich seaweed products. Seaweed cultivation is in its formative and experimental stage in India, initially seaweeds were over exploited from natural resources, depleting the supply of raw materials. In order to stop this, edible and pharmaceutically important seaweeds such as Enetromorpha and Ulva and economically important seaweeds such as Sargassum, Cystoseira and Hypnea, Gelidiella and Gracillaria were attempted at large scale cultivation (Rao and Mantri 2006; Chanakya et al. 2012; Reddy et al. 2014).

Table 3: Current uses of seaweed species found in Aghanashini Estuary

Energy Security

Renewable energy has been making strident progress in India in recent times (Garg 2012; TERI 2010; Ramachandra and Ganesh 2015), evident from the fivefold renewable grid capacity increase in a span of 8 years (2002-2010) compared to European Union (EU) and USA. This growth is largely based on thermal energy, with other sources making important contributions. The conventional sectors are starting to face problems such as mining an import of coal, logistics and transportissues, limited extractable coal reserves and other environmental and climate change threats making project clearances difficult to obtain.
Biomass based energy accounts roughly for a quarter of India’s energy consumption, by far the largest share of which is the traditional use of biomass for cooking in households (Fig. 1). Largest share of biomass such as Bagasse (a by-product of sugarcane processing) have been utilized for 7 GW of power generation capacity in 2014 (Briol 2015; Ramachandra and Hegde 2015; TERI 2010), and a smaller share is cogeneration based on other agricultural residues. Other biomass based energy such as syngas and small scale thermal gasifiers are obtained via a range of gasification technologies.

Fig 1. Primary fuel energy demand in India

Fi g. 2. General schemati c of bioethanol from Seaweeds

The Indian Peninsula, enveloped by an extensive coast line from Kutch to Cape Comorin and beyond into the Sunderbans (apart from the coasts of Lakshadweep and Andaman and Nicobar Islands), has immense potential for seaweed production. In earlier reports (Reddy et al. 2014) a standing crop of 258,715 tons wet weight of seaweeds has been estimated from the intertidal and shallow sub-tidal waters of India. A total of 60 commercially important seaweeds have been recorded from Indian waters. Their current utilisation is mainly confined to production of commercially and industrially important phycocolloids. Raw materials are harvested manually, bringing additional source of income to over 10,000 coastal fisher folks (Reddy et al. 2014). Seaweed farming in India is currently in its infantile stage is poised for a due to primitive measures for cultivation and harvest strategies for sustainable production and utilization.The Central Marine Fisheries Research institute (CMFRI) of India has developed and perfected techniques for culturing Acanthophora spicifera Gelidiella acerosa, Gracilaria edulis and Hypnea musciformis, and now attempts are being made to find improved techniques for propagation and large scale culture of other economically important seaweeds. The Pepsi Foods Ltd. (PFL) has initiated cultivation of Kappaphycus alvarezii, an exotic seaweed, along a 10 km stretch of the Palk Bay side towards Mandapam in Tamil Nadu, with technical support from Marine Algal Research Centre, CSMCRI, Mandapam.The pecies is cultivated in 100 hectares through a contract farming system in which seaweeds are grown in individual plots of 0.25 ha (40 mx 60 m). Each harvest cycle takes 45 days with an annual yield of 100 tons (wet weight) per hectare, which makes 10 tons of dry seaweedenough for production of 2.5-3 tons of carrageenan (Radhika and Gayathri 2014; Reddy et al. 2014). The company has ambitious plans for expansion of seaweed cultivation. The seaweed industry is certainly on its way towards establishing itself well in India, for mainly production of agar and algin.
Recent research progress in India has unravelled the potential of the green seaweed Enteromorpha compressa in curing various types of allergies (Ramachandra and Deepthi 2016; Raoand Mantri 2006). Algal Enteromorpha is an edible alga successfully being cultivated in Okha, Gujarat. E. intestinalis was selected as a source of carotenoid for inclusion in the formulated diet of shrimp Penaeus monodon. In the Sundarbans, its cultivation is undertaken mainly for use as mineral rich manure. Nutritionally Ulva is a rich source of iodine, aluminium, manganese, magnesium, sodium, potassium, copper, zinc, trace elements and ash. It is high in iron (15 times greater than egg yolk) and calcium. Rich in protein is comprised of all 9 essential amino acids including Lysine which is the amino acid that is typically deficient in most vegetarian diets. It is rich in vitamins and antioxidants. High concentration of Beta carotene makes consumption of Ulva good for eye, health and as antioxidant. Ulva can be eaten raw in salads but it also used in cooking, soups, with meats and fish (Forster and Radulovich 2015).
Introduction of Seaweed farming by integrated coastal management projects has been initiated in India to raise the socioeconomic status of coastal communities as well as to provide an alternative income for fisher folks. Small scale algal cultivation requires little technical knowhow and almost no start-up costs. Biofuel from seaweeds could be a potential source of renewable energy, without any taxing on farmland resources, and promises new vistas in the agricultural marketing scenarioof India. India, rich in seaweed diversity, has also suitable areas for mass cultivation. The Kharlands or gazani of Karnataka, bheris of West Bengal, gheris of Orissa, pokkali rice fields of Kerala are prospective areas for cultivation of appropriate seaweed species. In Aghanashini estuary, gazani fields were traditionally being utilized for cultivation of salt tolerant ‘Kagga rice’. After harvest of rice towards the end of south-west monsoon, the fields used to be flooded with the water from the rising tide of the estuary, and used for fishery purpose. Parts of this estuary is currently being utilized for especially shrimp culturing. These gaznis, during the post-monsoon are essential locations for seaweed cultivation, at least in small parts, with only beneficial output towards fishery as well. Algal cultivation during post-harvest season of fisheries offers promises to the local communities in attaining an alternative and a self-sustained income generating job (Ramachandra and Deepthi 2016).