Excellent article.

In the debate Food Vs Fuel,fortunately there are alternatives like Agave and Opuntia for Corn and Sugarcane as biofuel.

According to Arturo Velez, Agave Expert:

“On an annualized basis agave produces 3X more distilled ethanol than sugar cane in Brasil; 6X more distilled ethanol than yellow corn in the US; at least 3X more cellulosic ethanol than switchgrass or poplar tree. Producing one gallon of distilled ethanol from agave costs at the most half the cost of one gallon from sugar cane and one fourth of corn’s production cost.

One hectare of Agave captures at least 5X more CO2 than one hectare of the fastest growing Eucalyptus on a high density plantation and in one single year agave produces the same cellulose pulp Eucalyptus produces in 5 years”..

CAM species such as Agave show considerable promise as a biofuel crop for the future due to their high water-use efficiency, tolerance to abiotic stress (e.g., drought and high temperatures), and potential for high biomass production on marginal lands .

The optimal use of water to grow a selected feedstock is of critical importance because water scarcity, more than any other factor, determines whether land is suitable for growing food crops. Thus, growing plants with high water-use efficiency on land that is too dry to grow food crops is a potentially powerful strategy for producing biomass feed stocks in large amounts while minimizing competition with the food supply. Additionally, making productive use of semi-arid land can have positive effects on poor rural areas. The water-use efficiency (WUE) value (grams CO2 fixed/kilogram water transpired) varies markedly among plants with different types of photosynthetic metabolism. C3 plants typically have WUE values of 1–3; C4 plants, between 2 and 5; whereas crassulacean acid metabolism (CAM) plants have values between 10 and 40. Therefore, CAM plants can be cultivated in arid or semi-arid land normally unsuitable for the cultivation of most C3 and C4 crops. It is exceedingly unlikely that a C3 or C4 plant could be developed, with or without genetic modification, with water-use efficiency approaching that of CAM plants.Moreover, CAM plants are native to essentially every state in the USA except Alaska, although they are prominent parts of ecosystems only in the Southwest.

In spite of this potential, CAM plants have received much less systematic study or development as energy crops relative to inherently less water-efficient plants such as corn (maize), sugarcane, switch grass Miscanthus, poplar, sugar beets, Jatropha, soy, and canola.

Cellulose content is far more in Agave Americana compared to Deciduous Wood,sugarcane,wheat straw,corn stover and switch grass while lignin content is far less in Agave Americana as compared to the others mentioned.

A group of Mexican researchers believe they’ve discovered what they call the «missing energy crop,» and though it hasn’t exactly been missing-it grows abundantly in Mexico and in some southern U.S. and South American locations-these scientists claim agave possesses characteristics superior to other feedstocks currently being examined for biofuel purposes, such as cellulosic ethanol production.

Agave is arguably one of the most significant plants in Mexican culture. It has a rosette of thick fleshy leaves, each of which usually end in a sharp point with a spiny margin, and is commonly mistaken for cacti.

President Barack Obama’s Plan to tackle Climate Change includes,” The US will increase its research and development of bio ethanol as fuel. I believe biomass and ethanol are a part of the solution and belong in the green transition. Yet bio fuels and ethanol are many things. Not all are green and not all are sustainable in the broadest sense. For bio ethanol to belong in the green economy it has to deliver substantial greenhouse gas savings and avoid negative impact on food prices. Only then will it be good business for farmers and good for the climate. The technology is available and ready to be scaled up. Second generation bio ethanol is an emerging market with the potential to reduce 85 pct. of CO2 emission compared to regular fossil fuels in transportation. It is also a local resource increasing energy independence and creating local jobs in agriculture, factories and logistics.”. It is most welcome.

Hitherto Corn and Sugarcane are used in the biofuel production. In the debate on FOOD Vs FUEL, it is necessary to find alternatives.

“Agave has a huge advantage, as it can grow in marginal or desert land, not on arable land,” and therefore would not displace food crops, says Oliver Inderwildi, at the University of Oxford. The majority of ethanol produced in the world is still derived from food crops such as corn and sugarcane. Speculators have argued for years now that using such crops for fuel can drive up the price of food.

Agave, however, can grow on hot dry land with a high-yield and low environmental impact. The researchers proposing the plant’s use have modeled a facility in Jalisco, Mexico, which converts the high sugar content of the plant into ethanol.

The research, published in the journal Energy and Environmental Science, provides the first ever life-cycle analysis of the energy and greenhouse gas balance of producing ethanol with agave. Each megajoule of energy produced from the agave-to-ethanol process resulted in a net emission of 35 grams of carbon dioxide, far below the 85g/MJ estimated for corn ethanol production. Burning gasoline produces roughly 100g/MJ.“The characteristics of the agave suit it well to bioenergy production, but also reveal its potential as a crop that is adaptable to future climate change,” adds University of Oxford plant scientist Andrew Smith. “In a world where arable land and water resources are increasingly scarce, these are key attributes in the food versus fuel argument, which is likely to intensify given the expected large-scale growth in biofuel production.”

Agave already appeared to be an interesting bio ethanol source due to its high sugar content and its swift growth. For the first time Researchers at the universities of Oxford and Sydney have now conducted the first life-cycle analysis of the energy and greenhouse gas (GHG) emissions of agave-derived ethanol and present their promising results in the journal Energy Environmental Science.

On both life cycle energy and GHG emissions agave scores at least as well as corn, switch grass and sugarcane, while reaching a similar ethanol output. The big advantages agave has over the before mentioned plants is that it can grow in dry areas and on poor soil, thus practically eliminating their competition with food crops and drastically decreasing their pressure on water resources.

Plants which use crassulacean acid metabolism (CAM), which include the cacti and Agaves, are of particular interest since they can survive for many months without water and when water is available they use it with an efficiency that can be more than 10 times that of other plants, such as maize, sorghum, miscanthus and switchgrass. CAM species include no major current or potential food crops; they have however for centuries been cultivated for alcoholic beverages and low-lignin fibres.

They may therefore also be ideal for producing biofuels on land unsuited for food production.

In México, there are active research programs and stakeholders investigating Agave spp. as a bioenergy feedstock. The unique physiology of this genus has been exploited historically for the sake of fibers and alcoholic beverages, and there is a wealth of knowledge in the country of México about the life history, genetics, and cultivation of Agave. The State of Jalisco is the denomination of origin of Agave tequilana Weber var. azul, a cultivar primarily used for the production of tequila that has been widely researched to optimize yields. Other cultivars of Agave tequilana are grown throughout México, along with the Agave fourcroydes Lem., or henequen, which is an important source of fiber that has traditionally been used for making ropes. The high sugar content of Agave tequilana may be valuable for liquid fuel production, while the high lignin content of Agave fourcroydes may be valuable for power generation through combustion.

Along with Agave species described above, some other economically important species include A. salmiana, A. angustiana, A. americana, and A. sisalana. Agave sisalana is not produced in México, but has been an important crop in regions of Africa and Australia. Information collected here could thus be relevant to semi-arid regions around the world.

Agave is a CAM Plant. Crassulacean acid metabolism, also known as CAM photosynthesis, is a carbon fixation pathway that evolved in some plants as an adaptation to arid conditions in a plant using full CAM, the stomata in the leaves remains shut during the day to reduce evapotranspiration, but open at night to collect carbon dioxide (CO2). The CO2 is stored as the four-carbon acidmalate, and then used during photosynthesis during the day. The pre-collected CO2 is concentrated around the enzyme RuBisCO, increasing photosynthetic efficiency. Agave and Opuntia are the best CAM Plants.

Agave Competitive Advantages

* Thrives on dry land/marginal land. Most efficient use of soil, water and light

* Massive production. Year-around harvesting

* Very high yields with very low or no inputs

* Very high quality biomass and sugars

* Very low cost of production. Not a commodity, so prices are not volatile

* Very versatile: biofuels, byproducts, chemicals

* World-wide geographical distribution

* Enhanced varieties are ready.

Agave can be grown in huge areas of waste lands in Developing countries like India. Another route of power production is biogas generation from Agave as well as Opuntia. Biogas power generators are commercially available. This way power can be generated at local level with local resources. Both agave and Opuntia are regenerative plants.

In their research paper SARAH C. DAVIS et al conclude:

«Large areas of the tropics and subtropics are too arid or degraded to support food crops, but Agave species may be suitable for biofuel production in these regions. We review the potential of Agave species as biofuel feedstocks in the context of ecophysiology, agronomy, and land availability for this genus globally. Reported dry biomass yields of Agave spp., when annualized, range from 1 to 34Mg /ha/yr without irrigation, depending on species and location. Some of the most productive species have not yet been evaluated at a commercial scale. Approximately 0.6Mha of land previously used to grow Agave for coarse

?bers have fallen out of production, largely as a result of competition with synthetic ?bers.

Theoretically, this crop area alone could provide 6.1 billion L of ethanol if Agave were reestablished as a bioenergy feedstock without causing indirect land use change. Almost one-?fth of the global land surface is semiarid, suggesting there may be large opportunities for expansion of Agave crops for feedstock, but more ?eld trials are needed to determine tolerance boundaries for different Agave species(The global potential for Agave as a biofuel feedstock, GCB Bioenergy (2011) 3, 68–78, doi: 10.1111/j.1757-1707.2010.01077.x).»

Agave and Opuntia are the best choice to grow in waste and vacant lands in Asia,Africa and Latin America.The advantage with the plants is both are regenerative and thrive under harsh conditions.

Another plant of great use is OPUNTIA for biofuel / biogas production.

The cultivation of nopal((OPUNTIA FICUS-INDICA), a type of cactus, is one of the most important in Mexico. According to Rodrigo Morales, Chilean engineer, Wayland biomass, installed on Mexican soil, “allows you to generate inexhaustible clean energy.” Through the production of biogas, it can serve as a raw material more efficiently, by example and by comparison with jatropha.

Wayland Morales, head of Elqui Global Energy argues that “an acre of cactus produces 43 200 m3 of biogas or the equivalent in energy terms to 25,000 liters of diesel.” With the same land planted with jatropha, he says, it will produce 3,000 liters of biodiesel.

Another of the peculiarities of the nopal is biogas which is the same molecule of natural gas, but its production does not require machines or devices of high complexity. Also, unlike natural gas, contains primarily methane (75%), carbon dioxide (24%) and other minor gases (1%), “so it has advantages from the technical point of view since it has the same capacity heat but is cleaner, “he says, and as sum datum its calorific value is 7,000 kcal/m3.

Javier Snchez et al in their extensive study on Opuntia as potential input for bioethanol concluded:

“Prickly pear is a widely-known crop in the SE of Spain, where it is currently used for forage, fodder and fruit. Now it is being considered as a potential crop for bioethanol production from its whole biomass. In order to estimate the potential bioethanol production in the province of Almeria (SE-Spain) and the optimal location of bioethanol processing plants, a GIS analysis involving a predictive yield model of prickly

pear biomass was undertaken following specific restriction criteria. According to this analysis, the total potential bioethanol production in Almeria would be up to 502,927.8 t dm•year–1 from 100,616 ha maximum that could be cultivated with prickly pear, with a calculated yield ranging between 4.2 and 9.4 t dm•ha–1•year–1. An exclusive suitability analysis and a preferable suitability analysis based on the

Analytic Hierarchy Process were performed in order to estimate the optimal location of the subsequent processing plants within Almeria’s road network by a discrete location-allocation model.”(Javier Snchez , Francisco Snchez , Mara Dolores Curt Jess Fernndez (2012) Assessment of the bioethanol potential of prickly pear (Opuntia ficus-indica (L.) Mill.) biomass obtained from regular crops in the province of Almeria (SE Spain), Israel Journal of Plant Sciences, 60:3, 301-318).

In the developing countries like India which has vast waste land Opuntia can be grown along with Agave for Biofuel/Biogas and subsequent power generation.

Corn ethanol, for example, has an energy balance ratio of 1.3 and produces approximately 300-400 gallons of ethanol per acre. Soybean bio diesel with an energy balance of 2.5, typically can yield 60 gallons of bio diesel per acre while an acre of sugar cane can produce 600-800 gallons of ethanol with an energy balance of 8.0. An acre of poplar trees can yield more than 1,500 gallons of cellulosic ethanol with an energy balance of 12.0, according to a National Geographic study published in October 2007.

Dr.A.Jagadeesh Nellore(AP),India

E-mail: anumakonda.jagadeesh@gmail.com