Cellulosic Ethanol (Energy Security and Climate

Journal of Biofuels DOI : 10.5958/0976-4763.2016.00010.6

Vol. 7 Issue 2, July-December 2016 pp. 71-78

Cellulosic Ethanol (Energy Security and Climate Change Mitigation): A Review Akram A. Khan1*, Rahil Akhtar Usmani2, Md. Anis Anwar3 1

Professor, 2,3Research Scholar, Department of AEBM, Aligarh Muslim University, Aligarh, Uttar Pradesh, India (*Corresponding author) email id: *[email protected]; [email protected]; [email protected]

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ABSTRACT Greenhouse gases (GHGs) emission is the most talked about issue especially since last decade. The rising pressure to cut emission for maintaining the ecological balance creates immediate rush for understanding the carbon emission process and development of strategies for its mitigation. Transportation sector is one of the primary sources of emission because of gigantic consumption of petroleum fuels. It is the second largest emitter of GHG which gets accumulated in the atmosphere and a reason of global warming. The rising oil import is the second shortcoming which is associated with petroleum fuels. It is the primary cause of depletion in foreign exchange reserves and trade deficit. In this study, cellulosic ethanol has been considered as a solution for these problems because of its ability to blend with gasoline. After blending, it reduces emission and if produced domestically decreases fuel import dependency substantially. Keywords: Cellulosic ethanol, Transportation, GHGs, Climate change, Environment, Carbon cycle, Energy security

1. INTRODUCTION In this fast developing world, efficient transportation facility is crucial to assure the certainty in growth. As other sectors grow, transport sector also grows, as a result energy consumption by transport sector increases. Energy demand by transport sector is mainly fulfilled by petrol and diesel. Petroleum fuels are not ‘carbon neutral’ and emit huge quantity of carbon after combustion. So they can badly affect the climate system. A major quantity of petroleum fuels are imported from the gulf countries which is a root cause of current account deficit. To avoid these adverse effects, there is a need of shifting towards more sustainable transportation fuel. Ethanol, if used as a transport fuel, has the prospects to be a solution for these problems. It is used as an additive in gasoline since a long time, which in turn helps in combustion and improves the air quality by reducing particulate matter and GHGs emission. Ethanol from starch-based crops like corn in the United States of America and sugarcane in Brazil is known as conventional ethanol. It does not serve the purpose of sustainability in long run because it creates threat to the food security and has less than perceived benefits for environment. The primary reason behind unsustainability of conventional ethanol is its limited reduction in net GHGs emissions because it requires larger fossil fuel resources for their production [1,2]. Ethanol usually blended into petrol in small proportions is dependent on the blending mandates of the respective country, like in the United States of America there is 10%, and in India 5%, 10% and 20% in different time period depending on the national biofuel policy [3]. The production of ethanol in India is dependent on the molasses (a by-product of sugar manufacturing). Ethanol produced in India is also used for other purposes besides blending, like as in medicines, as a beverage and others. Only a fraction of total ethanol is available for blending. In that case, cellulosic ethanol, a residue biomass-based ethanol, could serve the purpose of sustainability by improving air quality which helps in climate change mitigation and improvement of current account deficit by reduction in crude oil imports. 2. GHGS, CARBON CYCLE AND CLIMATE CHANGE Gases which trap heat (outgoing infrared rays) are known as greenhouse gases (GHGs) [4]. The heat trapping property of these gases helps in maintaining the temperature of earth’s atmosphere and keep the earth warm IndianJournals.com

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Akram A. Khan, Rahil Akhtar Usmani, Md. Anis Anwar

which is necessary for sustaining life. Excess of these gases cause over warming of atmosphere known as ‘global warming’. GHGs diffuse in the environment and distribute equally all over the globe irrespective from the point of origin. So the emission from the United States of America, China or India (top three CO2 emitters) affect the whole world equally. These gases have large life span; they mix well in the atmosphere and get stuck into it from weeks to decades. The most common GHGs are CO2, CH4, N2O, O3 and CFCs (chlorofluorocarbon). CO2 is the most abundant gas among the GHGs that is 76% (transport, agriculture and industry combined). The cyclic flow of carbon between various abiotic and biotic factors of the environment is necessary for the proper and balanced functioning of earth’s ecosystem. Carbon released from fossil fuel combustion increases the quantity of carbon in carbon pool of the ecosystem which disturbs the carbon cycle, because the newly introduced carbon has no place to confiscate. Thus, it accumulates in the atmosphere and reacts with oxygen to form CO2 and with hydrogen to form CH4, which are the major part of GHGs. After industrial revolution, concentration of CO2 has been increased by 36%.Behind this rise in concentration, the main contribution comes from the combustion of fossil fuels [5] (Figure 1).

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Figure 1: Carbon cycle; Source: [6].

The upshot of this rising concentration of GHGs is climate change. It can be defined as ‘the statistical change in common patterns of temperature and precipitation over a time period which causes change in the pattern of weather. Sometimes, effect of climate change can be manifested in the form of heat waves, cold waves, unseasonal rains and snowfalls [7]. The damaging impact of climate change has already been started, and its severity will depend upon anthropogenic emissions [8]. The ‘warming of the climate system is unequivocal, as is now evident from observations of increases in global average air and ocean temperatures, widespread melting of snow and ice, and rising global average sea level’ [9]. There is an urgent need of corrective actions to be taken to reduce GHGs emission to the extent where its impact is minimum. Global GHGs emission must be reduced to 50–85% from level of 2000 by 2050 to keep warming in the range of 2.0–2.4°C (3.6–4.3°F) [9]. If not taken at proper time, there will be 40–110% growth in CO2 emission till 2030 which will cause 25–90% increase in the global mean temperature from the level of 2000 [9]. If the temperature increased by 2–11°F, it will raise the sea level by 7–23 in., whereas another report says that it will raise by 3–4 ft by the end of this century [8]. 72

Vol. 7 Issue 2, July-December 2016

Cellulosic Ethanol (Energy Security and Climate Change Mitigation): A Review

3. WORLD’S CO2 EMISSION BY TRANSPORT SECTOR The transport energy requirement is growing up by 2% rate per annum, and the highest rate of growth is found in the emerging economies. At present, the share of non OECD (Organization for Economic Cooperation and Development) region in the total emission is 36%, and it will increase up to 46% in 2030 [10]. Petroleum supplies 95% of the total energy used in world transport which is responsible for the 23% (6.3 Gt) of world CO2 emissions in 2004. The share of road transport in the emission is highest, that is 74% of total transport sector. For transport, the fast emissions growth was driven by emissions from the road sector, which has increased by 68% since 1990 and accounted for three quarters of transport emissions in 2013 [11] (Figure 2).

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Figure 2: World transportation CO2emission 1990–2012 (million tonne); Source: [12].

3.1 India’s CO2 Emission by Transport Sector India is a developing country with exponentially growing population and experiencing unprecedented growth. Transport sector is the largest consumer of petroleum product in India and consumes 70% of diesel and 99.6% of petrol [13]. If the current pattern of growth is continued, the total energy consumption in transport sector will rise by 14 times in 2031 from the level of 2001 [14]. The CO 2 emission growth rate was 5.7% per annum from 1950 to 2007, but in 2008, it rose with the rate of 8.1% from the previous year. And hence, India emitted 457 million metric tonnes of carbon in the atmosphere which made it world’s third largest CO 2 emitter. It emits this larger quantity of CO2 because power generation in the country is totally dependent on coal [15] while the transportation sector is totally petroleum based (Figure 3). 4. CELLULOSIC ETHANOL Cellulosic ethanol is produced from the novel technologies which uses cellulosic biomass, primarily agricultural residues as their feedstock material. The benefits offered by cellulosic ethanol gains considerable advantage over the conventional ethanol and gasoline because of these two factors. First, lignocellulose is the most abundantly found material on the earth’s surface. It is estimated that the world wide biomass production by land plants is 170–200×109 t and 70% is estimated as plant cell walls which contain lignocellulose [16]. Second, the energy Journal of Biofuels

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crops which are sometimes noted as the dedicated energy crops like Miscanthus, Switch grass and others can be grown on the marginal and degraded land without much application of input and care [2]. 4.1. Cellulosic Ethanol – An Option for Transport Sector Emission Reduction A large amount of GHGs are emitted from the transport sector. And hence, the potential for reduction is also large here. The blending of ethanol in petrol is an old practice which helps in efficient combustion and replaces tetra ethyl led (an anti-knocking agent) which pollutes the environment. Ethanol, when is used as a transportation fuel, emits lesser sulphur, carbon monoxide, particulates and GHGs [17]. After understanding the benefits of ethanol in blending, the use of ethanol in transportation sector is continuously rising and world fuel ethanol production has increased. It has increased three folds in the period of 2000–2007 from 17 billion litre to 52 billion litre which provides 1.8% of the world’s transport that is36 Mtoe (million tonne oil equivalent) out of a total of 2007 MTOE [18]. In 2014, the total fuel ethanol production of the world was 25 billion gallons, and in the United States of America, 14 billion gallons represent 10% of total oil demand of the United States of America (Figure 4).

Earth Policy Institute -

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Figure 3: India’s CO2 emission 1990–2012 (million tonnes); Source: [12].

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Figure 4: World fuel ethanol production, 1975–2012; Source:[19]. 74



At present, the cellulosic ethanol is not produced commercially and all the plants are in either demonstration or pilot phase. But very large quantity of cellulosic ethanol that is 16 billion gallons is mentioned in the Renewable Fuel Standard of Energy Independence and Security Act (2007) [20]. If the cellulosic ethanol industry established, it will produce jobs, decrease imports dependency and reduce GHGs emission. The optimism for the huge environmental benefits of cellulosic ethanol is based upon the fact that cellulosic biomass required lesser quantity of fossil fuel inputs in their production as compared with gasoline and conventional ethanol [21–23]. The more efficient emerging production technologies of cellulosic ethanol are very promising and show more than 100% emission reduction in some cases [10]. Its GHGs reduction potential provides it the status of clean fuel which is a key facet of its environmental sustainability and main reason for its identification as a major player in mitigating climate change.




However, there is a long debate among the researchers regarding their GHGs reduction potential. Variouslife cycle GHGs emission studies show different findings regarding thee mission from the cellulosic ethanol [24]. But most of them agreed upon one common point that is cellulosic ethanol has clear benefit over the corn ethanol and gasoline in terms of GHGs emission. The emissions from cellulosic ethanol would be around one-fifth of the emissions from the first-generation conversion of cereals or vegetable oils [3]. Comparatively, lesser emission from cellulosic ethanol is proved by the combustion analysis of cellulosic ethanol in comparison with other fuels for the same amount of energy. When 1 mega joule (MJ) of energy is released by combustion of cellulosic ethanol, it emits only 11 (gram CO2 equivalent) gCO2e, whereas the corn ethanol emits 37–64 gCO2e on per MJ of energy [25]. The emission from the gasoline is 95 gCO 2e/MJ of energy [21]. Thee mission from conversion of rice and wheat straw to ethanol is estimated at 21.6–23.1 gCO 2e/MJfuel [3]. The CO2 emission from cellulosic ethanol is 85% lower as from the gasoline [26] and depending on the production pathway studies, it is observed that in some cases net GHG savings is up to 80% as compared with fossil fuels [21]. The indirect land use change (iLUC) is the most crucial issue when we talk about the GHG reduction potential from the different biofuels because the benefits offered by the biofuels can be nullified if there is a large emission by the land use change. In case of the cellulosic ethanol, its carbon emission from forestry residues is 22 gCO2e/ MJ where it is notable that the residues cause no iLUC. This is much lower than the corn ethanol which emits 77–105 gCO2e/MJ in which 30 gCO2e/MJ is coming from iLUC (Figure 5). Further, the emission of GHGs from ethanol depend upon the factors like production pathway, feedstock material and the distance covered for its logistics by transportation [27]. Cellulosic ethanol has the potential to significantly mitigate GHG, but the results have been calculated just for the pilot/demonstration phase. The use of agricultural and/or forestry residues as cellulosic ethanol feedstock could significantly reduce emissions compared with the production and use of fossil fuels and corn ethanol because it does not cause direct or Iluc [21]. Further, the emission of GHGs can be considerably reduced because cellulosic biomass has lignin and other recalcitrant residues that can be burned to produce heat or electricity consumed in the ethanol production process [21,23]. So we can say that in general, the overall environmental performance of it depends on the effectiveness and sustainability of the whole supply chain. As a result, it is important to ensure a sustainable supply of energy for the conversion process through by-products and effective logistics handling for feedstock provision and ultimately its distribution. 4.2. Cellulosic Ethanol and Energy Security In the United States of America, there is 7% saving in oil imports after the10% blending of ethanol which is primarily corn ethanol [28]. The biomass inventory of the United States of America has the potential of 1.3 billion gallons of ethanol from its agro-forestry residues [29].The potential of cellulosic ethanol increase more in future for instance IEA (International Energy Agency)projects biofuels will provide 12 EJ/y of energy in transport sector in which 60% is cellulosic ethanol that represents 11% of total transport fuel in 2035 [30]. Further, supply potential of biofuels is very impressive & will increase to the extent of 26% of total transportation fuel in 2050 in blue map scenario of IEA. And 90% of this increase in biofuel is coming from the cellulosic ethanol [21].

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Figure 5: Gram CO2 equivalent emission for per mega joule of energy Source: Based upon the above mentioned studies.

For India, importance of cellulosic ethanol is immense because of many reasons. First, the rising import dependency to meet demand of crude oil. Second, being an agricultural country, there are plenty of agricultural residues which are a good source of lignocellulose. Various studies indicate the quantity of agricultural residues available in India like, Hiloidhari who calculated the crop residue as 686 MT [31]. Ravindranath reported the gross crop residue as 626.5 MT [32]. IREDA (Indian Renewable Energy Development Agency) estimated total crop residue as 350 MT [33]. MNRE (Ministry of New and Renewable Energy) calculated 120–150 MT of crop residue and forestry residue which is available for energy generation in India [34]. All the studies that are mentioned here used different methodologies for estimation and selection of crops for residue. But the common fact of all the studies is that India has plenty of residues, and if directed towards the cellulosic ethanol production, it can replace considerable magnitude of transport fuel. 5. CONCLUSIONS AND SUGGESTIONS The issue of climate change and energy security is crucial to be addressed. We need a solution which could meet the requirements of running the vehicles as well as reducing the emission. Ethanol has prospects of addressing these problems by working as an excellent transportation fuel after blending with petrol. The massive amount of emission from the transport sector can be controlled by replacing the petroleum fuels with ethanol. There is a high optimism observed in the projections of the agency like IEA which considered cellulosic ethanol as a tool for meeting targets of blue map scenario. However, at present, there is a huge debate on the GHGs reduction 76



potential of cellulosic biofuels. There are strong indications that after blending significant amount of reduction in CO2 emission are observed. This reduction could be improved further if the sustainability of supply chain and benefits from the co-products would be considered. As far as the feedstock is concerned, there are enough residues available in the world and in India to produce enough ethanol for replacement of a significant amount of gasoline. The quantity of feedstock could be raised further if the energy grasses which is grown on marginal or unused land is added in that category. If the cellulosic ethanol industry is established and grew, it could provide three way benefits. First, reduction in oil imports hence improvement in trade balance which will make us less vulnerable to supply shortage or oil price shock. Second, due to production from the natural resources, it is clean and carbon neutral and helps in climate change mitigation. Third, development of domestic industry which creates employment and wealth for indigenous people. What we need is a supportive infrastructure with financial support for research and development and create awareness among people regarding its environmental benefits.




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