Make sure you are including the full citation for your documents in your lit. review with a link.

## Summary

• To stack up the case of solar photo-voltaic against the energy derived from biofuels.

## Goals

• Exergetic comparison of PV cells and Biofuel energy.
• Examining the prime and most efficient biofuel crop.
• Understanding the agronomic involved.
• Maximizing the exergetic output of PV cells.
• Investigating different techniques of making PV cells more affordable.

## Net energy from cellulose ethanol from switchgrass

Source: Schmer, Marty R.."Net energy from cellulose ethanol from switchgrass" Proceedings of the National Academy of Sciences 105.2 (2008): 464-469.[1]

• Evaluation of switchgrass as a biofuel.
• Concerns –
1)energy efficiency and economic feasibility
2)Investigated agricultural input cost
3)biomass yield
4)estimated ethanol output
5)greenhouse gas emission
6)net energy results

• Findings
1)Switchgrass produces 540% more renewable energy than nonrenewable energy consumed.
2)94% lower greenhouse emission than gasoline.

• They considered fields on 10 farms for net energy economic evaluation so that they can eradicated the discrepancies that occur when small with similar agricultural inputs are under consideration.
• Study considers various agronomic practices
• States that biofuel from switchgrass produces 13.1MJ of energy for every MJ of petroleum input.

TAKE AWAYS

1)This paper will not only build the case for switchgrass to be used as a biofuel but will also help us what kind of location and what suitable agronomic practices must be followed to get the maximum yield.
2)Location of the farm was found out to be one of the deciding factor for the amount of ethanol yield ye can extract.


## Energy cost of rapeseed based biodiesel as alternative energy in china

Source: Chen, H., and G. Q. Chen."Energy cost of rapeseed based biodiesel as alternative energy in china" Renewable Energy 36.5 (2011): 1374-1378.[2]

• Evaluating energy cost of rapeseed as biofuel.
• Cost can be divided into 4 categories
1)Crop production
2)Transportation
3)Industrial conversion
4)Wastewater management

• This paper stated that 1ha of land produces 1.5 ton of biofuel. This comes to around 20 GJ of energy left after taking into factor the energy used in the production.
• It focuses on an in-depth analysis of rapeseed as a biofuel.
• It gives insights on how biofuel is processed from the crop harvest.
• Detailed classification of energy cost of each and every element that goes into making the final usable biofuel.
• Findings
1)Agricultural produce contributes to the lion share of total energy cost.
2)Rapeseed biofuel has a negative energy return owing to the low production of crop.


TAKE AWAYS

1)Considering the areas where the average yield of crop is more.
2)Less nitrogen based fertilizers as they account for the highest share of cost for the agricultural production.
3)We should consider locations where the crop is abundantly available or there is some scope for increasing production and the energy input for agricultural produce is minimum.


## Energy balances for biogas and solid biofuel production from industrial hemp

Source: Prade, Thomas, Sven-Erik Svensson, and Jan Erik Mattsson. "Energy balances for biogas and solid biofuel production from industrial hemp" Biomass and bioenergy 40 (2012): 36-52.[3]

• Paper states that hemp has higher energy yield than any other crop to obtain biofuel.
• It is less susceptible to pest infection which in turn reduces the overall input cost.
• 4 cases were considered
1)Combined heat and power from spring harvested baled hemp: Combustion heat is used for generating electricity and residential heating.
2)Heat from spring harvested briquetted hemp: Combustion heat is used for small scale residential heating.
3)CHP
4)Vehicle fuel autumn harvested chopped and ensiled hemp: Depicts biofuel used in vehicles.

• The first case was found out to be most efficient.
• The study found out that the maximum chunk of input energy that goes into producing the final hemp biofuel is for processing the biofuel.
• Advantages are less pesticide requirement, weed resistant, crop rotation is possible.

TAKE AWAYS

1)Areas where probability of pest infection is more, hemp cultivation is desirable and economic than other crops.
2)Net energy yield of hemp is also more than most of the crops.
3)Less maintenance.


## Improvements in Life Cycle Energy Efficiency and Greenhouse Gas Emissions of Corn-Ethanol

Source: Liska, Adam J.."Improvements in Life Cycle Energy Efficiency and Greenhouse Gas Emissions of Corn-Ethanol" Journal of Industrial Ecology 13.1 (2009): 58-74.[4]

• This paper focuses on the greenhouse gas emission from the corn based biofuel.
• It also discusses how in recent times the net corn production has increased and new ways have been found out to produce more energy efficient biofuel.
• They performed energy life cycle simulation and greenhouse gases assessments.
• The net energy ratio was found out to be ranging from a minimum of 1.29 to a maximum of 2.23.

TAKE AWAYS

1)In the pursuit of finding the best crop for biofuel, an improved life cycle energy efficiency is essential.
2)New technological advancements help us to reduce the energy we put into "seed-to-fuel" cycle hence improving the net energy ratio.
3)Improved version of biofuel indicates towards less greenhouse gas emission.


## Camelina Derived jet fuel and diesel: Sustainable advanced biofuels

Source: Shonnard, David R., Larry Williams, and Tom N. Kalnes. "Camelina Derived jet fuel and diesel: Sustainable advanced biofuels" Environmental Progress & Sustainable Energy 29.3 (2010): 382-392.[5]

• Builds the case for camelina.
• The paper discusses the biofuel alternatives to jet fuel and diesel.
• It also evaluates the life cycle greenhouse gas emission and compares it with conventional jet fuel and diesel.
• It's grown without giving much attention as it can sustain extreme temperature and doesn't require much inputs unlike other plants.
• Biofuel proved to be very cost effective when greenhouse gases are considered as a net minimum saving of about 67% was noted when using camelina based fuel.
• It was concluded that even though camelina based fuel was cost effective and reduced emission to a great extent, its performance and energy efficiency was almost the same when compared to conventional fuels.

TAKE AWAYS

Camelina poses a strong competition to other biofuel crops as the energy requirement for its life cycle is considerably less keeping its energy output the same as the conventional fuel.


## A life cycle assessment of biodiesel production from winter rape grown in southern Europe

Source: Gasol, Carles M.."A life cycle assessment of biodiesel production from winter rape grown in southern Europe" Biomass and Bioenergy 40 (2012): 71-81.[6]

• The paper states the benefit of biodiesel over diesel in terms of
1)Abiotic Depletion
2)Photochemical oxidation
3)Global warming potential

• This is a life cycle assessment of rapeseed in terms of different climate and net crop yield.
• The highest energy consumed during the life cycle is in transesterification and oil extraction which was found to be 25.22% and 21.30% respectively.
• The study found out that biofuel has a less impact on abiotic depletion and global warming potential.
• Putting the coproducts (glycerin) to use again reduces stress on the environment.

TAKE AWAYS

The reusability of the byproducts.


## Exergetic evaluation of biomass gasification

Source: Ptasinski, Krzysztof J., Mark J. Prins, and Anke Pierik. "Exergetic evaluation of biomass gasification" Energy 32.4 (2007): 568-574.[7]

• This paper focuses on biofuel which is in gaseous form.
• It states that most of the energy is lost during the process of gasification and hence wants to make this process more efficient.
• It suggests that by drying the gas may increase the exergetic value of the gaseous biofuel.
• It states in order to reach the maximum efficiency of gas biofuel the right amount of oxygen must be added to the gasifier.
• The data suggests that the exergic value of vegetable oil is greater than other biofuel sources like straw, wood, grass, sludge, manure.

TAKE AWAYS

1)Gasification of biofuel releases some energy into thin air while the process of gasification is in process.
2)This is not at all desirable when dealing with biofuels.


## Improvements in life cycle Energy Efficiency and Green House Gas Emissions of Corn Ethanol

Source: Liska, Adam J. "Improvements in life cycle Energy Efficiency and Green House Gas Emissions of Corn Ethanol " Journal of Industrial Ecology 13.1 (2009): 58-74.[8]

• Improved technologies to increase energy efficiency and profitability, ethanol production and co-product use
• Use of thermo-compressors for condensing steam ,increase reuse, thermal oxidizers for combustion of volatile organic compounds and efficient utilization of waste heat
• Estimating the values of co products formed – value analysis by substitution of value of the co-product with another component that is needed in their production .This method is called substitution method.
• The various energy values considered -thermal energy, fertilizer use, seed, drying, electricity, and conversion yield, total ethanol yield, coproduct credit- to estimate the performance and greenhouse gas emissions.
• The effects of climate, soil quality and access to irrigation is discussed.
• The use of nitrogen fertilizer and the required inputs are discussed along with the effect of tillage and agricultural practices to improve the efficiency.

This paper helps us in understanding the different input and output factors that need to be considered when evaluating the impact of biofuel.

## Improvements in life cycle Energy Efficiency and Green House Gas Emissions of Corn Ethanol

Source: Liska, Adam J.."Improvements in life cycle Energy Efficiency and Green House Gas Emissions of Corn Ethanol" Journal of Industrial Ecology 13.1 (2009): 58-74.[9]

• Improved technologies to increase energy efficiency and profitability, ethanol production and co-product use
• Use of thermo-compressors for condensing steam ,increase reuse, thermal oxidizers for combustion of volatile organic compounds and efficient utilization of waste heat
• Estimating the values of co products formed – value analysis by substitution of value of the co-product with another component that is needed in their production .This method is called substitution method.
• The various energy values considered -thermal energy, fertilizer use, seed, drying, electricity, and conversion yield, total ethanol yield, coproduct credit- to estimate the performance and greenhouse gas emissions.
• The effects of climate, soil quality and access to irrigation is discussed.
• The use of nitrogen fertilizer and the required inputs are discussed along with the effect of tillage and agricultural practices to improve the efficiency.

This paper helps us in understanding the different input and output factors that need to be considered when evaluating the impact of biofuel.

## Land usage attributed to corn ethanol production in United States: sensitivity to technological advances in corn grain yield, ethanol conversion and co-product utilization

Source: Mumm, Rita H.."Land usage attributed to corn ethanol production in United States: sensitivity to technological advances in corn grain yield, ethanol conversion and co-product utilization" Biotechnology for biofuels 7.1 (2014): 1.[10]

• This paper identifies the key supply variables and understand long term effects and interactions involving corn grain yield, ethanol processing and livestock feeding and how these factors affect the land area attributed to ethanol production.
• This papers also explores the net efficiency considering different plant configurations. A comparison study has been done to study the trends of the crops through the years.

## Life Cycle Assessment of Corn Grain and Corn Stover in the United States

Source: Kim, Seungdo, Bruce E. Dale, and Robin Jenkins. "Life Cycle Assessment of Corn Grain and Corn Stover in the United States" The International Journal of Life Cycle Assessment 14.2 (2009): 160-174.[11]

• To study the effects of continuous corn cultivation of corn grain and corn stover considering the current practices in agriculture
• The conditions affecting the performance of the corn grains.
• To study the environmental effects the corn production has two cropping systems have been considered-(1) crop produced for the grain (2) corn grown for Stover.
• Impact assessment was done in the fertilizer(N,P,K ) herbicides, insecticides, lime, diesel, gasoline, LPG, electricity usage .
• Sensitivity assessment of the two systems were done in terms of nitrogen usage and ammonia loss.
• The effect of no tillage and tilling the fields were studied and the results indicate that no tillage practices reduce the total fossil energy GHG emissions by about 50%
• The results indicate that corn stover has a lower impact on the environment than the corn grain in terms of total fossil energy,greengouse gases acidification. Planting winter crops and transitioning to a no tillage farming practice are ways to reduce these nitrogen losses from the soil.

## 2008 Energy Balance for Corn-Ethanol Industry

Source: Shapouri, Hosein. "2008 Energy Balance for Corn-Ethanol Industry". DIANE Publishing, 2011.[12]

This is a report by the United States department of agriculture which is based on the net energy balance of the corn ethanol producers that was done by conducting a survey of ethanol producing plants.This report goes on to investigate about how the net ethanol production has changed from an energy sink to a net energy gain in present. This paper goes on to explain about the about how the inputs and energy needs has been varying over the past two decades.The data has also been divided statewise. This data is useful to understand how the energy calculations are done and approximately what the energy needs of the system would be on an average.

## Current and potential U.S Corn Stover Supplies

Source: Graham, Robin Lambert."Current and potential U.S Corn Stover Supplies" Agronomy Journal 99.1 (2007): 1-11.[13]

• This paper gives an idea of Stover production, collection and supply estimation methods subjects to constraints like soil moisture constraints , wind and water erosion constraints,etc.
• Grain to stover mass – 1:1
• Constraints in stover collection
1. Equipment constraints:amount left in the fiels is a function of equipment used to collect the stover and condition of stover atleast 25% left in the field
2. Soil Moisture Constraints:if rainfed agriculture all stover to be left on the field to maintain soil moisture for the next crop.
3. Water and wind erosion constraints
• Collectable stover = total stover- max constraints
• Discusses different tilling practices

## Ethanol Production Using Corn, Switchgrass, and Wood; Biodiesel Production Using Soybean and Sunflower

Source: Pimentel, David, and Tad W. Patzek. "Ethanol Production Using Corn, Switchgrass, and Wood; Biodiesel Production Using Soybean and Sunflower" Natural resources research 14.1 (2005): 65-76.[14]

This paper talks about the average input energy required,and cost of production of switchgrass,wood and corn to create biofuels and the approximate amount of non renewable/fossil energy that needs to be expended for their generation.This paper aides in deriving data regarding input energy and output energy of the various processes.

## (1)The 2001 Net Energy Balance of Corn Ethanol And (2)The energy balance of corn ethanol: An update

This report gives an idea of the net energy balances of corn ethanol production with reference to

• Production of corn
• Energy to transport corn to ethanol plant
• Energy used to convert corn to ethanol and by products
• Energy used in ethanol distribution

This also gives an idea about energy requirements of farm by considering weighted average of data gathered from the states belonging to the corn belt. It also gives an idea about the products obtained and energy used in the dry milling and wet milling.

## Biomass Supply From Corn Residues: Estimates and Critical Review of Procedures

Source: Gallagher, Paul W., and Harry Baumes. "Biomass Supply From Corn Residues: Estimates and Critical Review of Procedures" USDA, Washington, DC, USA. [16]

• This paper gives a good picture about how the Stover output and costs are calculated.
• This also gives a clearer picture of the supply- demand of corn bio-crop and related parameters used in the estimations and calculations.
• The author goes on to explain about the handling costs ,farm costs,plant costs and net value of the corn stover.

This paper is useful to understand the related functions, energy and money that need to be spent on the corn crop growing farms.

## Agricultural Statistics

Source: Agricultural Statistics[17]

"Agricultural Statistics is published each year to meet the diverse need for a reliable reference book on agricultural production, supplies, consumption, facilities, costs, and returns." This is a good source to study the trends in corn crop through the last decade

## Exergy and CO2 Analyses as key tools for the evaluation of Bio-Ethanol Production

Source: Kang, Qian, and Tianwei Tan. "Exergy and CO2 Analyses as key tools for the evaluation of Bio-Ethanol Production" Sustainability 8.1 (2016): 76.[18]

Energy a thermo dynamic analysis technique. Exergy is defined as "exergy is the maximum work that can be produced when a heat or material stream is brought to equilibrium in relation to ref environment" ( Dewulf.J,2010) The analysis identifies the energy and exergy loses in a system which is usually used in a poly-generation System and as for mainly thermochemical pathways The biofuel generation is considered as more successful in an integrated plant of first and second generation. The thermodynamic efficiency of a system is

Ƞ =(Exergy of useful products )/(Input Energy)


For Lignocellulosic

Ƞ = (Exet+Pnet+Ex res)/(Exbm+ ∑Exch.+ExLT)


The corn based plants positive energy results are doubtful exergy results.

## Energy a thermo dynamic analysis technique

Exergy is defined as "exergy is the maximum work that can be produced when a heat or material stream is brought to equilibrium in relation to ref environment" ( Dewulf.J,2010) The analysis identifies the energy and exergy loses in a system which is usually used in a poly-generation System and as for mainly thermochemical pathways The biofuel generation is considered as more successful in an integrated plant of first and second generation. The thermodynamic efficiency of a system is

efficiency =(Exergy of useful products )/(Input Energy)


For Lignocellulosic

efficiency = (Exet+Pnet+Ex res)/(Exbm+ ?Exch.+ExLT)


The corn based plants positive energy results are doubtful exergy results.

## Effects of acid treatment on different parts of corn stalk for second generation of ethanol production

Source: Li, Ping."Effects of acid treatment on different parts of corn stalk for second generation of ethanol production" Bioresource Technology (2016).[19]

The effect of acid treatment has different effects on different parts of corn stalk for second generation ethanol production. Sulfuric acid is mostly used to depolymerize the lignin and hemicellulose fractions. pretreatment - 2% (w/v),H2SO4,121°C under 10%(w/v) solid loading for 60 min Solid fractions then collected at 105°C overnight, and stored at 4°C. Enzymatic hydrolysis/fermentation

• 50°C,150rpm in 0.01M citrate buffer (pH 4.7)

Cellulase 15FPU/g of solid Fermentation was performed 30°C/200rpm in 1L bio reactor with working volume of 600ml,pH at 6 by ammonia,Sterilization of hydrolysis was done at 121°C . Recovery rate of Solid = Wpre/Wraw*100 Glucose Yield % = (amount of glucose in enxyme hydrolysate*0.9)/(amount of cellulose in pre treatment sample*100%) The Glucose content in husk was found high, lignin content was low ,xylan content was high in cob. Pro pre-treatment enhanced the overall efficiency in ethanol production. Ethanol Energy Return on Investment A survey of the literature 1990-present (http://pubs.acs.org/doi/abs/10.1021/es052024h) Roel Hammerschlag" Ethanol Energy Return on Investment A survey of the literature 1990-present" The paper discusses the net energy return on ethanol production- a review of different studies has been taken into account. The studies considered two methods, ethanol from corn starch and cellulosic ethanol. The term RE has been considered to represent the net energy of ethanol to the non –renewable energy input in manufacturing process. Studies by pizmental & patzak implied that the net renewable energy return is zero for the invested fossil fuels .

## Pretreatment technologies for efficient bioethanol production process based on enzymatic hydrolysis

Source: Alvira, Petal."Pretreatment technologies for efficient bioethanol production process based on enzymatic hydrolysis" Bioresource technology 101.13 (2010): 4851-4861.[20]

The paper concerns the issues regarding the technologies employed in biofuel produce from
lignocellulosic materials. The process has a lot of chemical barriers as it should lead to high yields, digestible. The amount of toxin compounds should be kept low .The energy consumption can be kept low if the dry content is high in raw material.to ensure adequate ethanol produce concentration of sugar from coupled operation should be kept above 10%.heat requirements should be kept low.


Among all the pre-treatment methods considered chemical and thermochemical found to be the best technologies available.

## Biomass Electricity generation at ethanol plants –achieving maximum impact

Source: Morey, R. V., and D. G. Tiffany. "Biomass Electricity generation at ethanol plants –achieving maximum impact" Final report for XCEL energy renewable development fund project RD3–23 [internet](2011 Dec)[cited 2013 Jan 11].[21]

The paper studies the energy and electrical needs of 50 million gallon/year ethanol plant. The system performance of superheated steam drying and conventional steam tube drying are done for syrup and corn stover, corn stover fuels. It was found that superheated steam drying had more efficiency in electrical generation and low thermal efficiency. The process heat required was also less than the steam tube dryer. System performance was same for both syrup and corn stover, corn-stover.as syrup-corn stover had a small increase in the power sent back to grid. There's reduction in GHG gases due to increase in electricity production. The corn entering into a plant is usually converted into one-third of distilled grains, one-third of CO2.Two driers are used for syrup and corn stover. The net energy required to remove water in superheated system drier is about 1000 KJ/kg(430 btu/lb) compared to about 2070KJ/kg (1150 BTU/lb) The water condensed is reused in ethanol processing thus reducing net water intake in ethanol processing. The logistics and storage of bio raw material has been studied.

## Net energy balance of ethanol production

The paper review about the net energy balance of ethanol produce. The net value of energy is considered positive as the net intake of energy and non-renewable resources has decreased over years Average yield of 2.76 gallons of ethanol/bushel of corn was reported .with approx. 2.74% -wetmill,2.81% -dry mill. BTU per gallon of ethanol produced is around 20545. The large portion of energy consumed is in drying co-product distillers grain. 42 gallons of water per gallon of ethanol is consumed. The corn produced in US is mostly not irrigated co-products from plants are distiller grains for livestock feed and CO2 in food and beverage industry. The paper makes a strong point on considering the net energy credits to by-products obtained

Page data
Type Literature review Saurabh Chaudhari, Namitha Ramachandran, shravan kumar bittla 2016 CC-BY-SA-4.0 202 No main image Saurabh Chaudhari, Namitha Ramachandran, shravan kumar bittla (2016). "Biofuel vs PV literature review". Appropedia. Retrieved August 19, 2022.
1. Schmer, Marty R.."Net energy from cellulose ethanol from switchgrass" Proceedings of the National Academy of Sciences 105.2 (2008): 464-469.
2. Chen, H., and G. Q. Chen."Energy cost of rapeseed based biodiesel as alternative energy in china" Renewable Energy 36.5 (2011): 1374-1378.
3. Prade, Thomas, Sven-Erik Svensson, and Jan Erik Mattsson. "Energy balances for biogas and solid biofuel production from industrial hemp" Biomass and bioenergy 40 (2012): 36-52.
4. Liska, Adam J.."Improvements in Life Cycle Energy Efficiency and Greenhouse Gas Emissions of Corn-Ethanol" Journal of Industrial Ecology 13.1 (2009): 58-74.
5. Shonnard, David R., Larry Williams, and Tom N. Kalnes. "Camelina Derived jet fuel and diesel: Sustainable advanced biofuels" Environmental Progress & Sustainable Energy 29.3 (2010): 382-392.
6. Gasol, Carles M.."A life cycle assessment of biodiesel production from winter rape grown in southern Europe" Biomass and Bioenergy 40 (2012): 71-81.
7. Ptasinski, Krzysztof J., Mark J. Prins, and Anke Pierik. "Exergetic evaluation of biomass gasification" Energy 32.4 (2007): 568-574.
8. Liska, Adam J.."Improvements in life cycle Energy Efficiency and Green House Gas Emissions of Corn Ethanol " Journal of Industrial Ecology 13.1 (2009): 58-74.
9. Liska, Adam J.."Improvements in life cycle Energy Efficiency and Green House Gas Emissions of Corn Ethanol" Journal of Industrial Ecology 13.1 (2009): 58-74.
10. Mumm, Rita H.."Land usage attributed to corn ethanol production in United States: sensitivity to technological advances in corn grain yield, ethanol conversion and co-product utilization" Biotechnology for biofuels 7.1 (2014): 1.
11. Kim, Seungdo, Bruce E. Dale, and Robin Jenkins. "Life Cycle Assessment of Corn Grain and Corn Stover in the United States" The International Journal of Life Cycle Assessment 14.2 (2009): 160-174.
12. Shapouri, Hosein. "2008 Energy Balance for Corn-Ethanol Industry". DIANE Publishing, 2011.
13. Graham, Robin Lambert."Current and potential U.S Corn Stover Supplies" Agronomy Journal 99.1 (2007): 1-11.
14. Pimentel, David, and Tad W. Patzek. "Ethanol Production Using Corn, Switchgrass, and Wood; Biodiesel Production Using Soybean and Sunflower" Natural resources research 14.1 (2005): 65-76.
15. Hosein Shapouri,"The 2001 Net Energy Balance of Corn Ethanol"
16. Gallagher, Paul W., and Harry Baumes. "Biomass Supply From Corn Residues: Estimates and Critical Review of Procedures" USDA, Washington, DC, USA.
17. Agricultural Statistics
18. Kang, Qian, and Tianwei Tan. "Exergy and CO2 Analyses as key tools for the evaluation of Bio-Ethanol Production" Sustainability 8.1 (2016): 76.
19. Li, Ping."Effects of acid treatment on different parts of corn stalk for second generation of ethanol production" Bioresource Technology (2016).
20. Alvira, Petal."Pretreatment technologies for efficient bioethanol production process based on enzymatic hydrolysis" Bioresource technology 101.13 (2010): 4851-4861.
21. Morey, R. V., and D. G. Tiffany. "Biomass Electricity generation at ethanol plants –achieving maximum impact" Final report for XCEL energy renewable development fund project RD3–23 [internet](2011 Dec)[cited 2013 Jan 11].
22. cleanfuelsdc.org" Net energy balance of ethanol production"
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