Biofuels for the Short Term

Summary Statement

• We propose that biofuels will be used as a transition from diesel trucks to electric trucks from 2021 to 2040 because they are easier to implement compared to electricity 
• The specific biofuel technology for the proposed solution is the alcohol gasoline flex fuel engine, with ethanol being the preferred source for alcohol 
• Ethanol is a better source than methanol because most methanol produced comes from gray methanol, which is responsible for emitting greenhouse gases 
• Currently, bioethanol is economically more feasible than electricity because the cost to build stations and converting diesel trucks to bioethanol is cheaper compared to the infrastructure costs for electric trucks 
• Greater reduction of greenhouse gases for biofuels can come from using waste

Introduction

Although electricity and catenary are the best solutions for sustainable trucking (see Why Electric), the high economic cost of electric trucks as well as the current inadequate infrastructure prevents this new technology from being implemented right away. According to the International Council on Clean Transportation (ICCT), converting all heavy-duty trucks to zero-emission vehicles by 2040 would require a total of $238 billion dollars in both public and private investment to cover the costs of batteries, charging stations, etc.^[1]Minjares , Ray, et al. “Infrastructure to Support a 100% Zero-Emission Tractor-Trailer Fleet in the United States by 2040.” The International Council on Clean Transportation, 14 Sept. 2021, … Continue reading One feasible and economical solution that can be carried out for the next decade before electric trucks become economical is the use of biofuels, a type of renewable fuel that uses biomass. Biomass comes from plant-based matter that includes crops, waste, etc.^[2]“Biofuel Basics.” Bioenergy Technologies Office, Office of Energy Efficiency & Renewable Energy, https://www.energy.gov/eere/bioenergy/biofuel-basics. Biodiesel and ethanol fall under the biofuels umbrella and are distinct types of fuel. Biodiesel can come from vegetable oil, animal fat, or recycled grease.^[3]“Biofuel Basics.” Bioenergy Technologies Office, Office of Energy Efficiency & Renewable Energy, https://www.energy.gov/eere/bioenergy/biofuel-basics. On the other hand, ethanol primarily comes from corn as corn made up 94% of all U.S. ethanol production in 2012.^[4]“U.S. Bioenergy Statistics.” USDA ERS – U.S. Bioenergy Statistics, Economic Research Service – U.S. Department of Agriculture , 2021,  … Continue reading A specific biofuels technology that can reduce greenhouse gas emissions while being an economically feasible solution is the alcohol gasoline flex fuel engine.

Alcohol Gasoline Flex Fuel Engine

The alcohol gasoline flex fuel engine uses a hybrid of ethanol and gasoline with a spark ignition engine. Compared to the diesel engine, the spark ignition engine decreases the amount of nitrous oxide (NO_x) emissions by 90%.^[5]Stauffer, Nancy W. “Getting the World off Dirty Diesels.” MIT Energy Initiative, 6 July 2018, https://www.energy.mit.edu/news/getting-the-world-off-dirty-diesels. A diesel engine makes more NO_x because the engine uses compression ignition and does not use a stoichiometric ratio. The stoichiometric ratio is when the amount of air required for complete combustion is met.^[6]“3 Questions: Daniel Cohn on the Benefits of High-Efficiency, Flexible Fuel Engines for Heavy-Duty Trucking.” MIT Energy Initiative, 15 September 2021,  … Continue reading It is important to reduce NO_x emissions because they are responsible for causing premature deaths and respiratory health problems. Not only that, but also they contribute to air pollution.^[7]“3 Questions: Daniel Cohn on the Benefits of High-Efficiency, Flexible Fuel Engines for Heavy-Duty Trucking.” MIT Energy Initiative, 15 September 2021, … Continue reading Although 90% may sound high, this figure is achievable because the trucking company Cummins made the L9N engine that satisfies this level of reduction of NO_x emissions. Another benefit of the alcohol gasoline flex engine is that it significantly reduces carbon dioxide emissions by 20% to 40%.^[8]“3 Questions: Daniel Cohn on the Benefits of High-Efficiency, Flexible Fuel Engines for Heavy-Duty Trucking.” MIT Energy Initiative, 15 September 2021, … Continue reading The technology behind the spark ignition engine is a three way catalyst and there is a stoichiometric ratio.^[9]Cohn, D. and Bromberg, L., “Flex Fuel Gasoline-Alcohol Engine for Near Zero Emissions Plug-In Hybrid Long-Haul Trucks,” SAE Technical Paper 2019-01-0565, 2019, … Continue reading The three way catalyst is a heterogeneous catalyst that converts toxic gases like NO_x into harmless ones by using a palladium or platinum surface.^[10]Berger, Alan, et al. “Three Way Catalytic Converter.” TWC – Three Way Catalytic Converter, 2009, http://www.cchem.berkeley.edu/molsim/teaching/fall2009/catalytic_converter/bkgcatcon.html. The purpose of developing an engine that can be powered by both ethanol and gasoline is to provide flexibility in case the truck is not near any ethanol station and can only use gasoline. For now, the blend for using the alcohol gasoline engine is E10 (10% ethanol), though a high alcohol concentration such as E85 can be achieved if an additional fuel injection system is used.^[11]Berger, Alan, et al. “Three Way Catalytic Converter.” TWC – Three Way Catalytic Converter, 2009, http://www.cchem.berkeley.edu/molsim/teaching/fall2009/catalytic_converter/bkgcatcon.html.

Limitations 

Currently, biofuels come mainly from growing feedstock crops that include corn, soybean, and sugarcane. As stated before, biofuels are a type of renewable energy that uses biomass and biomass comes from plant-based matter. Demands of biofuels have increased by four times from 2005 to 2016 (35 billion liters to 135 billion liters). In order to meet these growing demands, agricultural industries need to use more resources such as water, land, and fertilizers.^[12]Liu, B., Rajagopal, D. Life-cycle energy and climate benefits of energy recovery from wastes and biomass residues in the United States. Nat Energy 4, 700–708 (2019). … Continue reading Compared to the 2005 irrigation water use and cropland use for biofuels, the estimated numbers for 2030 are significantly greater in the U.S. and Canada (Fig. 1) as the study predicts the percentage of water for irrigation use to increase by 8 times and the percentage of water for cropland use to double. These resources are limited and in the long run, can lead to negative consequences on the environment including habitat destruction and deforestation.^[13]“Biofuels Explained: Biomass-Based Diesel and the Environment.” Biodiesel and the Environment , U.S. Energy Information Administration, 10 Dec. 2020, … Continue reading

Another disadvantage is that some places in the world burn forests to convert the land into soybean and palm oil plantations. Besides having negative effects on the environment, the increased reliance on biofuels can lead to economic downsides by increasing food prices by 20-50%.^[14]Liu, B., Rajagopal, D. Life-cycle energy and climate benefits of energy recovery from wastes and biomass residues in the United States. Nat Energy 4, 700–708 (2019). … Continue reading

Source of Ethanol 

Ethanol comes from fermenting feedstocks that are composed of sugars from carbohydrates. The most common source for ethanol is corn, though other feedstocks like sugarcane can also work. For cellulose materials, there is a biochemical process involving hydrolysis that breaks down cellulose, a polysaccharide, into sugars. Then, the sugar gets fermented to make ethanol. The majority of ethanol plants use dry mills that break down the corn into flour and then use fermentation to produce ethanol.^[16]“Ethanol Fuel Basics.” Alternative Fuels Data Center: Ethanol Fuel Basics, U.S. Department of Energy, https://www.afdc.energy.gov/fuels/ethanol_fuel_basics.html.

In the U.S., the three common blends are E10, E15, and E85. E10 means that the maximum concentration in the biofuel is 10% ethanol. Similarly, E85 is not exactly 85% ethanol as it can range from 51% to 83% ethanol. Currently, there are around 4100 ethanol (E85) stations in the U.S. that are evenly scattered throughout the country, though there is a higher density in the Midwest, with very few in the Pacific Northwest.^[17]“Ethanol Fueling Station Locations.” Alternative Fuels Data Center: Ethanol Fueling Station Locations, U.S. Department of Energy, … Continue reading 

Why Ethanol?

Biodiesel is another type of biofuel, but the main issue with biodiesel is that there aren’t enough biodiesel stations. The current number of stations in the U.S. with B20 or higher (B20 is 20% biodiesel) is 334.^[18]“Ethanol Fueling Station Locations.” Alternative Fuels Data Center: Ethanol Fueling Station Locations, U.S. Department of Energy, … Continue reading This is a lot fewer compared to the current number of stations in the U.S. with E85 (4100). Therefore, using biodiesel instead of ethanol would require a higher infrastructure cost to build significantly more stations to meet the national demand. Based on numbers from 2019, 2.6 billion gallons of biodiesel were made in a year, a far cry from 17.3 billion gallons of ethanol made in a year.^[19]“U.S. Energy Information Administration – EIA – Independent Statistics and Analysis.” EIA Releases Plant-Level U.S. Biodiesel Production Capacity Data, U.S. Energy Information … Continue reading^[20]“U.S. Energy Information Administration – EIA – Independent Statistics and Analysis.” U.S. Fuel Ethanol Production Capacity Increased by 3% in 2019, U.S. Energy Information … Continue reading 

Another important thing to note is that corn for ethanol has a greater yield (401 gallons per acre) compared to soybean oil for biodiesel (59 gallons per acre), the primary source of biodiesel in the U.S.^[21]“Biofuels Factsheet.” Biofuels Factsheet | Center for Sustainable Systems, Regents of the University of Michigan, 2021, https://www.css.umich.edu/factsheets/biofuels-factsheet.When it comes to the environmental effects, corn ethanol can decrease greenhouse emissions by 34% (taking land use into account), whereas biodiesel reduces emissions by 15%.^[22]“Biofuels Factsheet.” Biofuels Factsheet | Center for Sustainable Systems, Regents of the University of Michigan, 2021, https://www.css.umich.edu/factsheets/biofuels-factsheet. In addition, there are more ethanol refineries (201) than biodiesel plants (91) as of 2020.^[23]“Biofuels Factsheet.” Biofuels Factsheet | Center for Sustainable Systems, Regents of the University of Michigan, 2021, https://www.css.umich.edu/factsheets/biofuels-factsheet. According to the U.S. Energy Information Administration, the production of all biodiesel was 1.82 billion gallons in 2020, whereas the production of all ethanol was 13.93 billion gallons in 2020.^[24]“U.S. Energy Information Administration – EIA – Independent Statistics and Analysis.” Monthly Biodiesel Production Report, 26 Feb. 2021, U.S. Energy Information Administration, … Continue reading These numbers show that on average, each ethanol plant can produce a higher volume compared to each biodiesel plant. 

Although methanol can be used in place of ethanol and is more energy efficient because of its higher flame speed, the greenhouse emissions generated to produce methanol may be greater than ethanol depending on how the methanol is made. There are three types of methanol: grey, blue, and green (see methanol under ships). Green methanol can either be bioethanol or e-methanol.^[26]Martin, Abigail. “A Step Forward for ‘Green’ Methanol and Its Potential to Deliver Deep GHG Reductions in Maritime Shipping .” The International Council on Clean Transportation, 1 Sept. … Continue reading The majority of methanol produced comes from natural gas (grey or blue) that relies on a coal or steam refinery process. Using natural gas isn’t a clean source of energy because natural gas comes from fossil fuels, a nonrenewable type of energy. On the other hand, ethanol is made from crops and biomass that include corn, cellulose, etc. While blue methanol (~80 g CO₂ of equivalent/MegaJoules) releases fewer well-to-wake (WTWa) greenhouse gas emissions compared to grey methanol (>90 g CO₂e/MJ), it is still a high value.^[27]Martin, Abigail. “A Step Forward for ‘Green’ Methanol and Its Potential to Deliver Deep GHG Reductions in Maritime Shipping .” The International Council on Clean Transportation, 1 Sept. … Continue reading Well-to-wake (WTWa) greenhouse gas emissions takes the total of upstream (well-to-tank) and downstream (tank-to-wake) emissions, with upstream involving the production process and downstream being the emissions released from using the fuel.^[28]“T Is for Tank-to-Wheel (TTW).” Volkswagen Group Homepage, Volkswagen AG 2021, https://www.volkswagenag.com/en/group/the-a-to-z-of-e-mobility/t-is-for-tank-to-wheel.html. Taking land use change into account, corn ethanol’s greenhouse gas emissions is 53 g CO₂e/MJ, which is lower than grey and blue methanol’s value.^[29]Wang, Michael, et al. “Life -Cycle Greenhouse Gas Emission Reductions of Ethanol with the GREET Model.” Argonne National Laboratory, U.S. Department of Energy, 17 Feb. 2021, … Continue reading While methanol may not be the ideal fuel source for trucks, it may be an appropriate choice for ships because the energy demands of a transoceanic vessel vary greatly from those of a truck (click here for more information on methanol as a marine fuel). 

Costs of Implementation

Unlike biofuels, trucks running on electricity require additional costs that include building charging point stations to charge heavy-duty vehicles. Even though there are currently more than 45,500 electric charging stations in the United States, these stations are for cars and cannot be used for electric trucks.^[32]“Electric Vehicle Charging Station Locations.” Alternative Fuels Data Center: Electric Vehicle Charging Station Locations, U.S. Department of Energy, … Continue reading Based on the fact that trucks have a significantly larger size and are estimated to have a larger battery, they will require charging stations with a higher power that range from 350 kW to 1 MW. The estimated cost for building 31700 public chargers amounts to $6.4 billion by 2030.^[33]Minjares, Ray, et al. “Infrastructure to Support a 100% Zero-Emission Tractor-Trailer Fleet in the United States by 2040.” The International Council on Clean Transportation, 14 Sept. 2021, … Continue readingTherefore, the cost of each public charger is around $200,000 ($6.4 billion divided by 31700 chargers = $200,000 per charger), though the actual figure is slightly lower because the paper also included 220 hydrogen fueling stations into the total cost. On the other hand, the average cost for installing a new ethanol E85 pump is estimated to be $71,735, which is significantly lower than $200,000.^[34]“Cost of Adding E85 Fueling Capability to Existing Gasoline Stations: NREL Survey and Literature Search.” National Renewable Energy Laboratory, Mar. 2008, … Continue reading An important thing to note is that the range of costs for installing an ethanol E85 pump has a wide range of costs from $7,559 to $247,600 and the data is from 2008, so it is relatively outdated and the current cost for an E85 pump in 2021 is most likely to be cheaper.^[35]“Cost of Adding E85 Fueling Capability to Existing Gasoline Stations: NREL Survey and Literature Search.” National Renewable Energy Laboratory, Mar. 2008, … Continue reading 

When it comes to the cost of converting a truck on a diesel engine that uses E15 (the typical blend) to a flex fuel engine that uses E85, the numbers are yet to be determined as current research does not provide numbers specifically for trucks. The conversion of a diesel truck to a bioethanol truck would only require buying a new fuel sensor, electronic control module, and a spark ignition engine if the truck is 20 years or younger.^[37]“Cost of Adding E85 Fueling Capability to Existing Gasoline Stations: NREL Survey and Literature Search.” National Renewable Energy Laboratory, Mar. 2008, … Continue reading On the other hand, converting a diesel truck to an electric truck would require buying a new electric truck to replace the old truck because electric trucks run on batteries. From these observations, it is safe to assume that converting a diesel truck to a bioethanol truck would cost less money than converting a diesel truck to an electric truck.

Future Considerations

A solution that addresses the present-day problems in biofuels is using various forms of waste as a fuel source instead of growing edible crops. A lot of waste from agriculture, forestry, and landfills goes unused when they can be used for renewable energy. Compared to the conventional way of producing biofuels from mass agriculture, using waste is more sustainable because this method does not require using energy to grow crops. On the other hand, corn ethanol requires growing 150 megatons of corn in order to meet the U.S. demand of 60 billion liters of corn ethanol.^[38]Bell, Allison. “Converting Waste, ‘a Leftover Resource,’ to Biofuels Reduces Emissions.” Institute of the Environment and Sustainability at UCLA, The Regents of the University of … Continue reading If successfully implemented, the U.S. can make 3.1 to 3.8 exajoules (EJ) of renewable energy from using the given waste resources, ultimately reducing 103 to 178 million metric tons of carbon dioxide emissions.^[39]Bell, Allison. “Converting Waste, ‘a Leftover Resource,’ to Biofuels Reduces Emissions.” Institute of the Environment and Sustainability at UCLA, The Regents of the University of … Continue reading There are 1.0*10¹⁸ Joules in 1 exajoule. In order to achieve this number of maximal energy production, this means obtaining energy from a wide range of waste and biomass sources, such as cow manure. This figure equates to removing 37 million passenger cars, assuming that the average car emits 4.6 metric tons of carbon dioxide each year.^[40]Bell, Allison. “Converting Waste, ‘a Leftover Resource,’ to Biofuels Reduces Emissions.” Institute of the Environment and Sustainability at UCLA, The Regents of the University of … Continue reading

Case Study: Scania Truck 

One company that has successfully built a truck for long-distance journeys that runs on ethanol is Scania’s 410 hp (horsepower) truck that uses a 13-liter engine. The horsepower is lower than the standard Cummins engines for class 7 and class 8 trucks that range from 350 to 605 hp. The engine is 2150 Newton-meters (a unit for torque), which is the same as the diesel engine. The fuel used is ED95 which is 95% ethanol and 5% ignition improver and is made by a Swedish company called SEKAB.^[41]“Scania’s Bioethanol Engine Reduces CO2 Emissions.” Scania Group, 19 Feb. 2020, https://www.scania.com/group/en/home/newsroom/news/2018/scanias-bioethanol-engine-reduces-CO2-emissions.html. Not only does the truck reduce carbon dioxide emissions up to 90%, but the truck also significantly decreases the amount of particulate matter and nitrogen oxide emissions. The company’s press article does not provide information about the range of the truck and fuel economy.