Converting Sweets to Biofuels

By Craig Cammarata

It is no secret that the United States has a collective sweet tooth. According to the Center for Science in the Public Interest, “America is drowning in sugar.” We all enjoy occasional, or not so occasional, sweets, but there are opportunity costs associated with our consumption of caloric sweeteners. It is quite possible to use the caloric sweeteners manufactured from sugarcane, sugar beet, and corn for bioethanol production. The purpose of this paper is to evaluate the potential of this reallocation by estimating the amount of gasoline that could be offset by converting our use of caloric sweeteners to bioethanol.

INTRODUCTION

It is no secret that the United States has a collective sweet tooth. According to the Center for Science in the Public Interest, “America is drowning in sugar.” In fact, U.S. sugar consumption has increased by 28 percent since 1983 and this increasing habit is considered to be a major reason for increasing obesity rates and other health problems [1]. Furthermore, sugar consumption, according to surveys from the United States Department of Agriculture (USDA), has increased almost every year since 1982. The typical person with a healthy 2,000-calorie diet should be consuming a maximum of 10 teaspoons of added sugars per day, but the average American consumes twice that amount [1].

We all enjoy occasional, or not so occasional, sweets, but there are opportunity costs associated with our consumption of caloric sweeteners. In addition to the health problems that are correlated with the overconsumption of these sweeteners, Americans are foregoing the opportunity to use the embodied energy in those products for transportation fuels. It is quite possible to use the sugar products manufactured from sugarcane, sugar beet, and corn for bioethanol production. Reallocating the use of those sugar products could create a win-win scenario by mitigating the health issues related to the overconsumption of caloric sweeteners in food products and generating additional bioethanol for transportation fuel. The purpose of this paper is to evaluate the potential of this reallocation by estimating the amount of gasoline that could be offset by converting our use of caloric sweeteners to bioethanol.

PRODUCTION AND CONSUMPTION OF SWEETENERS

Caloric sweeteners come from three major feedstocks. The first feedstock is corn silage, which can be converted to corn sweeteners such as high fructose corn syrup (HFCS), glucose syrup and dextrose [5]. Corn silage is “the entire above-ground portion of the corn plant (including the ear) that is harvested by cutting and chopping the plant before it reaches maturity” [3]. The other two feedstocks are sugarcane and sugar beet, which are typically converted to raw sugar [5]. Table 1 shows the U.S. production of caloric sweeteners from all three feedstocks over the last three fiscal years. Corn feedstocks recently comprise more than 60 percent of total caloric sweetener production, with HFCS comprising about 70 percent of corn sweetener production.

table-1
The average American consumes 20 teaspoons of caloric sweeteners per day, which equates to almost 30 kg per year [1]. Table 2 shows the current U.S. consumption of centrifugal sugar, along with its production and import and export flows. Centrifugal sugar is an industrial term for the end product of modern sugar factories and is not the raw form of the product. The raw form of caloric sweeteners are the products from which bioethanol is derived from [5]. Theoretically, trade inflows and outflows of those products are potential sources of bioethanol. Whereas it may be inefficient to import raw sugar products to produce bioethanol, reallocating the feedstocks of nationally produced caloric sweeteners could serve as legitimate sources of fuel.

table-2
CONVERSION POTENTIAL

Critics of bioethanol typically claim that the fuel source uses too much upstream energy, meaning that the conversion efficiency is low and energy intensive, and that the energy potential per hectare is too low. However, Brazil, the world leader in bioethanol production and use, has achieved great economies of scale with bioethanol produced from sugarcane. In Brazil, bioethanol converted from sugarcane has a very high energy balance, which is on the order of “8.3 units of energy delivered per each unit of fossil fuel spent for its production” [7]. Additionally, sugar beet harvests in Germany have an energy yield of 7.9 MJ delivered per MJ of fossil fuel consumption [9]. Both examples show promise in meeting a legitimate energy conversion rate for bioethanol.

Brazil has generated improvements in energy yield per hectare as well. In the 1970s, Brazil produced an annual bioethanol yield of a little less than 800 gallons per 1.5 million hectares. Now, Brazil produces an annual average of 1,850 gallons per hectare [7]. Whereas Brazil’s sugar yield is incomparably high due to its favorable climate, sugar beet can offer a similar yield at 1,750 gallons per hectare at climate zones with shorter growing seasons, such as the temperate zones in the U.S [4,9]. In fact, sugar beet can consistently yield more bioethanol than sugarcane in temperate climates. With recent sugar beet yields of 58.5 mt per hectare, U.S. farmers can produce an average of 1,700 gallons of bioethanol per hectare [4].

OFFSETTING OF GASOLINE WITH ETHANOL FROM SWEETS

In evaluating the potential reduction of gasoline through bioethanol produced from caloric sweetener feedstocks, this analysis was dependent upon two types of conversion rates. The first type was the rate at which a feedstock could be converted to a caloric sweetener. The USDA reports the production, consumption, import and export of caloric sweeteners in short tons (dry weight) of finished product. Bioethanol is derived from a different process than that which produces caloric sweeteners. Therefore, the total amount of feedstock (i.e. corn silage, sugarcane and sugar beet) that produced those sweeteners must be known in order to calculate the potential volume of biofuel that could be produced from a reallocation of those resources. Those conversion rates, displayed in Table 3, were used to determine the total amount of corn silage, sugarcane and sugar beet available for bioethanol production.

table-31
Calculating the rates for converting each feedstock to bioethanol was the second key component of this analysis. Multiplying each feedstock’s production by it respective bioethanol conversion rate yielded the total amount of bioethanol that could be produced if all the feedstocks for caloric sweeteners were used for bioethanol production. Those conversion rates are in Table 3 and were calculated using conversion figures collected by the U.K. Department for Transportation (UKDfT), Kaltner et al., and Icoz et al. [7,9,10]. Table 4 shows the total feedstock inputs for caloric sweeteners from corn, sugarcane and sugar beet over the last three fiscal years.

table-4
Despite the efficiency advances for converting bioethanol from sugarcane and sugar beet, the U.S. is a nation supplied by corn-based products. As Table 1 in the previous section shows, caloric sweeteners from corn comprise about 60 percent of the sugar additives consumed by Americans. This phenomenon is not surprising, considering that corn is the main agricultural product in the U.S. At a conversion rate of about 40 bushels of processed corn per metric ton of corn silage, with a bushel typically equaling 56 pounds, the U.S. used a little over 100 million mt of corn silage to meet its FY2008 corn sweetener production (Table 4) [2,6].

In addition to the U.S. production of corn sweeteners, the demand for caloric sweeteners in the U.S. is met through the combination of raw sugar produced by nationally grown sugar beet and sugarcane, and supplemented by the importation of raw or refined sugar from other countries; mainly Brazil, the Dominican Republic, the Philippines and Mexico [5]. A practical application of this study would be to only convert all caloric sweetener feedstocks that were produced in the U.S. to gallons of biofuels. This is because it would be inefficient, and more costly, to import raw sugar for the purpose of converting it into bioethanol. Instead, purchasing the ethanol from Brazil, who is more efficient in converting sugarcane to bioethanol, would be a more realistic scenario. Regardless, the purpose of this analysis was to calculate the total amount of bioethanol Americans forego by consuming caloric sweeteners. Using Energy Information Agency (EIA) data on U.S. gasoline consumption and the conversion rates in Table 3, Table 5 calculates the total number of gallons of gasoline, by feedstock, that would have been offset if the U.S. did not consume caloric sweeteners over the last three fiscal years [11,12].

table-51
When interpreting Table 5, there are two important things to note. First, feedstocks from imported raw sugar, although not grown in the U.S., are included in the table. Including those imports in the overall calculation better quantifies the foregone opportunity of producing bioethanol, even though this is unrealistic for the reasons previously mentioned. Second, one gallon of bioethanol is equivalent to about 0.65 gallons of gasoline [10]. This loss in efficiency is due to the considerably lower heating value of bioethanol [9]. Thus, bioethanol produced from corn silage, sugarcane or sugar beet offers considerably less energy per gallon.

DISCUSSION

At first glance, Table 5 suggests that Americans should not feel too guilty about eating sweets; at least not from an energy perspective. Even with the close to record highs in U.S. sugar and corn sweetener production in FY 2007, the potential bioethanol that could have been produced from the feedstocks of that production, along with the imported sugar, would have reduced U.S. gasoline consumption by only 1.66 percent [5].

Although eliminating caloric sweeteners from the American diet would produce a dismally low amount of bioethanol, the collective conscience of the U.S. population should not be relieved of any guilt from the forgone opportunity to produce additional bioethanol. Assuming that bioethanol is carbon neutral, and this is a big assumption, each teaspoon of caloric sweetener that is not converted to bioethanol contributes to additional carbon dioxide emissions from gasoline use that could have been prevented. With an average of 8.81 kg of CO2 emitted per gallon of gasoline burned, that measly 1.66 percent equates to a missed opportunity to mitigate 19.1 million mt of CO2 [8]. So, are you feeling guilty now?

Works Cited

[1] “”America: Drowning in Sugar”” Center for Science in the Public Interest. 16 Apr. 2009 <http://www.cspinet.org/new/sugar.html>.

[2] “Bioenergy Conversion Factors.” Bioenergy Feedstock Information Network (BFIN) Administration Site. U.S. Department of Energy, Oak Ridge National Laboratory. 16 Apr. 2009 <http://bioenergy.ornl.gov/papers/misc/energy_conv.html>.

[3] “Corn Field Math.” Oklahoma State University. 16 Apr. 2009 <http://www.clover.okstate.edu/fourh/aitc/lessons/upper/cornmath.pdf>.

[4] “ERS/USDA Briefing Room – Sugar and Sweeteners: Background.” U.S. Department of Agriculture, Economic Research Service. 16 Apr. 2009 <http://www.ers.usda.gov/Briefing/Sugar/Background.htm>.

[5] “ERS/USDA Briefing Room – Sugar and Sweeteners: Recommended Data.” U.S. Department of Agriculture, Economic Research Service. 16 Apr. 2009 <http://www.ers.usda.gov/Briefing/Sugar/data.htm>.

[6] “ERS/USDA Data – Feed Grains Database: Documentation.” U.S. Department of Agriculture, Economic Research Service. 16 Apr. 2009 <http://www.ers.usda.gov/Data/FeedGrains/Documentation.aspx>.

[7] Germany. Federal Ministry of Food, Agriculture and Consumer Protection. Liquid Biofuels for Transportation in Brazil: Potential and Implications for Sustainable Agriculture and Energy in the 21st Century. By Franz J. Kaltner, Gil Floro P. Azevedo, Ivonice A. Campos, and Agenor O. Mundim. 2nd ed. German Technical Cooperation, 2005. 28 Nov. 2005. 16 Apr. 2009 <http://www.fbds.org.br/IMG/pdf/doc-116.pdf>.

[8] “Green Power Equivalency Calculator Methodologies | Green Power Partnership | US EPA.” U.S. Environmental Protection Agency. 16 Apr. 2009 <http://www.epa.gov/greenpower/pubs/calcmeth.htm>.

[9] Icoz, Erkan, K. Mehmet Tugrul, Ahmet Saral, and Ebru Icoz. “Research on ethanol production and use from sugar beet in Turkey.” Biomass and Bioenergy 33 (2009): 1-7.

[10] “International resource costs of biodiesel and bioethanol.” United Kingdom Department for Transport. 16 Apr. 2009 <http://www.dft.gov.uk/pgr/roads/environment/research/cqvcf/internationalresourcecostsof3833>.

[11] “Table Definitions, Sources, and Explanatory Notes.” U.S. Department of Energy, Energy Information Agency. 16 Apr. 2009 <http://tonto.eia.doe.gov/dnav/pet/TblDefs/pet_cons_psup_tbldef2.asp>.

[12] “U.S. Product Supplied for Crude Oil and Petroleum Products.” U.S. Department of
Energy, Energy Information Agency. 16 Apr. 2009 <http://tonto.eia.doe.gov/dnav/pet/pet_cons_psup_dc_nus_mbbl_a.htm>.

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2 Responses so far »

  1. 1

    Ola Abass said,

    it’s really great to see thia as this if well developed will help tackle the problem of green house effect I am a final year student of a college in nigera working on a project of usng sugar as a bio fuel It’s great to see this, i would like to know how (in details) the conversion is being done. from sugar to bio ethanol and then to fuel

  2. 2

    Ola Abass said,

    it’s really great to see this happen knowing fully well that if this is well developed,it will help tackle the problem of green house effect.

    I am a final year student of a college in Lagos Nigeria working on a project of using sugar as a bio fuel. I would be glad if you could help with detailed information on how the conversion is being done. from sugar to ethanol and then to fuel.


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