Carbon emissions from biodiesel engines in Brazil compared to other fuels

Coronado et al. (2009) examined the greenhouse gas (GHG) emissions from engines running on biodiesel, from both soybean and frying oil, as compared to the GHG emissions from gasoline, diesel, and anhydrous ethanol engines in Brazil.  The latter three are currently the predominantly used fuels in the Brazilian transportation market.  Pure biodiesel and mixtures of biodiesel and conventional diesel were considered.— Jenny Ward 
Coronado, Christian Rodriguez, Andrade de Carvalho, João, Silveira, José Luz. 2009. Biodiesel CO2 emissions: A comparison with the main fuels in the Brazilian market. Fuel Processing Technology. 90, 204–211

 The authors used data from the Brazilian Association of Automotive Vehicle Manufacturers (ANFAVEA) and the Brazilian Department of Transit (DENATRAN) to develop an idea of the transportation system in the nation.  Then, the CO2 emissions for each fuel were reported in tons of CO2 per m3 of fuel.  The emissions for various blends of biodiesel, and biodiesel from various sources were also compared.  Using the vehicle data from the last five years, the tons of CO2 per year for Brazil were calculated.  Finally, Coronado et al. projected the GHG emissions for pure diesel, 20% biodiesel (B20), and 100% biodiesel (B100) vehicles in Brazil for the next fifteen years.
Ethanol fuel emitted the least amount of carbon (1.511 ton CO2 per m3 fuel), followed by gasoline (2.316 ton CO2 per m3 fuel), soybean-derived biodiesel (2.480 ton CO2 per m3 fuel), and frying oil-derived biodiesel (2.492 ton CO2 per m3 fuel), and diesel fuel was the worst contributor of GHG (2.683 ton CO2 per m3 fuel).  Although by just considering vehicle emissions biofuels seem to have higher carbon footprints, the authors explain that biomass-derived fuels reduce the net atmospheric carbon content because, unlike fossil fuels, they rapidly recycle carbon from the atmosphere into fuel.  The photosynthetic biomass takes CO2 from the atmosphere, then the combustion of biofuels emits CO2 back into the air.  The rapid turnaround is much more carbon efficient than burning fossil fuels, which releases carbon that took millions of years to sequester from the atmosphere.
Coronado and colleagues also display how as the percentage of biofuels in diesel/biodiesel blends increases, the CO2 emissions caused by using these fuels decreases.  They predict that by phasing out diesel and other main fuels, and phasing in biodiesel use in Brazil’s vehicular fleet, the nation will improve its environmental and economic state.

Sustainability of biodiesel production using palm oil versus jatropha oil for feedstock

Palm oil and oil from Jatrohpa curcas L. can be mass produced in Malaysia and used for biofuels production.  Lam et al. (2009) used the life cycle assessment (LCA) process to compare the sustainability of this process using each oil for feedstock.  During the LCA, they considered the plantation and cultivation of each crop, the milling, or extraction, of each oil, and the conversion of each oil into biodiesel.  The sustainability measures were based on land area required, net energy consumption, greenhouse gas (GHG) emissions, and CO2 sequestration.  The debate over whether jatropha oil (a non-food crop) should be used instead of palm oil (a food crop) to prevent food prices from rising was also considered.  After the LCA for each case was conducted, the authors found that palm oil required less land, produced a higher output to input energy ratio, and enabled larger amounts of CO2 to be sequestrated.  Thus palm oil is a much more environmentally efficient feedstock for biodiesel production compared to jatropha oil (Lam et al. 2009).— Jenny Ward 
Lam, Man K., Lee, Keat T., Mohamed, Abdul R. 2009. Life Cycle Assessmet for the Production of Biodiesel: A Case Study in Malaysia for Palm Oil versus Jatropha Oil. Biofuels, Bioproducts, and Biorefining. 3, 601–612

 The authors collected data from recent literature reviews and statistics including from the Malaysian Palm Oil Board (MPOB), the Indonesian Palm Oil Board (IPOB), and various previous studies.  For the plantation stage of the LCA, they analyzed yields of oil per tonne of fresh fruit bunch harvested, fertilizer components, energy and water requirements, peatland use, and CO2 emissions.  For the milling stage, the authors compared oil yields from extraction, energy and water requirements, and CO2 and other GHG emissions.  For the conversion of oil to biodiesel, they compared methanol to oil ratios, percentage yields of biodiesel and glycerol, electricity and steam usage, and CO2 emissions from production and transportation of biodiesel.
The Malaysian government is interested in using jatropha oil to supplement palm oil as a feedstock for biofuels production because jatropha is drought-resistant, able to grow on wasteland, and is not cultivated for food use, thus it would settle the “food versus fuel debate.”  Despite the advantages it may seem to have, Lam et al. found that jatropha oil is less efficient than palm oil when cultivated as feedstock for biodiesel production.  Using palm oil as feedstock for the production of 1 tonne of biodiesel would require 0.28 ha of land per year, while using jatropha oil as feedstock would require 0.61 ha per year, a 118% increase.  Agroforestry techniques and livestock crop integrations cannot be applied to jatropha plantation like they can to palm oil plantation, making jatropha less sustainable.  Production of 1 tonne of palm oil biodiesel has an output to input energy ratio of 2.27, while jatropha oil biodiesel has an energy ratio of 1.92.  These data indicate that 1 tonne of palm oil biofuel would provide 43% more energy than 1 tonne of jatropha oil biofuel.  Finally, after comparing emissions from fertilizers, energy usage, land usage, and logistics, both palm oil biodiesel production and jatropha oil biodiesel production processes were found to emit about 11,000 kg CO2eq/tonne biodiesel each.  When using palm oil however, the amount of CO2 sequestrated was almost 20 times more than when using jatropha oil.  Overall, palm oil was significantly more sustainable than jatropha oil as a feedstock source for biodiesel production in Malaysia.  To determine the true sustainability of biodiesel, the life cycle analysis of the feedstock-to-fuel process must be considered in addition to the immediate social and environmental effects of biofuels production.

Comparison between biofuels and hydrogen as alternative energy sources

The European Union (EU) considers both biofuels and hydrogen as viable sources of energy to replace fossil fuels.  Sobrino et al. (2010) examined, from an economic perspective, the advantages and disadvantages of replacing fossil fuels with biofuels or hydrogen in European vehicles.  Although each alternative source of energy has different reasons for being a plausible fuel replacement, the authors found more reasons for hydrogen to be the more environmentally friendly and economically sound choice. — Jenny Ward 
Fernando Herna ́ndez Sobrino, Carlos Rodrı ́guez Monroy, Jose ́ Luı ́s Herna ́ndez Pe ́rez. 2010. Critical analysis on hydrogen as an alternative to fossil fuels and biofuels for vehicles in Europe. Renewable and Sustainably Energy Reviews 14, 772–780

 The authors first discussed the different reasons for promoting the use of biofuels and hydrogen, which include: reducing the EU’s reliance on foreign oil, constraining the price growth of petroleum, cutting down greenhouse gas emissions, and generating income for the agricultural sector.  Current EU policies in place to mandate the use of alternative fuels were also identified.  Finally, the benefits and difficulties of using hydrogen to power vehicles was analyzed, and compared to biofuels and fossil fuels.
Sobriono et al. found that the best way to compare the efficiency of alternative fuels to gasoline and gasoil was to study the price per unit of energy on the lower heating value (LHV) of each source. This figure indicated that hydrogen was a more efficicient source of alternative fuel, compared to biofuels and gasoline.  And although biofuels may boost the agriculture industry and decrease CO2 emissions form cars, their production still requires raw materials to be imported from non-EU nations, consumes energy and releases greenhouse gases, and is not cost effective yet.
Hydrogen, produced by electrolysis of sea water, can be used in internal combustion engines or in fuel cells.  This process does require an input of energy, and the authors discovered a wide range of efficiency when using hydrogen as an alternative source of energy.  Its use is most cost effective and least environmentally harmful when wind generators and hydraulic or nuclear power plants provide the energy needed for electrolysis. 
Finally, the authors identify the policies in the EU such as Directive 2003/30/EC, which calls for %5.75 percent of fuels used for transportation to be biofuels by the end of 2010 (Sobrino et al. 2010).  Some of these policies may seem too ambitious because the production of biofuels and hydrogen fuel is much more expensive than current methods for obtaining fossil fuels.  Gas prices however, are heavily taxed, and these taxes could be removed from alternative sources of energy, making them not only a better environmental choice, but also a more affordable option.  

A Sustainable approach to biomass feedstock production for biofuels in Nebraska.

Biomass growth for biofuel use can be an economic and environmentally sustainable production if land and water resources are used efficiently.  The available marginal land and degraded water sources in Nebraska can be used to improve the productivity of biomass growth (Gopalakrishnan et al., 2009).  Utilizing marginal land prevents land for food production from being converted to biofuel growth, making biofuel production more economically and socially feasible.  Incorporating degraded water resources into the irrigation of biomass feedstock will improve the productivity of biofuel growth and contribute to the decontamination of the Nebraska watershed.  After a spatial analysis of Nebraska’s landscape, Gopalakrishnan et al. concluded that an approach to biomass feedstock growth that considers the energy, agricultural, and environmental sectors as part of an overall system is the way to achieve sustainable biofuel production. Jenny Ward
Gopalakrishnan, Gayathri et al. 2009. Biofuels, Land, and Water: A Systems Approach to Sustainability. Environmental Science and Technology 43 (15), 6094–6100

Gayathri Gopalakrishnan and his colleagues used geographic information software to develop and map displaying the marginal land and degraded water sources in Nebraska.  Road and river networks and the locations of two sample biorefineries (one where marginal land is a significant resource and one where it is not) were included in the map.  Four types of marginal land were observed in this study: 1) agricultural land that has been abandoned or set aside for conservation purpose; 2) buffer strips along roads; 3) buffer strips along rivers or riparian buffers; and 4) brownfield sites.  The degraded water resources studied were groundwater sources contaminated by nitrate and wastewater from livestock farms and municipal treatment facilities.  The purpose of this study was to determine which combination of resources provided the most economically and environmentally sustainable process for growing feedstock for biofuels.
After analysis, Gopalakrishnan et al. concluded that for the first sample biorefinery, located near significant marginal land resources, marginal agricultural land provided the greatest percentage of feedstock requirements, but both roadway and riparian sites contributed percentages.  The sample biorefinery located far from marginal land resources obtained the highest percentage of feedstock requirements from minor roadway and riparian buffer sites, and very little from marginal agricultural land.  In both cases, using degraded water resources as irrigation significantly increased the percent yield of feedstock.  These results indicated that a systems approach to biofuels production can enable more croplands to be used for food production, reduce energy used for transportation by intensifying the biofuel potential of buffer sites, and reduce need for nitrate fertilizers by using degraded water as irrigation sources.  It was speculated that net greenhouse gas emissions would decrease with a systems approach to biofuel production because of the reductions in nitrous oxide emissions from fertilizer and from the increased carbon sequestration by biomass feedstock grown.  Further investigations in these areas need to be conducted, however Gopalakrishnan et al. concluded that a systems approach has the potential to improve the economic, social, and environmental sustainability of biofuels.

Sustainable biofuel production using composted urban waste as fertilizer

Biofuel production is a sustainable source of renewable power, however the use of nitrogen-heavy fertilizers greatly increases its net energy use and carbon dioxide emissions.  This study revealed that, by using composted waste from urban, municipal, and industrial sources as fertilizer for biomass feedstock, the environmental and economic sustainability of biofuel production could be greatly improved (Butterworth 2009). Jenny Ward

Butterworth, W. R. 2009. Sustainable biofuel production derived from urban waste using PSCC. Biofuels, Bioproducts, and Biorefining 3, 299–304

 The author uses the Bates family farm, a member of the Land Network group, as an example of a farm that relies on photosynthetic carbon capture and storage (PCCS) to reduce its net carbon emissions to almost zero by using urban ‘wastes’ as fertilizer for oilseed rape.  This crop is harvested using noninvasive practices and then converted into biodiesel, producing enough biofuel to satisfy all the energy needs of the farm.  The article compares the closed energy loops for different methods of turning crops into biofuels: using mineral fertilizers, using wastes, and using PCCS in soils.  Finally, nitrogen leakage levels from ‘controlled waste’ fertilizers were measured and compared among several other farm sites within the Land Network.
PCCS is a practical, economically feasible way to sustainably produce both biofuels and cash crops on a farm.  Ten percent of the Bates’ farm is dedicated to oilseed growth for biofuels production, and the other ninety percent of the land is used to harvest food crops.  About 300 tpa of ‘waste’ from local municipal and industrial sources can make 250 tonnes of compost, which is enough to fertilize 1 ha of oilseed rape.  In turn, this 1 ha of land can produce 1 tonne of biofuel, which when burned, emits 5 tonnes of CO2.  The PCCS process in the soil however, sequesters 70 tonnes of CO2, resulting in a net storage of 65 tonnes of CO2 in the ground, forming a carbon sink called a ‘humus’.  This facilitated process used on the farm mimics the naturally occurring process in the soil between hyphae and plant roots.
The waste sources are in close proximity to the farm, reducing logistics expenses and making this process more economic.  Also, the harvest produces all the biofuel the Bates’ need to power all their other processes on the farm, making the system environmentally sustainable.  Furthermore, at most farms the amount of nitrogen that leaks into the ground from the compost is negligible, especially when compared to the amounts leaked by mineral fertilizers.
Overall, the use of urban wastes as compost for sustainable biofuel production should explode as a renewable energy source, once restrictive environmental legislations are overcome and techniques to monitor the land onto which wastes are recycle are improved.

Varying emissions from buses using biodiesel in Madrid, Spain.

Lopéz et al. (2009) compared two types of emissions after-treatments on urban buses in Madrid.  The first treatment utilizes selective catalytic reduction (SCR) combined with urea, and the second uses exhaust gas recirculation (EGR) with a particulate filter.  The effects on greenhouse gas emissions of these two treatments were studied on buses using diesel fuel, fuel that is 20% biodiesel (B20), and 100% biodiesel fuel (B100).  Reductions in carbon monoxide (CO), carbon dioxide (CO2), unburned hydrocarbon (THC), nitrogen oxides (NOx), and particulate matter (PM) emissions, as well as fuel consumption varied according to treatment technology and fuel type. Jenny Ward
Lopéz, José María, and Felipe Jiménez, Francisco Aparicio, and Nuria Flores. 2009. On-road emissions from urban buses with SCR + Urea and EGR + DPF systems using diesel and biodiesel. Transportation Research Part D: Transport and Environment. 14, 1–5.

The authors used a driving cycle, designed by the Madrid Municipal Transit Company, which was developed for fuel economy and emission testing with on-board equipment.  The measurement device used was the Horiba OBS 2200, which collects data under real driving conditions.  Particulate matter amounts were measured using laser technology.  Measurements for each fuel type were obtained from five test runs within the driving cycle.
Lopéz et al. observed that between the two after-treatment technologies, SCR produced greater reductions in CO2 and NOx emissions, while EGR performed better according to CO and PM emissions reductions.  More importantly, varying trends were seen when diesel and biodiesel powered buses were compared.  Both the B20 and B100 fuels caused greater NOx and CO2 emissions and consumed more fuel than regular diesel buses, but the biodiesel buses did have a greater reduction in particulate matter emissions.  Despite increases in some greenhouse gas emissions, the authors recommend that biodiesel still be used as an alternative fuel source because “it is non-fossil, biodegradable, CO2 neutral and its combustion is sulphur oxide free”.

Cellulosic biofuel production is cost-effective when indirect greenhouse gas emissions are minimized.

Cellulosic biofuel is increasingly considered as a solution to meeting low carbon fuel standards (LCFS) in the 21st century, but there are costs and benefits, both economic and environmental, of biofuel production.  Melillo et al. assess the lifecycle costs of using biofuel as an energy source, including the effects of land-use changes, net fluctuations in both direct and indirect greenhouse gas (GHG) emissions, and measures of carbon intensity (CI), or according to the authors, the “simultaneous consideration of the potential of net carbon intake through enhanced management of poor or degraded lands, nitrous oxide (N2O) emissions that would accompany increased use of fertilizer, environmental effects on terrestrial carbon storage, and consideration of the economics of land conversion.”  Based on indirect emissions and CI data from two different scenarios of biofuel production, the process is beneficial only if existing managed land, rather than natural land, is used for the process as much as possible, and if N2O fertilizer use is managed properly.—Jenny Ward
  Melillo, Jerry M. et al. 2009. Indirect Emissions from Biofuels: How Important? Science 326, 1397–1399.

Jerry M. Melillo and colleagues compared two different cases of biofuel production.  The first case provided for the economically sound conversion of natural lands into biofuel growth sources; the second relied on existing managed land for biofuel production.  Using a computable general equilibrium (CGE) model and a processed-based terrestrial biogeochemistry model, Melillo et al. estimated the projected in changes in global land cover, the direct and indirect effects on projected cumulative land carbon flux, and the partitioning of greenhouse gas balance among fossil fuel abatement and fertilizer N2O emissions for each case.  In addition, they created a CI index that measured the accumulation and emission of direct land carbon, indirect land carbon, and fertilizer N2O during increasing time periods from 2000 to 2100.
Each observation revealed the benefits of producing biofuels using existing managed land rather than converting natural land to biofuel harvest.  Through this practice, less depletion of natural forests will occur in the upcoming century, which will in turn increase carbon sequestration by trees.  Furthermore, this decrease in deforestation coupled with increased use of pastures, shrubland, and savannah for biofuel production, will decrease the initial carbon accumulation and increase the eventual carbon sequestration.
Although initial increases in GHG emissions and carbon accumulation will occur in each cellulosic biofuel production land-use case, these negative effects precede eventual reductions in atmospheric carbon during the latter part of the century.  This occurs most significantly when existing managed land is reused, which minimizes the indirect emissions gains associated with more environmentally detrimental land-use changes.—Jenny Ward