Renewable and Non-Renewable Exergy Costs and CO2 Emissions in the Production of Fuels for Brazilian Transportation Sector

Daniel Flórez-Orrego, Julio A. M. da Silva, Héctor Velásquez, Silvio de Oliveira Jr.

Renewable and Non-Renewable Exergy Costs

and CO2 Emissions in the Production of Fuels for

Brazilian Transportation Sector

ECOS 2014 - THE 27TH INTERNATIONAL CONFERENCE ON

EFFICIENCY, COST, OPTIMIZATION, SIMULATION AND ENVIRONMENTAL IMPACT OF ENERGY SYSTEMS

JUNE 15-19, 2014, TURKU, FINLAND

Polytechnic School, University of São Paulo, São Paulo, Brazil

Faculty of Mines, National University of Colombia, Medellin, Colombia

Polytechnic School, Federal University of Bahia, Salvador, Brazil

Universidade de São Paulo

INTRODUCTION

• Transportation sector: Important issue across the global economy.

• The quest for higher energy efficiencies through the advent of new technologies can also alter the

vehicle demand profiles, as well as modify the levels of emissions and fuel consumption.

• The dependence of petroleum-derived fuels is forecast to decline. However, the extent to which

alternative fuels can make the fossil fuel substitution will depend largely on how they are produced.

• Brazilian electricity generation and transportation sector mixes have been characterized by an

approach that is peculiar within the international context of dependence on fossil fuels.

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METHODOLOGYSupply stage

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METHODOLOGYTransformation stage

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METHODOLOGYEnd Use stage

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PETROLEUM AND NATURAL GAS ROUTE

Offshore Oil & Gas FPSO unit (Campos basin).

Transportation Oil: Suezmax shuttle tanker, pipeline (electricity),

Natural gas: pipeline (gas turbines to drive the compressors).

Refinery: cracking-coking scheme configuration (Silva and Oliveira Jr., 2014).

For electricity generation, two different power plants are used (NG.C.C. and ICE )

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PETROLEUM AND NATURAL GAS ROUTES7/16

Percentage distribution of destroyed exergy

at the refinery

328.25kgCO2/m3 for gasoline and 63.13kgCO2/m3 for

straight diesel oil (~5 times!): Further processing.

Highly endothermic, steam methane reforming (SMR)

process and large CO2 emissions in reforming and shift

reactions of hydrogen generation.

Natural Gas 1.1167 0.0189 1.0978 0.0049 0.0172




Sugar cane ethanol production. Bagasse is 83% of total biomass for electricity generation.

Non-renewable energy consumption 147 kJ/MJethanol: Natural Gas 27%, Diesel 73% (Macedo, 2008).

Anhydrous ethanol yield 68.3 kg/tc (86.3 L/tc).

Sugar-ethanol/Cogeneration plant: bagasse-fired boilers and backpressure steam turbines

(22bar/300°C). Electricity surplus of 9.2kWh/tc.

BIOMASS-DERIVED ELECTRICITY & ETHANOL ROUTE8/16




BIOMASS-DERIVED ELECTRICITY & ETHANOL ROUTE9/16


• Typical cogeneration power plant efficiencies achieve

15-17%.

• Fermentation process: Low efficiency of chemical

reaction and high CO2 production (21.2%).

• Washing and Milling process: Sucrose loss in the

bagasse; Direct driving turbines (5.8%).

• Utilities plant: Irreversible chemical reactions, biomass

is burnt as fuel (62%).

300.12kgCO2/m3ethanol




(270 - 340 kgCO2/m3)

Chemical composition of FFB is used to calculate the chemical exergy (16268kJ/kg FFB) and φ value

(1.0736) of FFB.

Herbicides and irrigation systems make only a small contribution to the energy consumption. Non-

renewable energy consumption 2.85MJ/kgbiodiesel: Natural Gas 29%, Diesel 71% (Costa et al, 2006).

Methanol-based transesterification process is considered.

BIODIESEL ROUTE11/16




BIODIESEL ROUTE12/16


cR = 1.0996 kJ/kJbiodiesel

cNR = 0.4084 kJ/kJbiodiesel

cCO2 = 0.0249 gCO2/kJbiodiesel or 866 kgCO2/m3biodiesel

Other studies: Font de Mora et al. (2012), Cavalett e

Ortega (2010)

cR/cNR = 2.69

Oil extraction and biodiesel production units: High

efficiency of oil extraction and transesterification

processes.

Utilities plant: Highly irreversible process (biomass-

fired boilers)




BRAZILIAN ELECTRICITY MIX

(Flórez-Orrego et al, 2014)

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cR = 1.4627 kJ/kJe

cNR = 0.3328 kJ/kJe

cCO2 = 62.63 gCO2/kWh




Comparison between the renewable and non-renewable unit exergy costs and CO2

emission cost of the different fuels used in transportation sector.

RESULTS AND DISCUSSION13/16




0,001 2,69 15,96 4,39 0,018cR/cNR

CONCLUSIONS

• Fossil fuels require the lowest exergy investment for the entire production route. However, the

renewable fraction of invested exergy is almost negligible. CO2 emission cost will depend on the level

of processing of the fuel.

• Subsidies and governmental policies, higher efficiencies of cogeneration power plants and

defossilization of the exergy consumption at the upstream stages are required as renewable fuels

scale up. In this way, lower unit exergy costs and CO2 emissions could be achieved.

• The ratios between the renewable to non-renewable invested exergy (cR/cNR) are obtained as 2.69

for biodiesel, 4.39 for electricity, and 15.96 for ethanol.

• Regarding hydrogen used as a transport fuel, as far as it depends on fossil fuels for its production,

the cost-to-benefit and environmental impacts suggest that other fossil sources such as natural gas or

petroleum derivatives may accomplish a better performance.

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ACKNOWLEDGMENTS

National Agency of Petroleum, Natural Gas and Biofuels – ANP

National University of Colombia – Faculty of Mines

Brazilian National Research Council – CNPq

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THANKS FOR YOUR ATTENTION !!!

Kiitos huomiota

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EXTENDED ROUTES7A




Biodiesel Route

EXTENDED ROUTES8A




Petroleum Refinery

EXTENDED ROUTES9A

Combined Ethanol,

Sugar and Electricity

Production plant.

Renewable and Non-Renewable Exergy Costs and CO2 Emissions in the Production of Fuels for Brazilian Transportation Sector

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