Presentation on theme: "1 Biofuels as an alternative to traditional transportation fuels: Chemist's Perspective Ole John Nielsen and Vibeke Friis Andersen Department of Chemistry,"— Presentation transcript:
1 Biofuels as an alternative to traditional transportation fuels: Chemist's Perspective Ole John Nielsen and Vibeke Friis Andersen Department of Chemistry, University of Copenhagen Copenhagen June 10 th 2011
2 Acknowledgements Tim Wallington (FORD) Sherry Mueller (FORD) Jim Anderson (FORD) Mads Andersen (NASA) The CCAR group $$$: Danish Natural Science Research Council $$$: Villum Kahn Rasmussen Foundation $$$: EUROCHAMP2
3 What features do we desire in a vehicle fuel? 1.Cheap, either already abundant in nature, or easy to make 2.Fuel and spent fuel should be easy and safe to handle (i.e., liquid or gas [not solid] over “typical” temperature operation range of -20 to +40 o C and no reaction with air or water under ambient conditions) 3.For a chemical fuel we need at least two reactants. Inefficient to carry more than one reactant on vehicle/plane, best to use atmosphere as second reactant. Atmosphere is 78% N 2, 21% O 2, 1% Ar. N 2 is poor reactant (N≡ N bond too strong), Ar is unreactive, leaves O 2 4.Fuel should have highly exothermic reaction with O 2 but not at ambient temperature (kinetics and thermochemistry) 5.High energy density. 6.Environmentally benign, renewable and the oxide(s) should be benign
4 Periodic Table
5 Exclude elements that: (i) have solid oxides
6 Periodic Table Exclude elements that: (i) have solid oxides, (ii) do not have highly exothermic reaction with oxygen
7 Periodic Table Exclude elements that: (i) have solid oxides, (ii) do not have highly exothermic reaction with oxygen, (iii) have toxic oxides
8 Periodic Table Conclusion: hydrogen and carbon are likely to be the two most important elements in transportation fuels.
9 Periodic Table Conclusion: hydrogen and carbon are likely to be the two most important elements in transportation fuels and oxygen will do no harm
10 2. Motivation for biofuels - Sustainability Sustainabilty: Economic, Environmental Social sustainability Biofuels address: Energy security Climate Change Support for rural communities Proven oil reserves. Source: BP
11 3. Biofuel History- Biofuels are not new Ford’s vision was to “build a vehicle affordable to the working family and powered by a fuel that would boost the rural farm economy.” 1908 – Ford Model T introduced Around First Flexible Fuel Model T Vehicle - (low compression engine, adjustable carburetor, and spark advance allowed use of gasoline, ethanol, or blends) "All the world is waiting for a substitute for petrol. The day is not far distant when, for every one of those barrels of petrol, a barrel of ethanol must be substituted.” – Henry Ford
s Gasoline was motor fuel of choice; 6-12% ethanol added for anti-knock Vehicle Ethanol: Rise and Fall 1940s Low-priced, Middle-East oil 1937 Ford supported ethanol for fuel. Ethanol blends account for 25% of sales in Midwest 1920s Tetraethyl lead added for anti-knock 2000s MTBE phased-out due to environmental concerns; Crude oil price more than doubled (~$30/bbl to $80+/bbl) 2005 U.S. oil imports accounted for 70% of consumption, U.S. Energy Policy Act mandated 7.5 billion gallons of renewable fuel use by President Bush announced 35 billion gallons alternative fuel goal (2017). Ethanol production capacity was billion gallons by s World energy crisis; Leaded gas phased-out; US subsidies for ethanol blends 1978 MTBE became oxygenate of choice; 1980s Excess oil capacity caused drop in crude oil price
13 Biofuel are many different things first, second and third generation… / butanols
14 a OECD-SG/SD/RT(2007)3 4. Will biofuels survive this time? 2005: 0.8 EJ (1% of the total road transportation fuel) 2010: 2-3% of rtf 2050: 20 EJ from first generation biofuels (11% rtf) a 2050: 23 EJ from second generation biofuels (12% rtf) a Says 27% in 2050 (a ref – but no ref….)
Mha (Tot land 0.8 Gha) 520 Mha (Tot land 2 Gha) 730 Mha (Tot land 1.6 Gha) 620 Mha (Tot land 1 Gha) 730 Mha (Tot land 2 Gha) 1290 Mha (Tot land 3.4 Gha) 140 Mha (Tot land 0.3 Gha) 360 Mha (Tot land 1.9 Gha) Assumptions: 100 EJ from energy crops (0.5 Gha, 10 t/ha, 20 GJ/t) 100 EJ from waste material (e.g. straw, sawdust, manure, MSW) Global biomass supply potential converted into biofuel could satisfy approximately 20-30% of projected global transportation energy needs in 2050 Global total land ~13 Gha Global arable and pasture land ~4.85 Gha Source: Maria Grahn, Chalmers University (2007)
16 5. The Atmospheric Chemistry One example: iso-butanol Reaction with OH radicals is the most important atmospheric reaction Determine the OH rate constant and the degradation products V. F. Andersen, T. J. Wallington, O. J. Nielsen: “Atmospheric Chemistry of i-butanol”, J. Phys. Chem. A 114, (2010)
17 Experimental Techniques Smog chamber with FTIR 1. Cl 2 +hν→2Cl 2. CH 3 ONO+hν CH 3 O + NO CH 3 O + O 2 HCHO + HO 2 HO 2 + NO OH + NO 2
18 OH radical kinetics OH + (CH 3 ) 2 CHCH 2 OH → products(9) OH + C 3 H 6 → products(10) OH + C 2 H 4 → products(11) Linear least squares analysis gives k 9 /k 10 = 0.41±0.04 and k 9 /k 11 = 1.41±0.10. Using k 10 = 2.63 x and k 11 = 8.52 x gives k 9 = (1.08 ± 0.11) x and (1.20 ± 0.09) x cm 3 molecule -1 s -1. Hence k 9 = (1.14±017) x Reaction with OH radicals is the major atmospheric loss process for (CH 3 ) 2 CHCH 2 OH Combined with [OH]=1x10 6 Gives lifetime ~ 1 day
19 OH radical kinetics Oxidation kinetics of i-butanol are well established.
20 OH radical oxidation products OH radical initiated oxidation gives CH 3 C(O)CH 3 in a molar yield of 61 ±4%. Experimental data are indistinguishable from the result (57%) predicted using structure activity relationships and assumed in atmospheric models.
21 57% 61% 4%37%SAR: Results are consistent with model assumptions
22 Conclusions Biofuels can address climate change and energy security. –Biofuels not a wonder solution, but could make an important 10-30% contribution to the transportation sector. –Incorporating biofuels into transportation fuels requires adherence to fuel specifications. –Implementing a biofuels strategy requires the consideration of vehicle compatibility for optimal performance –Provide support for rural communities (i.e. social benefit) Second and “third” generation biofuels needed. –Many ways to make biofuels, good ways and bad ways, encourage the good ways (certification perhaps?) –Modern biofuel science in its infancy – future contribution of biofuels to transportation fuel pool is unclear Environmental impacts (atm chem) of potential biofuels must be quantified/investigated Food vs Fuel issues? Need to address CO 2 from all sectors
23 We have a lot to roar about Thank you for your attention Transportation biofuels present interesting questions - It’s a great time to be an atmospheric chemist
24 Extra slides
25 Food vs Fuel?
26 Many potential second generation biofuels – need research.
27 Externalities of biomass growth and biofuel production will be magnified as scale increases. Many factors must be considered for scale-up of first generation and development of second generation. Economics –Feedstock price and transport –Processing –Land use changes Food prices Natural habitat, biodiversity Environmental properties (LCA) –Petroleum reduction –Greenhouse gas reduction –Other resources Properties as fuels
28 Need to address CO 2 in all sectors. On-road light-duty car and trucks contribute about 20% of US, 17% of EU-15, and 11% of global fossil fuel CO 2 emissions. T. J. Wallington, J. L. Sullivan, and M. D. Hurley, Emissions of CO2, CO, NOx, HC, PM, HFC-134a, N2O and CH4 from the Global Light Duty Vehicle Fleet, Meteorol. Z., 17, 109 (2008)
33 FTIR SMOG CHAMBERS 140 L Pyrex chamber black-lamps 296 K Torr FTIR-detection 100 L Quartz chamber UVA, UVA and sunlamps K Torr FTIR-detection
34 UV irradiation of: – compound X/reference/CH 3 ONO/NO/air (reference = C 2 H 2 or C 2 H 4 ) CH 3 ONO + hν CH 3 O + NO CH 3 O + O 2 HCHO + HO 2 HO 2 + NO OH + NO 2 OH + compound X products OH + reference products
35 Biodiesel model compound CH 3 (CH 2 ) 7 CH=CH(CH 2 ) 7 C(O)OCH 3 from oleic acid, C 15 H 31 C(O)OCH 3 from palmitic acid Energy density Biodiesel is composed of esters of fatty acids (typically methyl esters) and is made via a relatively simple trans-esterification process from tri-acyl- glycerides. Esters because of cold flow properties. Prior to the use of such acylated glyercine derivatives, information on their atmospheric chemistry and hence environmental impact is required. CH 3 C(O)O(CH 2 ) 2 OC(O)CH 3, ethylene glycol diacetate, as a model compound for such acylated glycerine molecules.
36 CH 3 C(O)O(CH 2 ) 2 OC(O)CH 3
37 OH + CH 3 C(O)O(CH 2 ) 2 OC(O)CH 3 → products(4) OH + C 2 H 4 → products (5) OH + C 2 H 2 → products (6) Linear least squares analysis gives k 4 /k 5 = 0.28 ± 0.03 and k 4 /k 6 = 2.8 ± 0.3. Using k 5 = 8.7 x and k 6 = 8.45 x , we derive k 4 = (2.4 ± 0.3) x cm 3 molecule -1 s -1. Atmospheric lifetime of approx. 5 days
38 CH 3 C(O)OH CH 3 C(O)OC(O)H CH 3 C(O)OC(O)CH 2 OC(O)CH 3 Closed symbols: 5 Torr O 2 Open symbols: 700 Torr O 2 Mechanism?
39 UV irradiation of: – CH 3 CH 2 CHOHCH 2 CH 3 /reference/CH 3 ONO/NO/air (reference = C 2 H 2 or C 2 H 4 ) CH 3 ONO + hν CH 3 O + NO CH 3 O + O 2 HCHO + HO 2 HO 2 + NO OH + NO 2 OH + CH 3 CH 2 CHOHCH 2 CH 3 products(4) OH + reference products(5/6)
40 OH + CH 3 CH 2 CHOHCH 2 CH 3 → products(4) OH + C 2 H 4 → products(5) OH + C 3 H 6 → products(6) Linear least squares analyses give k 4 /k 5 = 1.6 ± 0.05 and k 4 /k 6 = 0.46 ± 0.03 Using k 5 = 8.52 x and k 6 = 2.68 x , we derive k 4 = (1.3 ± 0.1) x cm 3 molecule -1 s -1. Gives an atmospheric lifetime for 3-pentanol of around 1 day. Previously published value k = (1.2 ± 0.3) × 10 ‑ 11 cm 3 molecule ‑ 1 s ‑ 1. Structure activity relationship (SAR) prediction of 1.13 x cm 3 molecule -1 s -1 with 90% of the predicted reactivity is on the central carbon atom. No product studies have been reported.
41 As in the case of OH, a significant fraction of the Cl reactivity is expected to take place at the central C atom: CH 3 CH 2 CHOHCH 2 CH 3 + Cl → α(CH 3 CH 2 C. OHCH 2 CH 3 ) + HCl(1) CH 3 CH 2 C. OHCH 2 CH 3 + O 2 → CH 3 CH 2 C(O)CH 2 CH 3 + HO 2 (100%) We expect to observe a significant yield of 3- pentanone as one of the products in the reaction of 3-pentanol with Cl atoms in the presence of O 2. 3-pentanone also reacts with Cl atoms, k Cl =8.1x cm 3 molecule -1 s -1. The corresponding rate equation can be solved analytically to relate the concentration of 3- pentanone to the conversion of 3-pentanol. The curve through the data is a fit of the expression above to the data which gives α = 42%. There is some fundamentals to be learned!
42 Biofuel – future 2005: 0.8 EJ (1% of the total road transportation fuel) 2050: 20 EJ from first generation biofuels (11% rtf) 2050: 23 EJ from second generation biofuels (12% rtf)
43 Biofuel – future Energy security/availability US consuming and importing more energy than ever before Shrinking petroleum reserves Political unrest in oil-producing regions High (and unstable) petroleum prices
44 20% of the US corn harvest in 2006 was used to produce ethanol, but that ethanol replaced only 2.4% of gasoline consumption (equivalent to an average blend of E3.6). Second-generation biofuels are needed. First-Generation Biofuel: Corn Ethanol
45 Displacement of substantial fraction of petroleum requires development of second generation biofuels. Biofuels are not likely to replace petroleum entirely, but they could displace 10, 20, or 30% of U.S. gasoline use in next few decades through use of B5, E10, and E85. Biofuels are generally more expensive than fossil fuels. Mandates/subsidies will probably be required.
46 Biofuels close the carbon cycle by recycling atmospheric CO 2. Degree of closure depends on fuel and process (lifecycle analysis). Solar energy Biomass growth Biofuel production Use in vehicle Land use changes Food prices Resource use (energy, water, chemicals) Biodiversity All biofuels are not created equal
47 Proven oil reserves at end 2004 Source: 2005 BP Energy review
48 Population Growth to Billion People in 2050 Per Capita GDP Growth at 1.6% yr -1 Energy consumption per Unit of GDP declines at 1.0% yr -1
: 14 TW 2050: 28 TW Total Primary Power vs Year
50 Prerequisites The stone age did not end for the lack of stone And the oil age will end long before we run out of oil Transportation biofuels are going to be around – for what ever reasons What are transportation biofuels going to be ? -(if you read the papers) Bioethanol and biodiesel ? But look at what plants are made of ? Biorefinery at College Station, Texas makes mixed alcohols from biomass
The big picture Atmospheric chemistry Ozone and secondary organic aerosols The Chemist’s picture Light harvesting Mircroorganisms Enzymes (Artificial)
54 Would it be possible to get bio C 3, C 4, C 5 oxygenated compounds and burn then in engines? BP and Dupont initiative Vehicle manufactures would like oxygenates that do not require big changes Bioethanol? But look at what plants are made of?
55 Regardless, commitment from government, industry, and consumers is needed to ensure long-term viability of modern biofuel industry. Agriculture Biofuels can benefit rural economies Will biofuels survive this time? Climate change Biofuels can reduce GHG emissions by recycling atmospheric CO 2
56 Conclusions (2) Biofuels should be derived from “non-food crops” –Second and “third” generation biofuels needed. –There will always be indirect energy-food competition through the competition for land. If the climate issue is more important than the energy security issue- then biomass should be burned and not converted Potential unintended consequences should be avoided (Crutzen, ACPD 7 (2007) 11191) Different numbers are flying all over the place –Biofuel “science” is “new” Time of great uncertainty and great opportunity, more research and development needed.