Study finds autothermal reforming with WGS reactor preferred option for on-board reforming of biodiesel and bioethanol
25 December 2010
A study by a team at the German Aerospace Center (Deutschen Zentrums für Luft- und Raumfahrt, DLR) identified autothermal reforming in combination with a water gas shift reactor as the preferred option for on-board reforming of biodiesel and bioethanol into a hydrogen-rich gas suitable for high temperature PEM (HTPEM) fuel cells.
The paper by Stefan Martin and Antje Wörner, published online in the Journal of Power Sources, investigated steam reforming (SR) and autothermal reforming (ATR) options for the on-board conversion of bioethanol and biodiesel using the simulation tool Aspen Plus, with a special emphasis on thermal heat integration.
Methyl-oleate (C19H36O2) is chosen as reference substance for biodiesel. Bioethanol is represented by ethanol (C2H5OH). For the steam reforming concept with heat integration a maximum fuel processing efficiency of 75.6% (76.3%) is obtained for biodiesel (bioethanol) at S/C = 3. For the autothermal reforming concept with heat integration a maximum fuel processing efficiency of 74.1% (75.1%) is obtained for biodiesel (bioethanol) at S/C = 2 and λ = 0.36 (0.35). Taking into account the better dynamic behaviour and lower system complexity of the reforming concept based on ATR, autothermal reforming in combination with a water gas shift reactor is considered as the preferred option for on-board reforming of biodiesel and bioethanol. Based on the simulation results optimum operating conditions for a novel 5 kW biofuel processor are derived.
—Martin and Wörner
Resources
Stefan Martin and Antje Wörner (2010) On-board reforming of biodiesel and bioethanol for high temperature PEM fuel cells: Comparison of autothermal reforming and steam reforming. Journal of Power Sources doi: 10.1016/j.jpowsour.2010.11.100
Wet ethanol could also be used, at a 20% savings in energy manufacturing it..
Posted by: Herm | 25 December 2010 at 10:19 AM
Since water is produced by the fuel cell, the gas shift should require none. Wet ethanol makes sense and so does synthetic ethanol which requires no drying.
Once they get the cost down and reliability up for fuel cells, they could be a factor. They have reduced the amount of platinum required and are setting goals to require no more than that used in a catalytic converter.
Posted by: SJC | 25 December 2010 at 10:59 AM
Interesting development but it would still use liquid fuels.
Could NG, LNG and/or SG be used instead of liquid fuels?
Posted by: HarveyD | 26 December 2010 at 08:06 AM
“In 2003, Lanny Schmidt, a professor of chemical engineering and materials science at the University of Minnesota, demonstrated a reformer that transformed a solution of 60% ethanol 40% water into hydrogen. This was funded by the National Science Foundation (NSF), the Department of Energy (DOE), and the Initiative for Renewable Energy and the Environment at the University of Minnesota. Schmidt authored "Renewable Hydrogen from Ethanol by Autothermal Reforming," Science, February 13, 2004.
One observation he made was remarkable:
Not only was all the hydrogen in the ethanol extracted – So was HALF of the hydrogen in the water.”
For those who are interested in advanced ethanol-water engine and fuel cell technologies, including auto-thermal reforming:
https://sites.google.com/site/e1004freeread/
Posted by: Aureon Kwolek | 26 December 2010 at 11:18 AM
Modern PEM fuel cells are operating at temperatures above the boiling point of water, which makes the balance of plant equipment smaller and less expensive. They are less susceptible to CO poisoning of the catalyst, so reformers can be smaller and less expensive.
Liquid fuel has good energy density. We have pipelines, tank farms and tanker truck already set up to deal with liquid fuels. You can reform natural gas and hence SNG at the fueling station or you can reform it on the vehicle. That could be the best delivery system of all.
Posted by: SJC | 26 December 2010 at 12:52 PM
Why even consider fuel cells that require hydrogen. Compression engines (diesel) can get a better overall efficiency running on bio-fuels or any liquid fuel than a combination reformer and fuel cell at far less capital cost. Large ship engines can get 50 percent of the energy put into the shaft directly from the piston and another 10 percent with a steam turbine operated from the exhaust heat. Similar results can be had from a range extender engine optimized for efficiency. The cost of the reformer and fuel cell is far more than the cost of an engine and battery. ..HG..
Posted by: Henry Gibson | 27 December 2010 at 01:52 AM
While the reformer/fuel cells would emit CO2, they do not emit combustion products. They are quiet and clean.
Posted by: SJC | 27 December 2010 at 12:23 PM