Green Car Congress  
Go to GCC Discussions forum About GCC Contact  RSS Subscribe Twitter headlines

« 2005 US Salary Increases Go Into the Tank | Main | EPA Publishes 2006 Fuel Economy Guide; Total Average Economy Decreases »

Print this post

XCel Funds Further Development of Ovonic Biofuel to Hydrogen Process

12 October 2005

Ovonic Battery Company, a subsidiary of Energy Conversion Devices (ECD Ovonics), has been awarded a $900,000 contract by Xcel Energy to support R&D of a new base-facilitated process for reforming renewable fuels, such as bioethanol and biomethanol, to produce hydrogen for use in fuel cells or engines.

This fundamentally new approach to hydrocarbon reforming dramatically reduces the required reaction temperature and avoids the generation of CO2 as a byproduct.

The reforming process can thereby become potentially simpler and cheaper (both in operating cost and capital investment); less energy-intensive; and cleaner. The program funded by Xcel will transfer this process from research to pilot level, examining the commercialization feasibility from both a technical and an economic perspective.

The Ovonic process, around which it has filed a number of patent applications, uses the chemical or electrochemical reactions of biofuels (or other biomass or carbonaceous materials—e.g., coal) with bases in which carbonate and/or bicarbonate compounds are produced as a by-product.

The process includes a carbonate or bicarbonate recycling process in which the carbonate or bicarbonate by-product is transformed to a base that can subsequently be further reacted with the feedstock to produce hydrogen.

Using a thermodynamic analysis, the Ovonic researchers determined that many hydrocarbons and oxygenated hydrocarbons react spontaneously with a base or basic aqueous solution to form hydrogen gas at less extreme conditions than those in steam reformation reactions.

In some of their work, the process led to the formation of hydrogen gas from a liquid phase reaction mixture, in some cases at room temperature, where hydrogen was the only gaseous product and thus was readily recoverable without the need for a gas phase separation step.

Furthermore, the reactions operate through the formation of carbonate ion or bicarbonate ion and thus avoid the production of the greenhouse gases CO and CO2.

In short, the inclusion of a base creates a new reaction pathway for the formation of hydrogen gas at lower temperatures than are needed for corresponding steam reformation processes and without the generation of CO2.

Reactions for the Reforming of Ethanol (C2H5OH) into Hydrogen
ReactionΔ G
Source: Ovonic Battery Company
(1) C2H5OH(l) + 3H2O(l) → 6H2(g) + 2CO2(g) 23,950
(2) C2H5OH(l) + 2OH-(aq) + 3H2O(l) → 6H2(g) +2HCO-(aq) 7,040
(3) C2H5OH(l) + 4OH-(aq) + H2O(l) → 6H2(g) +2CO32-(aq) -2,970

As an example of the work, in the table above, reaction (1) represents the conventional reforming of ethanol and reactions (2) and (3) represent base-facilitated reformation reactions according to the Ovonic process.

Reactions (2) and (3) differ with respect to the relative amounts of hydroxide ion and ethanol.

Δ G is the Gibbs free energy of reaction for each of the reactions at standard conditions (25º C, 1 atmosphere and unit activity of reactants and products). Gibbs free energy is an indicator of the thermodynamic spontaneity of a chemical reaction. The more negative (or less positive) the Gibbs free energy is, the more spontaneous is the reaction.

The conventional reformation reaction (1) is a non-spontaneous reaction at standard conditions. The base-facilitated reformation reaction (2) is also non-spontaneous, but is more spontaneous than reaction (1) (and would become spontaneous at a lower temperature than reaction (1)).

Put another way, the first base-facilitated reaction is less non-spontaneous than the conventional reformation reaction. Further addition of base leads to a further decrease in the Gibbs free energy and ultimately provides a spontaneous reaction at standard conditions as exemplified by reaction (3) above.

The process can, in principle, be applied to a wide range of feedstocks, some of which will clearly perform better than others.

Xcel Energy is a major US electricity and natural gas company with regulated operations in 10 Western and Midwestern states. In terms of customers, it is the fourth largest combination natural gas and electricity company in the nation.

Resources:

October 12, 2005 in Bio-hydrogen, Biomass, Ethanol, Hydrogen, Research | Permalink | Comments (2) | TrackBack (0)

TrackBack

TrackBack URL for this entry:
http://www.typepad.com/services/trackback/6a00d8341c4fbe53ef00d83466a29d53ef

Listed below are links to weblogs that reference XCel Funds Further Development of Ovonic Biofuel to Hydrogen Process :

Comments


"Furthermore, the reactions operate through the formation of carbonate ion or bicarbonate ion and thus avoid the production of the greenhouse gases CO and CO2"

I'm not sure what this means. Carbonate and bicarbonate are just dissolved forms of CO2, so they're still producing 1 CO2 for every carbon that goes in. If the base is provided as Ca(OH)2 or something similar that will precipitate the carbonate (in that case as CaCO2), the CO2 won't be released as gas, but that seems to me to be different from not produced. Mineralization of CO2 as carbonate salts is well-known as a strategy for sequestration.


Correction: the precipitated carbonate should be CaCO3, not CaCO2.

Addendum: according to the patent app, the carbonate recycling process referred to in the article is thermal decomposition of the metal carbonate to the metal oxide, which is hydrated to the metal hydroxide, ie:

CaCO3 --> CaO + CO2
CaO + H2O ---> Ca(OH)2

So if the base is recycled, then the carbonate is deliberately converted to gaseous CO2.

None of this takes away from the fact that it might be a viable method for producing hydrogen easily, but don't present it as a non-CO2 producing alternative.

Verify your Comment

Previewing your Comment

This is only a preview. Your comment has not yet been posted.

Working...
Your comment could not be posted. Error type:
Your comment has been posted. Post another comment

The letters and numbers you entered did not match the image. Please try again.

As a final step before posting your comment, enter the letters and numbers you see in the image below. This prevents automated programs from posting comments.

Having trouble reading this image? View an alternate.

Working...

Post a comment

Green Car Congress © 2014 BioAge Group, LLC. All Rights Reserved. | Home | BioAge Group