WO2005056809A1

WO2005056809A1 - Method and device for microbial hydrogen production

Info

Publication number: WO2005056809A1
Application number: PCT/CA2004/002093
Authority: WO
Inventors: Basim Faraj
Original assignee: Faraj Consultants Pty Ltd.
Priority date: 2003-12-09
Filing date: 2004-12-09
Publication date: 2005-06-23
Also published as: CA2452786A1

Abstract

Hydrogen-producing bacteria are sealed in a favourable environment comprising coal, methane and water at temperatures of approximately 20 to 40°C. As the bacteria produce hydrogen, the hydrogen is periodically removed from the reaction container to maintain a disequilibrium and to ensure continued hydrogen production.

Description

Method and device for microbial hydrogen production

Field of the Invention

This invention relates to the production of hydrogen by microbes found in methane- saturated coal.

Background of the Invention

Hydrogen gas is used for a variety of industrial applications.

Pure hydrogen is rarely found in nature; it is typically present in combination with oxygen, carbon, or other elements. Current processes for producing hydrogen on an industrial scale include heating methane and steam to approximately 1100°C, and passing steam over iron oxide or cobalt oxide at approximately 400°C.

These processes are costly, in part due to the high energy requirements for heating to high temperatures. What is needed is a less costly and lower energy method for producing pure hydrogen.

In addition, known processes for producing hydrogen only yield at most 30% hydrogen, and accordingly a process for producing highly pure hydrogen is also needed.

Summary of the Invention

An object of this invention is to provide a less costly and more energy efficient process for producing hydrogen.

A further object of this invention is to provide a process for producing highly pure hydrogen. Hydrogen-producing bacteria are sealed in a favourable environment within a container such as an airtight aluminum canister, at temperatures of approximately 20 to 40°C. Coal and water are added as substrates for the bacteria. The water may be de-ionized. Methane is added or may be desorbed from the coal if it is naturally methane bearing, thus providing a reducing and anaerobic environment for the bacteria.

The bacteria are typically anaerobic, and may include bacteria from the genuses Vitreoscilla, Thermotoga and Xanthobacter that use coal as an energy source. Sources of the bacteria may include pond mud or pond water.

Hydrogen must be periodically removed from the reaction container to maintain a disequilibrium and ensure continued hydrogen production. The process can produce in the range of 84% hydrogen. The remainder of the gas produced is methane, and does not include undesirable products such as carbon dioxide.

In experimental procedures, volumes of 55 to 4430 cm³ of hydrogen were obtained, over periods of 70 to 260 days. Hydrogen production is continuous and the process has the potential to be scaled up for industrial applications. Little energy is consumed during hydrogen production.

According to the present invention then, there is provided a process for producing hydrogen comprising the steps of placing hydrogen-producing bacteria in a container under suitable temperature and pressure conditions; placing a suitable substrate in said container; and periodically removing hydrogen from said container.

Brief Description of the Drawings

Figure 1 is a cross-section of a suitable reaction container for producing hydrogen according to the present invention; and Figure 2 is a perspective view of an alternative reaction chamber for the production of hydrogen.

Detailed Description of the Preferred Embodiments

In Figure 1 , the bacteria, coal 8, methane and water 3 are placed inside a sealable container 1. The coal can be placed within a sleeve 2 of plastic film or other material to physically support the coal within the container. The sleeve and the coal can then together be placed into container 1 in which they are submerged in de-ionized water

3. It is unknown whether the sleeve makes any contribution to the production of the hydrogen. The temperature inside container 1 is monitored with a temperature probe

4, while pressure is monitored with a pressure gauge 5. A thermocouple 6 permits the container to be heated, and a valve 7 allows the pressure to be adjusted and gas to be released.

One suitable container is an aluminum desorption canister having a volume of 2400 cm³, a diameter of 14 cm, and a length of 37cm. When scaled up for industrial purposes, larger containers enclosing greater volumes of coal will likely be used.

Figure 2 illustrates an alternative reaction chamber 10 which is cuboidal in shape so that the coal 8 is disposed in a bed-like layer with water 3 wholly or partially submerging the coal. Cam locks 13 are used to retain a removable lid 11 in place to form a leak and pressure resistant seal with the remainder of the chamber. The chamber includes a pressure gauge 5 and one or more valve 7 are provided for the ingress of methane and/or the release of produced hydrogen. The chamber can additionally include a temperature probe and a thermocouple as required.

Example 1

Coal samples, either cuttings ranging from a few millimetres to a few centimetres in diameter, or core samples with a diameter of 50mm and a length of 30cm were placed within plastic sleeve 2 and then placed inside desorption canister 1. Water was added to fill the canister to the 70% to 80% level and the canister lid is then closed tightly. The space in the canister above the water is the area where produced gas can accumulate between ventings.

Bacteria were added to the coal by obtaining 2-3 g of pond mud or bacteria- containing water from a reserved collection. The canister was sealed and the canister's interior and the coal samples therein were then saturated with industrial grade methane gas (commercially available in pressurized cylinders) introduced through valve 7. In the alternative or in addition to adding methane, the coal itself, if methane bearing, will desorb the methane into the canister to initiate a reducing environment.

After being sealed, the canister was placed in a water bath , with water temperatures between 20 and 40°C. Every 24 hours, the canister was vented through valve 7 to release some gas and reduce the pressure to 10psi in order to maintain a disequilibrium and enable the bacteria to continue generation of hydrogen.

After 1 -2 weeks, a gas sample was analysed to verify hydrogen presence and purity.

The above-described embodiments of the present invention are meant to ^■ be illustrative of preferred embodiments and are not intended to limit the scope of the present invention. Various modifications, which would be readily apparent to one skilled in the art, are intended to be within the scope of the present invention. The only limitations to the scope of the present invention are set forth in the following claims appended hereto.

Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A process for producing hydrogen comprising the steps of: placing hydrogen-producing bacteria in a container under suitable temperature and pressure conditions; placing a suitable substrate in said container; and periodically removing hydrogen from said container.

2. A process as claimed in claim 1 , wherein said substrate comprises coal.

3. A process as claimed in claim 2, wherein said substrate additionally comprises water.

4. A process as claimed in claims 2 or 3 wherein said substrate additionally comprises methane.

5. A process as claimed in claim 4 wherein said methane is desorbed from said coal.

6. A process as claimed in claims 1 to 5, wherein said temperature conditions are between 20°C and 40°C.

7. A process as claimed in any of claims 1 to 6 wherein said pressure in said container after said periodic removals of said hydrogen is about 10 psi.

8. A process as claimed in claim 2, wherein said coal contains methane therein.

9. A process as claimed in any of claims 1 to 8 wherein said bacteria are from the genuses Vitreoscilla, Thermotoga or Xanthobacter.