AU2006100045A4 - Photobioreactor for mitigation of greenhouse gases - Google Patents

Description

0 Photobioreactor for mitigation of greenhouse gases 0 0 D Rising levels of greenhouse gases are causing concern around the world. The primary source of greenhouse gases coming from the burning of fossil fuels, with t the majority burnt in coal based power stations. What can be done to reduce these gases? 0 One solution is to use Blue-green algae. Blue-green algae are known as the fastest growing organism to utilize photosynthesis. The process of I' photosynthesis involves water, nutrients, several greenhouse gases, and light to o cause chemical reactions within the organism enabling the energy from the light o to be stored in chemical bonds such as hydrocarbons. The algae can then be O used to produce hydrocarbon fuels.

O This invention relates to a photobioreactor enabling effective cultivation and o harvesting of a blue-green algae solution. It is designed to maximize the exposure of flue gases (from the burning of carbon based fuels) and light to a blue-green algae solution, effectively removing a majority of greenhouse gases from the flue gases.

The photobioreactor design in this invention consists of the following components: A vertical coil of transparent or semi-transparent tubing joined at top and bottom via a tube or tank so as to provide a system through which a solution of blue-green algae, water, nutrients and gas can circulate.

A tap at the base of the photobioreactor to allow the solution to be drained off and harvested or cleaning of the photobioreactor.

A gas inlet into the tubing, connected at the base of the coil, above the tap so that gas rises up through the solution in the tubular coil.

A gas outlet at the uppermost point of the photobioreactor.

A method of temperature control for the photobioreactor, by controlling the temperature of the gas to the gas inlet.

The tubing is in a coil shape so as to maximize the exposure of the gas from the inlet to the blue-green algae solution and thus maximize the removal of greenhouse gases. It also aids in increasing the amount of light available to the blue-green algae.

The pipe connected to the gas inlet should come from a height above the bioreactor in the event that the gas flow ceases. When this happens the solution will flow up the inlet pipe until it reaches a height equal to that of the solution in the photobioreactor.

Gas coming in the inlet causes the solution to circulate from bottom to top through the coil without the need of a pump. It also aids in cleaning the tubing due to the scouring action of the gas bubbles rising through the tubing.

The bioreactor is not limited to flue or exhaust gases and may use atmospheric air. In this case air will need to be pumped into the gas inlet.

Copyright Kochn Pty Ltd, January 2006.

O The tubular coil may be made into various shapes depending on materials O available and desired exposure to light. Other than a cylinder, the coil can be a cone, oval cylinder, cuboid, tetrahedron, pyramid or a flat horizontal coil shape.

ct n- The gas should be cooled or heated by a separate system so as to maintain a 0 temperature suitable for the blue-green algae growing in the photobioreactor. For example: a temperature control system which has a gas or water filled coil wrapped around the pipe leading to the gas inlet, and a temperature sensor before Sthe gas inlet to the photobioreactor.

O It is preferred that a tank, rather than a tube be used in the centre of the coil, so 0 o as to increase the volume of the blue-green algae solution in the photobioreactor.

The cone shape coil is preferred to maximize light to the blue-green algae solution.

0 o Refer to the drawings for more detail on the invention.

(N Figure 1 a. shows a side view of the photobioreactor in the vertical coil shape, with a central tube. 1 is the vertical coil of transparent tubing. 2 is the frame that the coil is attached to. 3 is the central tube with 4 being the open end of the tube acting as a gas outlet. 5 is the tap at the base of the central tube. 6 is the gas inlet at the base of the coil angled up into the tubing so that gas bubbles up through the solution in the coil of tubing. 7 is the temperature control system attached to the gas inlet pipe.

Figure 1 b. shows an intersection of the side view of the photobioreactor in the vertical coil shape, with a central tube. Note, the gas inlet going up into the tubing at the base of the coil at location 6.

Figure 1 c. shows the top view of the photobioreactor in the vertical coil shape, with a central tube. Note the gas inlet going up into the tubing at the base of the coil at location 6. 2 is the square shape of the top of the frame.

Figure 2a. shows a side view of the photobioreactor in the vertical coil shape, with a tank in the centre.

Figure 2b. shows an intersection of the side view of the photobioreactor in the vertical coil shape, with a tank in the center. Note, the tubing has been extended into the tank just to highlight the connections to top and base of the coil of tubing.

Figure 2c. shows a top view of the photobioreactor in the vertical coil shape, with a tank in the center. Note the gas inlet going up into the tubing at the base of the coil at location 6. 2 is the square shape of the top of the frame.

Figure 3a. shows a side view of a variation on the photobioreactor in the cone, pyramid or triangle coil shape, with a tube in the center.

Figure 3b. shows a side view of a variation on the photobioreactor in the cone, pyramid or triangle coil shape, with a tank in the center.

Copyright Kochn Pty Ltd, January 2006.