GB2473865A

GB2473865A - Cultivation system for algae employing tubes

Info

Publication number: GB2473865A
Application number: GB0916957A
Authority: GB
Inventors: Gary Tulie
Original assignee: ALGOIL Ltd
Current assignee: ALGOIL Ltd
Priority date: 2009-09-28
Filing date: 2009-09-28
Publication date: 2011-03-30
Also published as: GB0916957D0

Abstract

A cultivation system for micro-algae comprises of closed bioreactors 2 made by heat sealing together two sheets of plastic to create a flat tube with an entry 1 and exit 4 pipe allowing circulation 3 of algal culture. Each bioreactor may comprise a plurality of tubes. A plurality of bioreactors may be connected together by means of springs, elastic rope, dampers 5 etc. The algal culture flows through the system and then maybe transferred to a settlement / filtration system where continuous harvesting may take place. The system may be utilised by floating on a body of water such as lakes or seas or may be used on reasonably level ground. The system may be rolled up for manual deployment on land or mechanical deployment by boat.

Description

INTELLECTUAL

. ... PROPERTY OFFICE Application No. GBO9 16957.4 RTM Date:15 December 2010 The following terms are registered trademarks and should be read as such wherever they occur in this document: Jubilee Intellectual Property Office is an operating name of the Patent Office www.ipo.gov.uk Floagal -Floating Algal Cultivation System

Introduction

In recent years, cultivation of algae has received an increasing amount of attention.

Algae have a number of interesting properties, in particular potential for very fast growth, and for some strains, a high oil content which can exceed 50%.

Algae vary enormously in size from single celled plants to seaweeds many meters in length, and altogether comprise over 90,000 species most of which are found in salt water. As well as a high oil content which could potentially be utilised as fuel, algae have wide potential in human and animal nutriceuticals, as a source of food colourings, pharmaceuticals, fish food, water retaining gels to enhance desert agriculture, fertiliser, cosmetic applications and for many other applications.

Naturally occurring fossil fuel oil is derived from a range of carbon rich sources including prehistoric algae, particularly of the diatom group. Production of bio-diesel using the same feedstock is therefore a practical application.

Given their potential for biofuels, most attention has recently been focused on the cultivation and use of single celled algae. Whilst cultivation systems based entirely on biofuel production presently have difficulty in being cost effective, processes which exploits algae to produce a range of high value fine chemicals prior to preparation of bio-diesel from the residual oils are close to commercial viability.

Cultivation systems are generally divided into open pond and closed bioreactor types, with the former less costly but less controlled and productive than the latter. In both types of system, algae are circulated aerated and agitated sufficiently to keep them in suspension and so to avoid poisoning the culture with by products of algal metabolism. Agitation and circulation use a significant amount of energy, so that a substantial proportion of the Carbon Dioxide biologically sequestered by algae gets released producing the energy to run the system. Floagal is designed as a very low cost but potentially high performance closed bioreactor system able to float on a body of water, or capable of use on suitably prepared level ground.

This patent relates to the cultivation of single celled algae in closed floating bioreactors designed for easy fabrication, low cost, and at large areas of deployment.

Overview Floagal is designed as a very low cost and simple algal cultivation system designed primarily for deployment on a body of water. In essence, the Flogal is made up of two sheets of plastic joined together by heat seals to form a continuous reciprocating flat tube with an appearance much like an inflatable mattress or Lillo. The lower of the two sheets may be alurninised to reflect light back up through the culture, whilst it is important that the upper sheet contain a UV filter in order to both protect the Floagal extending its life, and protect the algae from UV damage / growth inhibition. The Flogal has an inlet and an outlet pipe and is designed for continual cultivation and harvest. Many units can be joined together in parallel to give as large a cultivated area as desired. In order to hold the units together, they may be connected by bungee cord, hydraulic / induction dampers or similar giving a degree of flexibility whilst retaining the overall special relationship between Floagal units. If hydraulic or induction dampers are used, power may be generated by the stretching and compression of the same as the units float together or apart under the influence of waves. The units are designed for very low cost manufacture and deployment in order to allow cost effective cultivation so enabling cost effective algal biofuel production with simultaneous production of many other higher value products such as vitamins, minerals, protein, omega 3 -6 oils (unsaturated fatty acids) for food use such as margarine, cosmetics, food colourings and various other fine chemicals.

When manufactured, each Floagal is rolled up for easy and low cost transport, and needs only to be unrolled and connected onto circulation pipes and using bungee cord to other units in order to join a farm of similar devices. Deployment is therefore simple, either manually on land, or by unrolling from the back of a boat onto water.

The device is then connected onto pipes using jubilee clips or similar, so connecting it to the farm circulation system. Each connection contains a valve which can be manually closed permitting each individual Floagal to be disconnected for maintenance or replacement without disrupting the rest of the farm. For deployment on a body of water, several units can be assembled on land adjacent to the body of water, attached together and to the inlet and outlet pipe system, then carried into the water.

As an alternative to floating on water, the Floagal can be placed on level or slightly sloping ground. In this case, provision is made to damp thermal cycling by passing the culture liquid through a heat exchanger at each pass through the settlement tank / filtration system. In this way, the system is prevented from reaching excessively high temperatures such as would inhibit the algae, and temperature is not allowed to decline too much overnight. The heat so extracted can find a number of uses such as evaporating sea water for desalination, or pre-heat for water heating.

For cool climate cultivation, the Floagal can be constructed in insulated form with a bubble sandwich type construction -clear in the upper sheet, and with multiple aluminised layers in the lower. Such a construction may be suited to sunny but cool areas such as plateaux regions of Central Asia.

The system is designed to allow supplementary aeration / addition of C02 and nutrients each time the culture passes through the filtration system, which in the case of multiple relatively small units might be as frequently as every 30 minutes.

For larger units with a longer cycle time, additional measures to pump air through the Floagal can be undertaken. This will most easily occur where the Floagal is installed on a slight slope, with air or C02 injected at the lowest point, and flowing uphill contrary to the flow of the liquid.

When deployed on land in arid or semi arid zones, the Floagal may be slightly modified to optimise collection of any rain falling on it. Floagal forms relatively large surfaces, often on slight slopes. By catching rain water running off the Floagal in a gutter and directing it into tanks or reservoirs, said rainwater can be made available for other uses such as drinking and irrigation.

As the Floagal will inevitably become contaminated with a bioflim of algae or Cyanobacteria, measures are taken to build in a non-stick surface to minimise this bioflim. The liquid in the Floagal is also kept constantly flowing to minimise settlement. Once levels of contamination become unacceptable for algae farming, the unit may be detached from the algae oil cultivation system, and attached to a secondary circulating system for a cleaning cycle. In this cycle, fish or shellfish are introduced to the Floagal to eat the algal biofilm. Such fish may be utilised for food, or may possibly find higher value markets producing specialist fish for the aquarium market. Depending on the condition of the unit, it may once clean be put back to the cultivation of fuel algae, or remain in the fish farm section until retired.

When a collection of Floagal units are used to cover the majority of an agricultural or other reservoir, this covering effect will substantially reduce evaporation. (Some aeration below the Floagal units might be indicated). In this way, the amount of water provided for irrigation, or available for hydropower production may in some cases be substantially increased. Such floating Floagal units might also be used as a filter to remove excess nitrates, phosphates, and other nutrients from contaminated farm runoff or the outflow of sewage treatment works, so improving water quality. In such use, and subject to removal of the cultivated algae, the water quality of water exiting the Floagal will be much purer than that entering, so making it fit to flow into sensitive rivers, estuaries etc. without causing eutrophication. This is particularly useful where coral reefs are found near estuaries.

Labels Figure 1 & 2 1. Feeder pipe supplying water and inoculum to algal cultivation system (Floagal) 2. Plan of Floagal unit showing the construction of tubes using heat seals or adhesive 3. Flow direction 4. Exit pipe taking culture to filtration system 5. Stretchy cormectors keeping the special relationship between Floagal units broadly constant.

6. Heat seal or glue used to make reciprocating pipe 7. Airspace 8. Algal culture

Claims

Claims 1. Floagal is made up of sheets of plastic film heat sealed or glued together for easy low cost manufacture.
2. Floagal uses reciprocating parallel tubes formed by heat sealing together two plastic films along most of the length of said sheet.
3. Floagal uses heat sealing to form a sealed perimeter with inlet and outlet tubes for connection to a circulation system.
4. Many Floagal systems can be assembled together into a Floagal farm for the cultivation of Algae and Cyanobacteria, and for concurrent farming of fish or shellfish (Fed on the algae).
5. The Floagal system incorporates a UV filter to protect both itself and the culture.
6. The Floagal system incorporates a reflective film on its lower surface to reflect light back up through the culture and to help retain heat.
7. The Floagal system incorporates valves between the two Floagal ports and the culture circulating pipes, so enabling removal and replacement of a unit without disrupting the whole system.
8. When used on water, the Floagal system has a high thermal conductivity bottom layer allowing the contents to be cooled by conduction of heat into the water below.
9. The Floagal uses feeder pipes to deliver water to and remove it from multiple Floagal units, so delivering economies of scale.
10. The Floagal feeder pipes allow algae to be delivered to land, to a settlement tank, or a floating processing unit for concentration and processing to a range of algal products.
ii. Floagal uses springs, elastic rope, hydraulic dampers or other mechanisms of similar effect to keep floating units in correct special relationship with each other whilst allowing a degree of flexibility to reduce stress on the materials.
12. The Floagal may be built out of "bubble sandwich" materials similar to bubble wrap, the lower of which uses multiple aluminised layers for insulation.
13. When built as in 12, Floagal forms a solar heating panel, warming its contents to boost growth rate, and allowing heat to be extracted such as to preheat district heating water.
14. The Floagal is designed to optimise growth of Algae and Cyanobacteria.
15. The Floagal provides a protected facility in which to farm fish utilising algae as their feed.
16. Using dampers containing induction coils, wave energy may be harnessed to mnn the pumps etc by which the system operates.Amendments to the claims have been filed as follows: 1. A device for the cultivation of micro-algae, fish farming, water purification and solar heat capture that consists of two plastic films sealed together to form tubes through which a culture of micro-algae is circulated and aerated.2. The device according to claim 1 whereby the upper plastic film contains a UV filter.3. The device according to claim 1 where the lower plastic film contains an aluminised reflective surface.4. The device according to all the claims above whereby the plastic films are heat sealed or glued together in a reciprocating design of parallel tubes resembling an air mattress through which the culture of micro-algae is circulated.5. As in claim 4, sealing together plastic films to form a sealed perimeter with inlet and outlet tubes for connection to a circulation system.6. Assembly of a number of the devices in claim 1 together to form a farm for the cultivation of algae and cyanobacteria and for concurrent farming of fish or shellfish, fed on the algae.7. The assembled collection of devices as in claim 6 interconnected with settlement / filtration systems for the harvesting of algae.8. The assembled collection of devices as in claims 6 and 7 with valves between the ports of units and the culture circulating pipes to enable removal and replacement of a single unit without disrupting the whole system.9. As in claim 8, use of manifold and feeder pipes to deliver water to and remove water from multiple units of the device. 10. As in claim 9, the feeder pipes that transfer algae to a settlement tank or filtration system for concentration of algal.Q 11. The device in claim 1 constructed from "bubble sandwich" materials similar to J bubble wrap, the lower of which uses multiple aluminised layers for insulation.12. The device in claim 1 that acts as a solar heating panel, warming its contents to boost growth rate and allowing heat to be extracted.13. The device in claim 1 as a fish farming facility with the fish utilising algae as their feed and providing a cleaning service to each unit which has developed a significant algal biofllm.14. The feeder pipes according to claims 9 and 10 that allow algae to be delivered to land, to a settlement tank, or a floating processing unit for concentration and processing to a range of algal products.15. The device in claim 6 that uses springs, elastic rope, hydraulic dampers or other mechanisms of similar effect to keep floating units in correct special relationship with each other whilst allowing a degree of flexibility to reduce stress on the materials.16. Using dampers according to claim 15 that contain induction coils to harness wave energy to run the pumps etc by which the system operates.