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Novel algae-based solution for CO2 capture and biomass production

Final Report Summary - ALGADISK (Novel algae-based solution for CO2 capture and biomass production)

Executive Summary:
The ALGADISK project aims to develop a biofilm reactor for algae biomass production which could compete with current algae cultivation technologies (e.g. open-pond and tubular photo-bioreactors). Biofilm formation is a widely observed characteristic of microalgae, which is considered as one of the main problems of tubular, flat-plate and other suspended photobioreactors. While in ALGADISK reactor, biofilm formation is enhanced and supported due to its special design, allowing harvesting high dry solid content biomass, reducing water loss and decreasing energy consumption. The reactor is scalable, modular, contains a sensor and control system to follow and keep growth conditions in optimal range, real time (e.g. pH and volume of medium, nutrient concentrations, temperature). Reactor consists of vertically positioned plastic disks and non-transparent tanks, in which disks are placed half way in growth medium. Surfaces of disks are modified in order to intensify primary biofilm formation and provide sufficient cell number for regrowth of biofilm after harvest. Continuous rotation of disks provides proper wetting of the whole surface and light distribution over the biofilm. In addition, negative effects of saturating light intensity are precluded by cyclic movement of biofilm from light part into the dark tank. Due to the position and orientation of disks, light utilization of reactor can reach a high level, resulting in high biomass productivity. Modules are covered with transparent, removable lids in order to reduce risk of contamination and protect biofilm from extreme weather changes. During the process of system development, concept of CO2 capturing from flue gases was one of the main aspects of design. Reactor is capable of enhancing CO2 to dissolve in the growth medium, just as to reach a high CO2 percentage in the air phase, thus microalgae have access to CO2 both in liquid and gas phase, that results in high biomass production. A semi-automatic harvesting system was developed uniquely for the ALGADISK reactor to provide an easy and efficient method of biomass collection.
In addition to the above mentioned reactor a prediction software application was developed. The main goal of this prediction software is to design and develop a web application that provides the possibility to users to be part of a community based knowledge-base, performs a cost/benefit analysis to calculate economic feasibility and aids the registered user of the predicted environmental sustainability of the system, collect customer information.
The ALGADISK prototype was installed at BFC biogas plant in Almazán, Spain in May 2014. The location provides an optimal environment for biofilm growth by its geographical features. The reactor tanks are installed in east-west direction to let optimal light reach the surface of the disks while at the same time prevent from strong sunlight. After the prototype installation the field test started with bi-weekly harvesting cycles and was running until the end of October 2014.

Project Context and Objectives:
The aim of the ALGADISK project was to develop a modular, scalable and automatic biofilm reactor for algae biomass production, with low operational and installation costs. The reactor was designed on the basis of energy balance and sustainability calculation to capture CO2 from industrial emissions to produce high value organic products. In this system, algae are grown both in an aqueous environment and on biocompatible surfaces, allowing for CO2 absorption from either the gas or the liquid phase. This method dramatically increases the efficiency of the reactor and decreases water requirements. Automatic and continuous harvesting of algae was designed to optimize CO2 uptake and biomass production. ALGADISK has a modular design and the installation’s footprint is considerably reduced compared to technologies currently on the market. Design software is provided which, based on user input, suggests installation parameters, perform cost/benefit analysis to calculate economic feasibility and make predictions concerning the environmental sustainability of the system. The proposed system is specifically crafted to meet the needs of European associations having SME members who are willing to produce algae biomass products from industrial emissions.

The ALGADISK project aims at increasing the competitiveness of members of SME associations and other/end user participants by providing a cost-efficient, innovative and sustainable biofilm based algae production solution with automatic and continuous harvesting system. The SME-AGs and other/end users have put together this project in order to gain knowledge and R&D resources to further exploit the possibilities in algae biomass production with low installation costs and harvesting high dry solid content biomass.

ECONOMIC OBJECTIVES

The economic objectives of the ALGADISK project are:
• To obtain an ALGADISK reactor unit with flexible features that include: 1) opened or closed; 2) additional renewable energy supply and its control; 3) with or without artificial lighting. In addition, development of a design service that will provide for each proposed installation: 1) the optimal alga type; 2) technological operational parameters; and 3) profitability calculations under different scenarios before reactor installation. Users of the ALGADISK system will gain a significant competitive advantage in the field of algae production.
• Construction of one ALGADISK reactor module capable of producing 100 kg of dry algae biomass for under 10.000 €.
• To significantly reduce the cost of algae production, with a 20-85% savings rate as the target. Currently, the cost of algae production varies dramatically. Depending on the type of algae, one kilogram dry biomass costs between 2 and 300 €. For the cheapest, fastest growing algae type, no significant cost reduction is envisioned. However, this project focuses on the more valuable algae types. It is hoped that by using the ALGADISK reactor technology, the average 250 €/kg cost will be reduced to under 50 €/kg.
• To create a new market for Consortium members in the energy supplier market, through development of an innovative technology that can be applied to power plants of every scale.
• To capture CO2 from industrial exhaust, producing valuable organic compounds and biomass in an economically profitable way.

TECHNOLOGICAL OBJECTIVES

The technological objectives of the ALGADISK project are:
• To select microalgae cultures those preferentially grow on surfaces
• To develop lightweight, inexpensive, biocompatible surfaces on which algae grow effectively
• To adapt state of the art PBR reactors to algae growth. This includes the design of adequate measurement and control units (i.e. pH and temperature control) for algae production.
• To develop an automatic harvesting system
• To reduce water requirements for algae growth by using bio-film technology to increase algae concentrations to more than 20 g/l
• To design a reactor capable of installation within one week
• To develop an energetically efficient reactor system through integration of renewable energy sources (wind and solar). The design and construction of an integrated system is planned
• To develop a PC-based tool for users to optimize operational conditions and estimate profitability prior to installation of the ALGADISK reactor system
• To validate and optimize reactor prototypes under realistic conditions

SCIENTIFIC OBJECTIVES

The scientific objectives of the ALGADISK project are:
• To study the biological behaviour of microalgae under partial surface growth conditions.
• To compare CO2 uptake capacity from gas and liquid phases.
• To calculate the energy balance for different alga species.
• To determine reactor engineering parameters (i.e. mixing parameters, mean liquid residence time, relationship between rotation velocity and mixing efficiency, and mass transfer).
• To determine optimal living conditions for different algae species.

TRAINING AND DISSEMINATION OBJECTIVES

The training and dissemination objectives of the ALGADISK project are:
• To develop training activities that facilitates knowledge/technology transfer from RTD performers to Consortium SME-AGs and other partners. Trainings will occur at the pre-validation stage to ensure that partners understand the technology before initiating validation tasks.
• Technology transfer events will be organized to present project results.
• To develop a sound dissemination strategy that includes practical workshops (at least four), conference presentations (at least two), specialized magazines/journal publications (at least three) and mailings (electronic) to at least 500 SMEs.

Project Results:
The Consortium has developed a prototype of modular, scalable and automatic biofilm reactor producing algae biomass with a high degree of quality. The system and the prototype basically consist of the below parts:
• 6 reactor modules including the non-transparent reactor tank, surface coated disk, transparent cover, motor for rotating the disk (the system is modular, number of modules is arbitrary)
• supporting unit
• automatic harvesting system
• control system
• gas cooler
• prediction web-application

A survey on market needs was performed to obtain information necessary for the ALGADISK system specification. Based on the results of the survey the system specification was outlined. In the system specification all parts of the ALGADISK system, i.e. the mechanical design, sensor and control system and the overall requirements were specified according to the needs of SME-AG and other/end-user partners. All major parameters were listed in detail for each step of the technology. The results of the survey have been taken into account during system development.
The algae selection started with isolation of new microalga species from Central Europe and their selection according to a selection scheme. Main criteria were the followings: growth temperature around 35°C; biofilm forming ability; high CO2 uptake rate and high lipid content. Later, the best performing species were used for laboratory pre-test of several surface materials and coatings prepared by CRAN, in order to examine cell attachment to surfaces. The negatively charged outer polyelectrolyte layer enhanced biofilm formation on the surface more than the positive coatings. The selected alga species – Chlorella sp., #34 – was tested in a laboratory scale ALGADISK reactor under its optimal growth conditions. After a 3-month continuous operation period, many advantages of the ALGADISK concept have been revealed such as easy and cost effective harvesting method, high cell concentration of the biofilm (100-150 g/l), continuous operation and several growth-harvest cycles could be achieved without reinoculation of the system. In the further experiments light has appeared to be less limiting, than CO2, while different medium had significant effect on biomass production. Lipid content of biomass slightly increased due to stress factors. Besides disk coatings, the disk material was also examined for cell attachment. Conclusion could be drawn that disk substrate had little influence on the biofilm production.
The strategy of using polyelectrolyte coatings to attract algae onto the surface was developed. After extensive testing, coatings and surfaces were further optimised and characterised. A final coating was selected to be used with the algae selected in the prototype. The traditional method for polyelectrolyte application was changed to a newly developed airbrushed method. This was to better suit large scale applications and was used to coat disks for the prototype.
The design of the developed reactor system was carried out between M3 and M25 and included the conceptual design, sensor and control system design, harvesting unit and supporting system designs and reactor model studies. The outcome of this work is a complete technical documentation of the system which was shared with the consortium partners and presented in the relevant deliverables. A laboratory scale ALGADISK test system was constructed to test and finalize the control setup developed and also to have the opportunity to make harvesting trials. The control system and control loops realized in the laboratory scale system are identical to the pilot-scale system, modifications on the actuators and sensors could occur due to the different size and working method of the systems. The pH, media level, media conductivity, media temperature, input gas temperature and disk rotation need to be controlled, other parameters such as media dissolved oxygen, insolation are monitored only. The constructed control system is simple, stable, modular and easily adaptable to fulfil the needs of an outdoor industrial marketable ALGADISK system.
The prototype construction was carried out completely in the second reporting period. The reactor system was manufactured and laboratory tested before the installation. The auxiliary equipment unit was manufactured and tested. Exact types of the above sensors depended on the mechanical design and were determined to fit the mechanical construction. The sensors for the pilot reactor were selected and acquired. The final PLC setup was selected, integrated into the control cabinet. The control software was developed to enable on site and remote controlling of the system as well. The whole control system was integrated with the mechanics and pretested before transportation to end user facilities where the performance test was carried out. After the laboratory test the whole system was transported to its final destination which is BFC biogas plant, Almazán, Spain. At the site the reactor system, the supporting auxiliary unit and control system was integrated and the system was installed, connected to the plant infrastructure and tested. All upcoming challenges were solved, for example the foam level transmitter interfered with the conductivity sensor, thus it was disconnected and the system was set to manual anti foam addition. The control electronics performed well during the test period except the pH sensor. Since the pH sensor had manufacturing error, it was replaced in warranty process and then also performed as expected.
The prediction software development started with a throughout data collection process where the necessary data (algae type, hardware costs, prediction parameters) were identified that formed the base of the whole prediction module. The first version of this module was developed in MATLAB, while the final web application contained the final (PHP-based) version of this module which is able to estimate the biomass productivity as a function of location. Based on this productivity the requirement of specific nutrients (fertilizers) can also be calculated. However, it is important to note that this developed prototype is focusing only on Chlorella sorokiniana algae type. The (alpha and beta) testing period successfully proved that the developed modules work as they were designed and the developed user-friendly user interface gives the user great possibility to be a part of an “algae” community finding and sharing information among other members of the ALGADISK community on the website increasing the algae biomass productivity, quality of the ALGADISK users.

The biological part of the ALGADISK system appeared to be very robust during the outdoor field test. After all challenges encountered, issues were solved and ALGADISK always could be restarted quickly without re-inoculating the disks. The disks could always be quickly re-populated with Chlorella. However, these technical issues have negatively influenced the productivity during the field test. The second harvest cycle was the most productive with 12 g/m2/d (normalized to ground surface) although the CO2 supply was still limiting because the CHP unit was not running continuously throughout the day. Nevertheless, the field test clearly showed that the microalgae biofilm was growing rapidly when flue gas was available and the flue gas appeared to be a good source of carbon dioxide and no side effects of its utilization were observed.
We have good reasons to expect that much higher productivities are feasible in the ALGADISK system when any CO2 limitation is removed. With the prediction software it can be shown that the productivity can be increased to maximally 35 g/m2/d (= Pground). Although the ALGADISK project officially ended in December 2014, ALGADISK partner BFC will still adapt the current prototype. As suggested in the discussion, a back-up CO2 supply will be installed in order to prevent CO2 limitation at any time. The prototype will thus remain at the BFC plant in Almazan, Spain and will be tested again in the spring of 2015. The aim of this final test is to assess the maximal productivity of the ALGADISK under ideal (non-limiting) conditions and confirm our model predictions.
All controllers of the ALGADISK were functioning properly minimizing the amount of labour to keep the ALGADISK running. Temperature could be maintained below a maximal threshold of 35ºC. Provided there was flue gas, also the pH could be maintained and dissolved oxygen concentration remained below 10 ppm. The conductivity measurement demonstrated to be very useful to monitor and control the correct dosing of fresh nutrients. The regular antifoam addition showed to be robust and prevent any excessive foaming. The only unexpected behaviour was related to a drop in pH probably due to decay of accumulated biomass in the tanks. This problem was solved by manual addition of sodium carbonate and in the future its automatic addiction can be easily implemented in the reactor controller.
From the material side the outdoor experiments showed that the design of the disk and its material choice have to be adapted to prevent bending of the disks itself as well as the tanks holding the liquid through which the disk rotate. Technical solutions for these issues have been identified and were reported in the deliverable 9.4 (Final Plan for the Use and Dissemination of Foreground).
The automatic positioning system to harvest the disks appeared to run without any problems at the end of the field test. The biomass concentration harvested was 89 g/L in the most productive cycle (cycle 2). It is expected that the biomass concentration will be higher than this when the productivity is enhanced by removing the CO2 limitation. This will result in thicker biofilms leading to a relative decrease of the amount of water collected during the harvest. Based on laboratory experience a biomass concentration over 100 g/L must be the minimal possible.
During the project meetings the RTDPs shared the result with the SME-AGs and other/end users by facilitating the take-up of the knowledge gained among the SME-AGs and other/end users. ATEKNEA was giving presentations on the mechanical parts and operation, control system, usage of the control panel and prediction web-application, speeches of BAYBIO were on the algae selection, laboratory experiments, optimal conditions of algae surface attachment growth and operation of the laboratory scale ALGADISK reactor, CRAN presented on the surface coating of the disks, while WU gave trainings on dimensioning the supporting energy system and accessories, gas cooler unit, microalgae both in general (growth, nutrient requirements, productivity) and in ALGADISK, state-of-the art suspension cultures, photobiobioreactors and current trends in algal biotechnology. The trainings were backed up not only by PowerPoint presentations but also with videos and live prototype demonstration to ease the take up of the knowledge.
The ALGADISK website was set up successfully at the beginning of the project. It contains a public part with major information of the project as well as a restricted area for consortium members with the possibility of up- and download documents and viewing restricted information. The website has been updated at every important project related event and important news but at least in every three months. The address of the website: www.algadisk.eu.
The consortium management actions took place as planned: after establishing the channels necessary, communication has been running smoothly led by the project coordinator with the active involvement of consortium members. General project meetings have been organized on a six month basis, while technical meetings have been held every 3 months. Beside the meetings, some mutual partner visits took place and Skype discussions were organized. Continuous update and communication have been done on a regular basis towards the Project Officers.
During the M36 final general meeting held on 9-11 December 2014 in Budapest, Hungary the consortium reviewed and discussed the project status as well as the performance and results. SME-AG and other/end user partners were very satisfied with the work of RTD partners, since the associated results were achieved, during the meeting evidences were presented and at the M33 general meeting a live prototype demonstration underlined the fully functional ALGADISK system.

As a summary, the main results achieved are as follows:
• All necessary laboratory experiments and trials were completed
• The best algae species were selected according to the selection scheme (main criteria were: growth temperature around 35°C; biofilm forming ability; high CO2 uptake rate and high lipid content)
• The algae surface growth condition has been optimized
• The surface coating was selected, tested and further developed (airbrush method)
• The ALGADISK system was fully designed with the assistance of SME-AG and other/end user partners reflecting the content of the system specification
• All parts of the ALGADISK system constructed and successfully integrated
• The system was tested and validated at the installation site (BFC biogas plant in Almazan, Spain)
• Sample analysis and evaluation of field test results was performed
• Prediction web application has been developed including economic model and algae community features

Potential Impact:
The use of microalgae biomass for human nutrition is the best established and most important market of microalgae biotechnology based on quantity of produced biomass and sales turnover. The use of microalgal biomass as animal feed represents the second largest area of application. Up to 30% of the current algal production globally is sold and used as a supplement for feeding different animals such as fish in aquaculture, pets and farm animals. More than 50% of the Spirulina produced is used for this purpose. The addition of 5–10% of algal biomass to the feed has a positive effect on the physiology of the animals, mostly because of the high content of vitamins, minerals and essential fatty acids. The algae enhance the animals’ immune system and fertility, and produce healthy skin and a shiny coat. On the other hand, the biomass is used as an additive to fish feed, which improves the colouring of farmed salmons and the induction of important biological processes such as enhanced growth, resistance against diseases, firmer flesh, better flavour and brighter skin. Fish flesh becomes healthier and tastier, due to the high protein and unsaturated fatty acids content provided by microalgal biomass. Nevertheless, the fish demand for human nutrition is growing, and the actual prices for fish oil and meal are increasing due to the increasing scarcity of natural fish resources. These facts give a positive impetus for the application of microalgae biotechnology for aquaculture. The high value food additives and ingredients, for example DHA, that are made from algae have a growing market. For example, 99 % of all baby food in the USA has the algae-derived DHA ingredient is produced. Other large food ingredient producer companies such as BASF, Unilever and Dow Chemical, have realized the potential of the food ingredients market and its impressive growth and have made massive investments. Despite these benefits low European demand and complex regulation of novel foods and inadequate climate for widespread production of micro-algae at a competitive price restrain European firms.

Biomass, as unique existing renewable carbon-based source, plays a crucial role not only in the renewable energy sector but also in carbon capture, GHG emission reduction and increased sustainability for the transport sector. The agriculture sector produced 461 567 kilo tonnes of CO2 equivalent greenhouse gases in 2010, around 10% of the total EU emissions (excluding Land Use, Land Use Change and Forestry (LULUCF) net removals) for that year. Emissions from the agricultural sector have declined by 22 % since 1990. Reduced nitrous oxide emissions from agricultural soils, (now 49% of total agricultural emissions in EU) that decreased by 23 % mainly due to a decline in the use of nitrogenous fertilisers, now no more applicable. Reduced methane enteric fermentation emissions (now 32% of total agricultural emissions) that decreased by 22 %, due to an overall reduction in livestock numbers i.e. cattle and sheep. The application of synthetic fertilizers has a high impact in terms of CO2 emission. In 2012 the fertilizer production industry generated about 300 million tons of CO2 on world scale. Biofertilizers industry can become a new promising sector where biobased feedstock will be able to replace the fossil based Nitrogen sources and reduce the emissions related to their utilization. Many technologies have been identified and studied during the last years. Here comes the large interest on algae biomass as feedstock for valuable fertilizer production, able to increase the soil quality, reduce the emissions and improve the biomass growth yield in different climate conditions. Many studies proved that the integration of microalgae biomass (i.e. spirulina etc.) in biofertilizer for cereal cultivation provide valuable benefits. The cultivation of algae in European Farms (also small scale) for biofertilizer production (and high quality food) is getting of great interest for investors, land owners and algae producers.

ALGADISK is a biofilm reactor for algae biomass production which could compete with current algae cultivation technologies (e.g. open-pond and tubular photo-bioreactors). Biofilm formation is a widely observed characteristic of microalgae, which is considered as one of the main problems of tubular, flat-plate and other suspended photobioreactors. While in ALGADISK reactor, biofilm formation is enhanced and supported due to its special design, allowing harvesting high dry solid content biomass, reducing water loss and decreasing energy consumption. The reactor is scalable, modular, contains a sensor and control system to follow and keep growth conditions in optimal range, real time. The reactor consists of vertically positioned plastic disks and non-transparent tanks, in which disks are placed half way in growth medium. Surfaces of disks are modified in order to intensify primary biofilm formation and provide sufficient cell number for regrowth of biofilm after harvest. Continuous rotation of disks provides proper wetting of the whole surface and light distribution over the biofilm. In addition, negative effects of saturating light intensity are precluded by cyclic movement of biofilm from light part into the dark tank. Due to the position and orientation of disks, light utilization of reactor can reach a high level, resulting in high biomass productivity. Modules are covered with transparent, removable lids in order to reduce risk of contamination and protect biofilm from extreme weather changes. During the process of system development, concept of CO2 capturing from flue gases was one of the main aspects of design. Reactor is capable of enhancing CO2 to dissolve in the growth medium, just as to reach a high CO2 percentage in the air phase, thus microalgae have access to CO2 both in liquid and gas phase, that results in high biomass production. A semi-automatic harvesting system was developed uniquely for the ALGADISK reactor to provide an easy and efficient method of biomass collection.

The expected results are achieved and extended with further sub-results which were not planned at the beginning of the project. The prototype remains at BFC. The laboratory scale reactor gave additional results to the listed ones and at the final meeting SME-AG and Other/End user partners decided which partner will keep the laboratory scale reactor for investigation purposes and further optimisation:
-2 laboratory scale reactors: BAYBIO will keep it.
-Simplified version of laboratory scale reactor: Swedish Algae Factory keeps it

From market point of view, the whole mechanical system, including the six units, the control system and access to the prediction application are regarded as the product. As the system is modular, number of modules can be selected by the customer. The control system is capable to control up to 10 units, so in case of more units, an additional control system is needed. The set-up of the system needs special experience, thus it will be provided as part of the ALGADISK product package. The ALGADISK reactor is not recommended to operate in cold weather conditions, thus the reactor should be stopped for winter season.

There are several key features of ALGADISK: which could lead the product to a competitive edge:
-High biomass density of harvested biomass / High product concentration
-Automatic controlling and sensor system
-Controlled parameters, reduced risk of contamination
-Easy and efficient harvesting
-Excellent and simple control of process conditions
-Resulting in high biofilm growth rate
-Simple harvesting
-Possibility to use flue gas and wastewater streams
-Scalability of the system, target of easy maintenance, low footprint
-Low labour input

However, market readiness is a crucial aspect of exploitation planning and time-to-market. It is agreed by the consortium members that the pre-competitive prototype must be further developed before entering into the market. The technical development will be mainly focused on different issues to get a final marketable system:
-High systems cost leading to high cost of biomass
-Problems of long-term operation
-Limitations of the application of the system: slowly growing microalgae production for high value products

Based on the above considerations consortium partners have decided to follow two separate exploitation paths:
-Price optimized ALGADISK approach
-New technology biofilm cultivation

New technology biofilm cultivation includes completely abandoning the disk concept and replacing it with a more area efficient geometry, like belt, flat-bed and transparent tube. These approaches do build up on knowledge and experience obtained in the ALGADISK project, mainly in the area of surface preparation and harvesting technology, but otherwise represent a number of novel challenges. It might require significant R&D investment of be in the scope of future EU projects for which the consortium already identified several possibilities both open calls and new concepts instead of the disk technology. The consortium is confident that with applying the knowledge gained from ALGADISK project can support the further developments.

The price optimized exploitation path will use essentially the same concept as used in the ALGADISK demo, but optimized and improved to reach (marginal) economical breakeven. Improvements include among others:
-Improved and reduced housing to improve ratio between materials cost and productive area,
-Validation with different alga types,
-Improved disk material (for cost, rigidity and thermal stability),
-Stabilized CO2 source (complemented by stored CO2 to bridge shortage of flue-gas supply due to maintenance and other reasons),
-Cost reduction of units by reducing material requirement and water volume,
-Increased unit size, allowing scale-up,
-Further automatization and scale-up of harvesting unit,
-Robust year-long operation

In order to be able to further develop the ALGADISK system with a cost effective approach, the partners mapped the possibilities of getting additional funding too.

OTEC and UTECH would provide the mechanical system of the reactor while ALGEN the control system. The distributor of the ALGADISK reactor would be CAGLAR. SME-AG members of the consortium will support the marketing actions of the distributors. Furthermore, EUBIA will host the prediction software application. This website will provide the base of early marketing actions besides the dissemination activities of SME-AGs.

The consortium already implemented several dissemination actions during the project which gave a stable base for future marketing activities. The main actions focused on printed materials, online materials and personal dissemination. The printed materials such as leaflet, poster, newsletter, supported the conference visits, workshops while online dissemination also received great attention. A project website and project video were designed. Several online news and articles were published.

List of Websites:

http://algadisk.eu/