TLDR:

• Cost of algae needed to become economically viable is between 6 to 9 cents for algae weight to make cost competitive biofuel (this is why you need other applications since).

• You need 71,249,232,876,712 kg of algae wet weight to capture all of the world’s co2. This would use 0.478% of the world’s land.

• Everyone in the industry uses raceway ponds (outdoor algae farming) and says indoor algae is “too expensive.” I have chosen to work on decreasing cost of indoor algae farming since it has a lot of advantages yield productivity due it being a closed system. I have identified several cost factors for indoor algae farming: material cost of photobioreactor (used for indoor farming), operational cost of LED lights, operational cost of pumps. In the document I elaborate more on potential ways to decrease cost.

• Identified all of the variables involved in growing of algae and provided my current answers what input is best for each variable.

What Everyone in the Industry is Doing

98%+ commercial microalgal biomass production uses open ponds. From having a few conversation there seems to be the common idea of “Photoreactors [how algae is grown indoors] is too expensive.” People use that logic to discredit indoor algae farming. What they are saying is true, the upfront cost is higher. I have been told photobioreactors are made from high quality plastic to be able to transmit light inside the reactor at high efficiencies.

What is My Claim?

Algae can be a cost-effective method of carbon capture.

What is the Metric I’m Optimizing For?

Cost per kg of wet weight algae and by extension includes cost per kg of dry algae.

At What Cost Will Algae Become Economically Viable?

Algae can be used to make pigments, proteins, cleaning wastewater, carbon capture, biofuel, fertilizer, etc. From the growth of 1 set of algae it seems you can have multiple applications from the same algae. It was mentioned to me the reason why algae biofuel companies failed (in 2010 era) is they only had 1 application of algae, which makes the economics not work. If algae were to work then you would need multiple applications (to make multiple sources of revenue.

Right now the cost that I’m optimizing for is the cost of algae biofuel (which is related to wet and dry weight of algae). As time goes on and I add more applications the cost of algae that I would need to get to will change.

Algae in culture is wet weight. After you harvest algae it is called dry weight. The dry weight is turn into biodiesel (or biofuel). The conversion from wet weight to dry weight is 20-30%, then from dry weight (of algae biomass) to biodiesel is 17.8%. 1kg = 1 liter.

Best case = 0.30 * 0.178 = 5.34% efficiency from wet weight to biofuel. Worst case = 0.2 * 0.178 = 3.56% efficiency

The current cost of petrol in Canada before Ukraine/Russia oil spike was $1.65/liter.

Cost needed for algae Best case = 1.65 / (100/5.34) = 0.0088 or 8.8 cents per kg of wet weight. Worst case = 1.65/ (100/3.56) = 0.058 or 5.8 cents/kg of wet weight. Global Algae (a top X-prize carbon capture team) has decreased cost conventional cost by 6.25x and they are at 0.80kg/dry weight of algae. This means biofuel would cost $4.5/liter (with a conversion of 17.8%), 2.7x more than where they need to be. The above is the reason why you need other applications otherwise you won’t be profitable.

How Much Algae To Capture all of the World’s CO2?

A typical open pond (where you grow algae) can produce 5 to 10 grams of biomass (dry basis) per m2 of surface area per day or 1.8kg to 3.65kg of biomass per year. There are 4046.86m2 per acre. The lowest CO2 biofixation rate from chlorella vulgaris can capture is 1.5g of co2/Liter/day if it is not put a 25% concentration of CO2. The depth of the algae culture is between 10 to 50 cm or 0.1m to 0.5m. With 4046.86 m2 and a depth of 0.1m (worst case) then we would have 404.686m³. 1m³ is 1000 liters. This means you would have 404,686 liters of algae culture per acre (also called wet weight) If we capture 1.5g/liter/day then 1.5 * 404,686 = 607,029g of Co2 per day. 907185g = 1 ton. In 1 day you can capture 0.669 tons of Co2 per acre. In 1 year you can capture 244 tons of Co2 per acre. To capture all of the world’s Co2 (43 billion tons). You would need 176,229,508 acres. 1 Km2 = 247.105 acres which is 712,493 km. The world has 149 million km2. To capture all of the world’s co2 you would need 0.478% of the world’s land.

What I Learned This Week

Big Picture on The Industry

Commercial Algae production has been initiated since 1960s and nobody has figure it out yet. The reason why biofuel companies failed is they only looked at the use case of biofuel from algae. To have good economics you need to have multiple applications to be economically viable. This is made clear by the calculation above on if you only used biofuel as your only application your costs would need to be under 10 cents kg of wet weight algae.

Applications

The common applications I have seen — protein, carbon capture, omega 3 fatty acids, biofuel, cleaning wastewater, bioplastics, pigments, aquaculture feeds, cosmetics, fertilizer.

Depending on the type of application the purity you need changes. If you are cleaning wastewater then your algae purity standard is much lower than if you were to make cosmetic additives

What Everyone in the Industry is Doing

98%+ commercial microalgal biomass production uses open ponds. From having a few conversation there seems to be the common idea of “Photoreactors [how algae is grown indoors] is too expensive.” People use that logic to discredit indoor algae farming. What they are saying is true, the upfront cost is higher. I have been told photobioreactors are made from high quality plastic to be able to transmit light inside the reactor at high efficiencies.

Cost Factors That Need To be Improved

Cost Factor 1: Capital Expedititure of a Photobioreactor

What is unclear to me is why do we need high quality plastics to transmit effectively light and make sure our algae and its nutrients like CO2, Nitrogen, Phosphorus, water do not leave the reactor.

My perspective is your can use a cheaper material to achieve the same outcome. In the worst case you have your have a lower efficiency in light transmission, but your upfront cost goes way down.

Different person mentioned “It was too expensive because you need a lot of material to make small tubes, but at the end of the conversation said “the machines are not that expensive, you can find a cheaper material. Your main cost is actually LEDs, the thing with photobioreactor is you need to prevent biofouling or contamination.”

From another conversion, it was mentioned when considering cost of it depends on the quality of plastic that you have. The higher the quality the more expensive it is. The reason you need high quality plastic is because photobioreactors need to have a pump. The pump helps move around algae cells so they all of them can get adequate light. The pump puts a lot of pressure on the reactor material, so it need to withstand the pressure to be a good material.

If you have bad plastic qualities and sometimes you can make scratches. Sometimes algae or bacteria can be stuck there creating contamination. Contamination kills your yield. If you take glass or other materials you need to be aware of how it reflects light, since it would lower the amount of light that your algae receives.

To generalize, a good material for a photobioreactors needs to be able to let light in your reactor without reflecting it. The material should be able to withstand the pressure from the pump. The material needs be solid enough that you don’t scratch it when cleaning the photobioreactor.

Cost Factor 2: Operation Expenditure of LED Lights

Multiple people I have talked to mentioned your (operational) biggest cost is LED lights. Here are some ways I’m thinking of going around it.

1. You can have the top of your indoor algae farms use glass/plastic/other material that has a high light transmission. This allows you to use the sun as a source of light with LEDs support. This would reduce your cost of electricity from LEDs significantly.

2. You can use solar panels energy to generate electricity during the day. This would some upfront cost, but for the future you have free energy. Depending on season and where you are located you would have somewhere around 8-12 hour (if you discount places like Iceland) of sunlight. If you get enough solar panels to create all of the energy required for LED lights then you can power your LEDs for 8-12 hours a day for free. Plants need somewhere between 12-16 hours of light for optimal growth (and the rest of the time is dark). This can save you 50% to 100% of your cost operational cost using LEDs and you pay the rest with your normal grid provider.

3. You can gene edit the algae reduce the amount of light that the plant needs. Still need to find what specific parts of algae you would edit.

Cost Factor 3: Operational Cost of Pumps

The pumps are what help move around algae culture to make sure all of them have adequate lighting to grow. The pump is operating all of the time (maybe not during dark hours). It was mentioned to me that the pumps are a big cost factor. For optimizing pumps here is what I’m thinking about.

1. You can use solar panels energy to generate electricity during the day. This would some upfront cost, but for the future you have free energy. Depending on season and where you are located you would have somewhere around 8-12 hour (if you discount places like Iceland) of sunlight. If you get enough solar panels to create all of the energy required for pumps, then you can power your pumps for 8-12 hours a day for free. Plants need somewhere between 12-16 hours of light for optimal growth (and the rest of the time is dark). This can save you 50% to 100% of your cost operational cost using pumps and you pay the rest with your normal grid provider.

2. Buy a high efficiency pump. This hypothesis comes from the air conditioning industry. The average efficiency of air conditioners sold today is less than half of what is typically available on the shelves – and one third of best available technology. The reason people don’t buy an efficient air conditioner is because the capital cost is higher than lower efficiently air conditioners, but they don’t take into account the operational expenditure overtime. It is possible a similar problem exists in algae. People in the algae industry are optimizing for the lowest upfront cost when growing algae.

3. Could talk to people that makes pumps and understand those cost factors to make a new pump to decrease cost.

Advantage of photobioreactors (PBRs)

PBRs (indoor operation) advantages over raceway ponds (outdoor operation) include little or no contamination (by other algae, grazers, infections), no water evaporation or CO2 losses, temperature control, higher biomass densities, lower harvesting costs, and higher productivities. The only reason someone would buy a raceway pond because it has a cheaper upfront cost, creating the cheapest cost of algae.

For contamination (which is the reason 1/3 of algae is thrown out), photobioreactors can become contaminated, unless they can be operated as clean-culture, even bacteria-free (axenic) systems. You can only get a clean culture by cleaning the bioreactor after each algae growth, which takes about 14 days from start to finish.

PBRs are generally oriented vertically to dilute the intensity of sunlight received by the cultures and achieve higher productivities by reducing light saturation and photoinhibition. For horizontal closed-packed small-scale tubular PBRs and ponds there was no difference in productivity in side-by-side experiments. This suggests that a good photobioreactor needs to be vertically oriented.

For vertical PBRs versus ponds, limited comparative data shows that increases in productivity are typically less than a factor of two, but the additional PBR area needed to achieve higher productivities is greater than two-fold. Since the costs of PBRs are much larger than the cost of land, this is not cost effective. This means that you need to decrease PBR upfront cost for it to be viable relative to raceway ponds

Photobioreactor Design

One person mentioned they currently use tubular photobioreactors but they will use biofilm (when they scale).

Tubular photobioreactors can transmits light at high efficiencies usually high quality plastic. They have sun at the top of greenhouse and LED light on the side. Which would be a good way to decrease electricity cost of LEDs.

They will use a biofilm which is a mixer that helps all algae cell get exposed to adequate light for growth. The reason for the change from PBRs to biofilm because they want to increase the diameter so you can increase yield for their anaerobic digestion (method of decomposition of sewage or other organic waste). In this case, they are using algae. In anaerobic digestion, the larger your diameter the more yield that you get. They switched to biofilm because if you tried to change the diameter for photobioreactors then you decrease the average light exposure for each individual cell limiting the growth.

Since my use case for algae isn’t as an input to anaerobic digestion, I’m trying to optimize its growth. He mentioned that it is easier to reach max optical density (growth rate), harvest faster, grow algae faster with thin tubes instead of 1 large one.

Another person mentioned that bacteria/contamination is inevitable, what you need to do is constantly check your reactors 2 to 3 times per day to see if there are any signs on contamination. You would do this by using the opening that is used for harvesting and take out a small set of algae to be viewed on the microscope to know if contamination is happening. When algae is contaminated or stressed it is usually stuck together, whereas when they are healthy they are separated. There are 2 types of contamination: bacteria and predator problem. The ph problem requires a change in pH to kill harmful bacteria. If you have a predator problem, it means that a phytoplankton grew which quickly kills your algae.

My thinking is contamination is a very preventable problem (no matter the type), you just need to catch it very early so your algae doesn’t die. You would do this through monitoring sensor that measures if algae cells are getting stuck together or if they are separated. Technology for this likely exists. This is an extrapolation from axiom cold and other cold thermal storage companies, which work with grocery stores and they use sensor to detect any failures in the system. Obviously not the same use case, but similar enough to show it is within the realm of possibility. To be able to test if your system for preventing disease works well you would test in scenarios where algae has a decent probability of death.

Open Raceway Problems

Problem 1: Seasonal Variability

Nature or the current climate has a massive effect on the productivities of raceway ponds. The sun light throughout the year is variable making your yield also variable, since you don’t have another light source. With the increase in greenhouse gases, temperature are reaching more extreme ends causing either too much heat or too little heat. The rain can change the pH of your raceway ponds. Other organisms can get into your raceway ponds causing contamination. These are fundamental problems where you have a limited capacity to change it since you have an open system.

Problem 2: Contamination

A common thing that I have seen as I talk to people when they talk about contamination for open ponds is they commonly brushed over/they don’t expand much on the point. From my understanding, this is the biggest problem with open raceway. I found that 1/3 of algae is thrown away because of contamination. One person mentioned used open raceway with an extremophile (an organism that thrives in extreme environments) like spirulina to prevent contamination. Spirulina reduces contamination because it can grow at high ph (over 10.5+ out of 14), to put it into context normal pH for plants is around 7 to 8. The high pH kills off many organisms that would normally cause contamination. It does not completely negate, but does a decent enough job for the use case raceway ponds, but contamination is still within the realm of possibility.

Different Variables to Optimize

Below are the variables to consider and my current answers for each variable.

1. Indoor vs Outdoor Operation — I am choosing an indoor operation because you can control conditions which increase your yield output for area and you can control contamination in indoor, but not outdoor operations. Contamination is important because it is the reason 1/3 of algae production goes bad.

2. Species + strain of algae — 90%+ of the world’s algae farming uses Spirulina or Chlorella meaning there are more papers/companies that understand how to optimize their growth.

3. Medium — Choosing wastewater. The reason for this is algae is effective at cleaning wastewater so you can get paid for cleaning it and it provides adequate nutrients for algae growth. The incentive for governments to do this is they can get the same standard with cheaper cost (since we will charge them less).

4. Nutrient source (fertilizer) — Comes from wastewater

5. CO2 Source — For an indoor algae operation you can work with manufactures. They have a smoke stack with flue gas. You can can connect the smoke stack and photobioreactor tubes so the flue gas goes in your tubes. Get it from flue gas made by manufactures. The incentive for manufactures in Canada (as of April 1, 2022) is they have a $50/ton carbon tax. For the carbon capture service we can charge them less than the carbon tax and it makes sense for them.

6. Cost of Land — When working with manufacturers to be connected to flue gas you would need to be close to the manufacturing facility. Since the manufacture already owns the land, we don’t have to buy land.

7. Light source — With indoor operations the most expensive operational expenditure is LED lights. The simplest solution is at the top of the building where you hold your photobioreactor you have glass that let’s sunlight through so you can decrease your cost of electricity from LEDs.

8. Temperature — temperature controller, should be relatively cheap

9. pH — Ph controller, should be relatively cheap

10. Mixing machine — Peristaltic pump (don’t have high confidence yet because I have limited info, should be relatively cheap

11. Drying — Gap in my understanding about current process + costs. This is a key driver of algae cost

12. Harvesting— Gap in my understanding about current process + costs. This is a key driver of algae cost

My Current Gaps in Understanding I Need to Figure Out

Need to understand process drying and dewatering of Algae and its key cost drivers.