SPIRULINA SYMBIOSIS
INTRODUCTION I. WHY SPIRULINA ? II. THEORITICAL SPIRULINA FARM FOR 1-2 PEOPLE FOOD SELFSUFICIENCY CONCLUSION
INTRODUCTION We all want freedom. What is being free ?_ Being free means not depending on something else._ Is it possible ? I don’t think so._ True freedom is unlimited resources and being able to satisfy any desire. On a limited environment or even universe, ruled by physic and moral laws true freedom is therefore imposible to reach. I also think that not being free is part of our human condition. However, in my opinion, we can get closer to freedom compare to what we are experiencing in the modern civilization. There are many different ways of scraping bits of freedom. One would be to go back to a primitive way of life and another one would be to develop sustainable living without loosing confort and keeping devolping our technique, love and wisdom. The last option is what I’m focusing on. Here is a list of selfsuficiency basic needs, with some ideas to reach them:
1.Food _spirulina _lemon _other vegetables depending on the season and area (can be grown inside and outside of an hydroponic greenhouse) _goat (milk and cheese) _chicken _fishes from fishing 2.Home _Module 1 - House _Module 2 - Workshop _Module 3 - Greenhouse (hydroponic system + fish pond to make the water rich in nutrient) _Module 4 - Spirulina (connected to green house) _A dome made of soil to insulate even better _Insulation panels made of mycelium 3.Energy _Solar panels on a dome or flat surface (about 2000W) 4.Health _Medicinal plant cultivated in the green house and outside. list of antibiotic recipe _Basic chemicals stock 5.Knowledge _The internet _Book Bank _Music Bank _Movie bank _CAD Bank
6.Tools _A workshop (fablab) _Basic tools for as much thing as possible _3D printers _Laser Cutter _Sewing machines _Welding _Material stock _Manufacturing should be standardized 7.Mobility _Bicycle _Truck??? _Sailing boat _Ultra Light Aircraft 8.Social Connections: _Internet _Proximity with people ???
For this work, I’ll turn my interest towards food selfsuficiency. By taking spirulina as the main componenent of a diet, I’ll develop a theoritical spirulina farm that is able to supply on a daily basis almost all the nutrient needed by 1-2 human bodies. My goal is to make this farm as much automated as possible and to make it the size of a small 20 feet container.
I. WHY SPIRULINA ?
1. What is spirulina Spirulina is a small living being (length = 0.3 mm long), as old as earth. Its scientific name is “Cyanobacteria Arthrospira Platensis” (can be mistaken for marine cyanobacteria called “Spirulina Subsalsa”), it lives from photosynthesis like plants and thrive naturally in salty and alkaline lakes in warm areas of the globe. Traditional food of Aztecs in Mexico and Kanembous in Tchad, richer in protein than meat, spirulina is now grown in big factories in USA, India, China, Thailand, etc. We always find new interesting qualities for nutrition and health benefiting humans and animals. For example, a child suffering from malnourishment can be healed by eating a tea spoon of spirulina every day for a month. It can also strengthen immune defense and reduce the pain for AIDS sufferers. It can also help people with tuberculosis to better support their treatment. Spirulina is also used as an active ingredient in cosmetics. In nature, the only need of spirulina for growing is an argillic pond filled with brackish and alkaline water, under a warm climate, and some animal defecations. Pink flamingos bring enough dejections and agitation to guarantee the growth of natural spirulina, especially in Est African’s lakes (Rift Valley). Spirulina takes the form of filaments constituted by juxtaposed cells. Its asexual reproduction is made by filaments division.
2. Spirulina composition and daily quantity of nutrient for an adult human Comparison side by side between recommended daily intake (minimum) of a 175 cm 70 kg male human and 100 grams of dry spirulina. There is around 380 kcal for 100 g of dry spirulina.
Nutrients Recommended daily intake Quantity for 100 g of dry spirulina Proteins 50 g 65 g Alanine 0.500 – 2.000 g 4.7 g Arginine 2.000 g 4.3 g Aspartic acid 0.500 – 2.000 g 6.1 g Glutamic Acid 5.000 – 10.000 g 9.1 g Glycine 0.500 – 2.000 g 3.2 g Histidine (Essential) 0.700 g 1.0 g Isoleucine (Essential) 1.400 g 3.5 g Leucine (Essential) 2.730 g 5.4 g Lysine (Essential) 2.100 g 2.9 g Methionine 1.050g 1.4 g + Cystine (Essential) + 0.6 g Phenylalanine 1.750 g 2.8 g + Tyrosine (Essential) + 3.0 g Proline 0.500 – 4.000 g 2.7 g Serine 0.500 – 3.000 g 3.2 g Threonine (Essential) 1.050 g 3.2 g Tryptophan (Essential) 0.280 g 0.9 g
Nutrients Recommended daily intake Quantity for 100 g of dry spirulina Threonine (Essential) 1.050 g 3.2 g Tryptophan (Essential) 0.280 g 0.9 g Valine (Essential) 1.960 g 4.0 g Carbohydrates (sugar) 260 g 15 g Minerals (total) -- 7 g Chrome 4 µg 300 µg Calcium 800 mg 1000 mg Copper 1 mg 1.2 mg Iron 14 mg 150 mg Magnesium 375 mg 300 mg Manganese 2 mg 3.0 mg Phosphorus 700 mg 800 mg Potassium 2000 mg 1400 mg Sodium 1 500 mg 400 mg Zinc 10 mg 3.0 mg Iodine 150 µg 0 – 1.7 mg Selenium 55 µg 5 – 10 µg
Nutrients Recommended daily intake Quantity for 100 g of dry spirulina Lipids (fat) 70 g 6 g Linoleic acid (Omega-6) -- 0.8 g Gamma-linolenic acid (GLA) (Omega-6) -- 1.0 g Fiber 30 g 4 g Water -- 5 g Vitamins A (Beta-carotene 800 µg 140000 µg C 80 mg 10.1 mg E 12 mg 10 mg B1 1.1 mg 3.5 mg B2 1.4 mg 4.0 mg B3 16 mg 14 mg B5 6 mg 0.1 mg B8 or H 50 µg 5 µg B12 2.5 µg 320 µg (maybe not entirely assimilated) K 75 µg 2000 µg
II. THEORITICAL SPIRULINA FARM FOR 1-2 PEOPLE FOOD SELFSUFICIENCY
My idea is to design and engineer a viable medium sized, automated spirulina farm model producing enough food to supplant almost all of the nutrient daily intakes of 1-2 adult human. This project could be a module part of whole modular living space system. The total ponds size should be 20m² to produce 140 g/day of spirulina. A 75 kg/175cm male adult needs minimum 50 g/day of protein. 1. Enclosure and ponds We know that we can produce 7 g/day/m². We’ve also know that a male adult needs a minimum of 50 g/day of protein and that 100 g of spirulina contains around 65 g of protein. With a quick calculation we can find what should be the size of a pond to get a bit more protein than the minimum for a human, 65 g of protein : (100(g) × 1(m²))/(7(g))= 14.285 (m²). However, because 14 m² is impractical to work with and because the production of the culture could be less than expected, we will focus on a surface of 20 m². Thus, with another calculation we find that we can produce 140 g of dry spirulina with a pond surface of 20 m²: (20(m²) × 7(g))/(1(m²))= 140 (g). 140 g of spirulina contains around 91 g of protein, which is more than enough to supplant 1 adult human and almost enough for 2. (Anyways, this spirulina diet has to be completed by other aliments). For the sake of modularity, recycling and, cost and time efficiency, we can fit this culture into a 20ft Container by splitting it into 4 ponds stacked on top of each other’s. Also, we know that it is better to have more than 1 ponds for security reasons. NB1: 20ft Container ref.: Length = 589.7 cm, Width = 235.0 cm, Height = 239.3 cm. 20ft High Cube Container ref.: L = 592.7 cm, W = 237,2 cm, H = 270.8 cm. We will choose to use the size standard of a general 20ft Container because it’s easier to find and cheaper than a High Cube. However, we can think that if it is part of a whole modular system where it’s more convenient to use High Cube Containers (because it’s better to live in a space with a higher ceiling) we should also consider using High Cube ones to make a green house. This is right, but because we will never use this unit under another one but always on top (to take as much sun exposition as possible) we can use the normal size.
Therefore, we can make 4 ponds of 5m² each. In order to feet into the size of a 20ft Container they should be: Length = 400 cm, Width = 125 cm, Height = 30 cm. (400*125 = 5m²) This size leaves some space to go around the ponds and put some technical elements: - 94.85 cm at the front and the back of the ponds (189.7 cm total), - 55.00 cm on the sides (110 cm total), - 29.82 cm above each pond (119.3 total). The ponds should be placed at the center of the greenhouse so that spirulina don’t get burn by the hot temperature and high light intensity present at the surface of the transparent walls. Plus, we need some space to install a shadowing system on the walls. Also, when placed at the center, it is easier to clean and to access to all of the ponds area. The structure of the container should be built out of steel rectangular tubing. We can make the walls with 4mm corrugated PVC transparent panels on both side of the steel structure. This will ensure a good insulation and a good enough resistance to climatic hazards. Also, this material is not 100% clear, it diffuses the light which is good for our case. The ponds are rectangular tanks made out of acrylic plexiglass stacked on a central rack. The rack is only a frame around the pond to give the pond as much light as possible. Although, at the same time, it has to be very strong because the load is 4000 kg. The ponds are filled with the culture medium until 20 cm high. Which represent 1000 kg each (4000 kg total). Agitation is provided by 1 big pump (need more details) connected to pipes which are directly attached to the 4 corners of each pond. At the end of these pipes there is an air stone for a better diffusion and a better agitation.
Corrugated PVC panel wall
Pond
Automated Curtain Mount for Light Deprivation System
CO2 Densifier Input
Spirulina Harvester
Nutrient Injector
2. Culture Medium In order to increase the volume of the culture the starting process is very important. 2.1. Find your spirulina strain source Find a local spirulina farm and get some samples. Then, analyze the samples with a microscope. It will be a good exercise. (Samples of a culture should be analyzed every month anyways). The strain must contain at least 75 % of coiled filaments (less than 25 % straight filaments, and if available 0 %) > Count how many of both type you see in each sample and establish a proportion. (It is good to create a data sheet to follows the evolution or to identify the possible different sources purity). The strain must contain at least 1 % of gamma-linolenic acid (GLA) based on dry weight. It will make it easier to harvest and limit degenerations. > Analyze (give to a laboratory) a dry spirulina sample. And establish the percentage of GLA (you can omit this step). 2.2. Culture Medium Preparation The culture medium is made to receive the culture. It will provide all the nutrients necessary for the growth and expansion of the spirulina. > Water: should be clean or filtered to avoid foreign algae. Potable water is convenient but, in most countries, it contains too much chlorine which is bad for the culture. Chlorine and chloramine can be neutralized using different techniques: - letting the chlorine evaporate by itself by letting the water for about 24 hours outside with air and sunlight (will not remove chloramine), - boiling the water for 15 minutes (will not remove chloramine), - filtering the water with a charcoal filter (will remove both chlorine and chloramine) will cost 5 to 30$, - using vitamin C, 1000 mg for 400 liters of water (will remove both chlorine and chloramine). (We could maybe use lemon?) Water rich in calcium is good but beware of the excess of calcium, it can cause mud. Brackish water may be advantageous but should be analyzed for its contents or tested. Seawater can be used under some very special conditions, which I won’t cover.
> Nutrient: see 3. Feeding the Culture 2.3. Collecting When your culture medium is ready and you are sure about your source try to get 20 liters samples for each of the 4 ponds. So, 4 containers of 20 l. Each of these samples should have a concentration of spirulina of about 10 g/l (dry matter in a volume) typically a Secchi disk at about 1 cm. NB1: Concentrated spirulina seed culture can be obtained either from the floating layer (if any) of an unagitated culture, or by rediluting a freshly filtered biomass (beware of lumps). 2.4. Transportation The transfer should be within at least 1 week at best less than 2 days. The transportation container should be aerated continuously (if not a concentration of up to 3 g/l is better, Secchi disk reading beyond 5 cm), in the dark (no direct sunlight) and kept at around 20°C. 2.5. Adding-up Spread your make-up culture from each of the 4*20 l containers into each of the 4 ponds (already filled with the culture medium). 2.6. Culture expansion It is advisable to maintain the growing culture at a fairly high concentration in spirulina after each dilution with new culture medium, about 0.3 g/l (the «Secchi disk» reading should not be above 5 cm). NB1: The color of the culture should be clearly green (otherwise shading is mandatory). NB2: The rate of growth is about 30 %/day when light and temperature are adequate and the make-up culture medium is based on bicarbonate (without carbonate). As the growth is proportional to the area of the culture exposed to light, it is recommended to maximize this area at all times (i.e. use the minimum feasible depth during the expanding area period, generally 5 to 10 cm). When the final area and depth (10 to 20 cm) are reached in the pond, let the spirulina concentration rise to about 0.5 g/l (Secchi disk at about 2 cm) before harvesting.
3. Feeding the culture The nutrients extracted from the culture medium by the harvested biomass should be replaced to maintain the fertility of the culture medium. 3.2. Carbon (Carbon Dioxide, CO2) Carbon is the main nutrient. In order to increase the productivity, for 140 g/day of spirulina we need 112 g/day of CO2 feeding. > Urine based feeding: increase the spirulina growth of 2 g/m2/day. The natural growth is 4 g/m2/day, after urine it’s 6 g/m2/day. An equivalent of around 75 g of carbon. Urine based feeding will be covered in detailed in the next part. > Sugar & Yeast CO2 aerobic reactor: has a theoretical CO2 production yield of 150% compared to the glucose input. The chemical reaction equation is C6H12O6 + 6 O2 → 6 H2O + 6 CO2 + energy. The reagents, C6H12O6 and (6) CO2 molecules have an atomic mass of respectively 174 u and 252 u. So, the reacting mass ratio is 174:252. Therefore, (174 × 112)/252=232 g of sugar a day to produce 112 g of CO2. However, the reaction depends on the catalyzing yield by the enzymes of the yeast. This process is not very stable and constant. But it’s still reliable even with a 50% instability allowance to produce a part of the final amount needed. > Human breathing CO2 collector device: a medium sized mammal such as the human exhale around 1 kg of CO2 every day. This is 9 times what we need for our culture! However, the air we breathe out is not pure CO2, it is composed by 14% O2, 78% N2, 4% CO2. In a closed room where 1 or more human is sleeping the concentration in CO2 increase. For example, outside it’s supposed to be 408ppm of CO2 and inside a small bedroom without ventilation it is in average 2400ppm during the night. In a classroom or office, it can reach 3000ppm. One solution would be to send the air of a bedroom (or a room with humans or animals) directly to the greenhouse. Hydroponic farmers usually create 1200 – 2000 ppm atmosphere for their culture. > Soda Lake: are already rich in CO2 and sodium bicarbonate. It would be an extremely valuable input allowing us to drain and change the medium of the spirulina culture.
If this living system is implemented near by a soda lake, this input is enough to supplant all of the carbon demand. > Volcanic gases capture: volcanoes release a big quantity of CO2. (~ H2O: 88%, CO2: 5.5%, H2: 2.9%, SO2: 2.7%). If this living system is installed in a volcanic zone, it would be possible to capture gases directly from the fumaroles and channel them to the spirulina greenhouse. (The sulfur dioxide emission could be a problem for spirulina. I have to do further research.) NB1: I didn’t mention feeding the culture with sodium bicarbonate because we need 2 to 6 kg by kg of spirulina. Therefore, when we harvest 140 g of spirulina, we’d need to inject around 560 g every day. This implies a big reliance on externally produced resources. Unless we live in area with a lot of trona ores that we could easily extract and transform into baking soda. It is therefore not sustainable. I didn’t mention the infamous internet technique to produce CO2 with baking soda (sodium bicarbonate) and citric acid because I found that we need 164 g of Citric Acid and 216 g of sodium bicarbonate every day! This is a lot and requires purchasing those elements from a factory. And for the acid it’s equivalent to 1233 lemons a day. NB2: The amount of CO2 or bicarbonate to be fed is adjusted so as to control the pH at around 10.4. A pH lower than 10.2 may cause an overproduction of undesirable exopolysaccharides (EPS), which make it more difficult to harvest. Usually, the carbon feed is equivalent of 40% of the spirulina produced. (about 0.8 kg of CO2 per kg of dry spirulina harvested). 3.2. N, P, K, S, Mg, Ca, Fe Spirulina requires those usual major biological nutrients, plus some micronutrients. Generally, the micronutrients and the calcium don’t need to be fed to the culture, because they are supplied by natural impurities from the make-up water and from the chemicals used as food for the spirulina. > Urine & Iron solution: all major nutrients and micronutrients except iron can be supplied by urine (from people or animals in good health, not consuming drugs). Iron can be supplied by a saturated solution of iron in vinegar mixed with some lemon juice or citric acid. - Urine: With a drip irrigation system, add daily doses equivalent to about 1.5 to 2 liters by 100 g of spirulina produced. Human produce around 1.5 l of urine a day. Sterilization can be useful: add 3.5 g of Sodium Hydroxide by liter of urine 24 hours before use. In our case: 2 l of urine for 140 g of spirulina every day.
- Iron solution: “Rusted Nail Soup” 10 g/l: put 50 g of rusted nails into 1 liter of vinegar + juice from 4 lemon or carambola (fruit located in South East Asia); keep it in aerated container (Hydrogen release) for 2 weeks and agitate from time to time. With a drip irrigation system, pour the solution for a total of 10 ml by 100 g of spirulina produced. In our case: 14 ml for 140 g of spirulina every day. 3.3. Micronutrients Solution Optional but useful to make the biomass easier to harvest, to transport and also to reduce the need for renewing the culture medium. Disolve the product in order, one by one, after the previous is completely dissolved. - ZnSO4,7H2O (Zinc sulfate heptahydrate): 20 g/l - EDTA Disodium Salt Dihydrate, 2H2O: 7 g/l (or Citric Acid: 10 g/l) - MnCl2,4H2O (Manganese(II) chloride tetrahydrate): 2 g/l - CuSO4,5H2O (Copper(II) sulfate pentahydrate): 0.5 g/l - MoNa2O4,2H2O (Sodium molybdate(VI) dihydrate): 0.35 g/l - Demineralized Water: q.s 1 l (note that with the time, this solution releases a bad smell of sulfide gas composed by toxic selenium vapor) With a drip irrigation system, pour the solution for a total of 0.5 ml by 100 g of spirulina produced. In our case: 0.7 ml of micronutrients solution for 140 g of spirulina every day. NB1: In some locations, the water contains too much calcium, magnesium or iron, that may become a nuisance by producing mud. In such case, pretreatment of the water is preferred. NB2: BEWARE of the contents in “heavy metals” (mercury, cadmium, lead and antimony), spirulina absorbs these (check regulations for spirulina and specifications of these fertilizer). NB3: Very generally the best and cheapest source of nitrogen (N) is urea (ammonia + CO2). However, its concentration in the medium must be kept below about 50 mg/liter. Excess urea is converted either to nitrates or to ammonia. A slight smell of ammonia is a sign of a nitrogen excess, not necessarily harmful; but a strong odor indicates an overdose. NB4: Fertilizers other than urea can be fed every month or so, but urea (or urine) has to be fed daily,
preferably based on the average production expected. 4. Harvesting Harvesting should be done in the morning. 4.1. Filtration Start the filtration pumps of each ponds top to bottom one by one at around 1 hour before sunrise. 4.1.1. Option 1: Filter/Scrapper Module Pumps (not simultaneously) will extract the culture medium up to the filter/scraper module (see pictures). The medium will fall inside a shallow tub with a fine weave cloth (mesh density around 30 – 50 µm) at the bottom and a big funnel underneath that will recycle the filtered water directly into the pond of origin. In order to select the destination pond, there is a servo-controlled flow divider valve at the end of the funnel so that the filtered water return back to where it came from. The filtered water should be light green because it contains small “baby” spirulina too tinny to be stopped by the filter. To facilitate the filtration, a scrapper positioned under the injector and activated by a lead screw will scrap the mesh continuously from side to side. When the filtration process is done and the biomass left in the tub on the filter looks like a very thick paste, take out the biomass and store or press and dry it. 4.1.1. Option 2: Centrifuge Module Similarly, pumps will drain the medium into the centrifuge. The centrifuge looks like a washing machine. The inner tub is made out of a fine weave cloth (mesh density around 30 – 50 µm) attached onto a rigid structure. With centrifuge force, it will collect the spirulina and let the water pass through its mesh. The water will then fall along the outer tub wall. And be pumped back directly into the pond of origin. Same as option 1, to select the destination pond, there is a servo-controlled flow divider valve. The filtered water should be light green because it contains small “baby” spirulina too tinny to be stopped by the filter. When the filtration process is done and the biomass left in the inner tub looks like a very thick paste, take out the biomass and store or press and dry it.
Harvesters : - 4.1.1. Option 1: Filter/Scrapper Module (i - 4.1.1. Option 2: Centrifuge Module (in the
in the bottom left-hand corner) e upper right-hand corner)
4.2. Weighting Weight the filtrate to get an estimation of the quantity of spirulina harvested. Filtered biomass contains 10 % dry matter (1 liter = 100 g dry spirulina) and 50 % residual culture medium. 4.3. Sieving Then the filtered culture passes through a sieve (mesh size about 200 µm) to remove any foreign matter such as insects, larvae, leaves and lumps of polysaccharide or muds from the bottom of the tank. 4.4. Dewatering Dewatering is accomplished by pressing the biomass enclosed in a piece of filtration cloth + a strong cotton cloth, either by hand or in any kind of press. The simplest is to apply pressure (0.15 kg/cm² is enough) by putting a heavy stone on the biomass bag. The expelled «juice» comes out colorless. When it turns slightly green, we must stop (otherwise too much product will be lost). For the usual thickness of cake (about 2.5 cm after pressing), the pressing time is about 15 to 20 minutes. Practically all the interstitial water (culture medium) is removed. The pH of the well pressed biomass is near 7 (neutrality). 4.5. Cleaning The pumps, the piping network and the Filter/Scrapper Module or Centrifuge Module should be purged with clean water after each harvest. Each pump is fitted with a purge valve that will let water flow into the network without leaking into the spirulina pounds. The flow divider at the end of the funnel has a 5th valve solely dedicated to purge. The water will be released in an external water tank that can later be recycle for other needs.
References _Spirulina guide Manuel de culture artisanale de spiruline - J.P. Jourdan (rev2018) _Urban farm unit http://20footurbanfarm.blogspot.com/ _Space station recycling system https://www.esa.int/Science_Exploration/Human_and_Robotic_Exploration/Research/Advanced_ Closed_Loop_System _Study about gasses emisson from composting https://www.researchgate.net/profile/Weijin_Wang/publication/45092519_Emission_of_greenhouse_ gases_from_home_aerobic_composting_anaerobic_digestion_and_vermicomposting_of_household_ wastes_in_Brisbane_Australia/links/0deec51ca4a5ab3d90000000/Emission-of-greenhouse-gases-fromhome-aerobic-composting-anaerobic-digestion-and-vermicomposting-of-household-wastes-in-BrisbaneAustralia.pdf _Study about CO2 in human habitat (room, office,etc) https://medium.com/@joeljean/im-living-in-a-carbon-bubble-literally-b7c391e8ab6 _Composition of fumarolic gas https://www.sciencedirect.com/science/article/pii/S0377027396000960 _Centrifuge filter for bio-oil http://www.simplecentrifuge.com/gallery-series-17.html _How to measure spirulina concentration http://www.spirulinaacademy.com/how-to-measure-spirulina-density/ _Automated light deprivation system http://www.gro-techsystems.com/automated-light-deprivation/
CO2 Densifier Input
Automated Curtain Mount for Light Deprivation System - Top Rail
Automated Curtain Mount for Light Deprivation System - Bottom Rail
CONCLUSION
Until now, there is no documentation about local spirulina farming. The existing projects in literature only deal with big scale spirulina factories, tiny house aquariums filled with spirulina, or primitive setups that are still too small and require a lot of human work. The closest project from mine I could find was for the space station, but still I couldn’t find enough documentation. This is why I felt the need for this spirulina farm supplying enough food for 1-2 people. However, even though, I gathered and organized a lot of information, my project still lacks a lot of information to build a final working system. I guess I need more field experience and I need to build working prototypes of this system in order to improve it. It is time to let this on the side. Later in my life I surely will get back to it. Doing this research made me learn a lot about different fields: philosophy, biology, chemistry, agronomy, but also engineering, 3D modeling, structural steel building, nutrition, well-being, and even more. Furthermore, this research made me realize that it is beautiful the fact that we could do a simple and short loop with spirulina. This is why I called this project “Spirulina Symbiosis”. Post Scriptum: To the people declaring that spirulina doesn’t look like food, I will answer that spirulina was present in the alimentation of Aztecs (Mexico) and Kanembu (Tchad) people. What we consider as food is a cultural construct. We can change it.