Maximizing the production of hydrogen from green algae

[guitargirl32597]

Hello!
I am trying to find a way to accurately measure the production of hydrogen gas. I will be using green algae to produce the hydrogen. what are some ways to measure the volume of the hydrgen gas? I do dont have access to a gas chromatograph.

thanks,
Hannah

[guitargirl32597]

Hi everyone!
I am conducting research to find a way to increase the efficiency of hydrogen production by green algae. I am currently trying to find a way to measure the amount of hydrogen produced.
Would using the displacement of water be a practical way to do so? or would the hydrogen just bubble out of the water?
Also, what are the end products of photosynthesis in green algae? Is it just hydrogen? or are there others like CO2 (from cell respiration)?

Thanks in advance,
Hannah

[SciB]

Hi Hannah,

That’s a really great project you have chosen! There are lots of scientists working on that problem right now and hopefully they will be able to find ways to make algae produce enough hydrogen cheaply to use as fuel in place of gasoline. I did some reading about how to pump up hydrogen (H2 for short) production from algae and here’s a good description of the current research: http://en.wikipedia.org/wiki/Biohydrogen_reactor

Apparently if green algae are grown in a medium that is low in sulfur (that is, sulfate, --SO4 ions) their normal photosynthesis pathway shuts down and they switch to anaerobic fermentation and make H2. The enzyme that catalyzes synthesis of H2 is called a hydrogenase and it only works in the absence of oxygen. That’s why the algae growth medium has to be anaerobic (‘without air’). When algae are growing normally in sunlight with carbon dioxide (CO2) they produce oxygen (O2). The oxygen your body’s cells need for metabolism comes from plants, and single-celled algae account for most of it. So they are important!

Once the algae switch to H2 production, however, you can collect the gas by displacement of water from an inverted graduated cylinder to measure how much is being made per unit of time. Here’s an article that shows you how to do that: http://www.plantphysiol.org/content/127/3/740.full

This paper is pretty technical and if you need help going through it let me know. It seems to have all the information you would need to develop a really good project on algae H2 production. Do you have a source for your algae culture? Make sure you get one that does produce H2 when cultured in the absence of sulfate.

There are a lot of variables you can test—temperature, sunlight, algae density, types of nutrients and how much, and type of algae. I’m sure you’ll have more questions, so please keep in touch with scibuddies as your project progresses.

Best wishes,

SciB

[deleted-71625]

Hello Hanna,
Thanks for your question. I'm curious to know which project you are doing; is it from this site?
Without knowing your procedure, I will help as best as I can. Hydrogen gas can be measured different ways, the most common way and available to students (you should be able to acquire the materials and safety equipment from your Chemistry lab at school) is water displacement via gas production.

An inexpensive way to measure gas production is to use water displacement. Basically how this works is that you will have a measured amount of liquid (water) in a beaker. Hydrogen gas (source of energy) produced by the reaction (from the algae hydrogen production) will displace the water by adding volume. Then you can determine the displaced water (the total measurement of the water after the introduction of the gas minus the volume at the start of experiment).
http://www.ehow.com/how_7878127_measure ... ement.html
http://www.ehow.com/how_8070726_collect ... meter.html. You don't have to use a Eudiometer, you can use an inverted burette (just needs to be a tube with measurements on the side, so you can read the displaced water level). I suppose, if you really don't have those materials, you could use some sort of other glass measuring cylinder.

By measuring the amount of gas produced, you can determine the energy created. Here is a fairly simple setup on how to obtain the gas from your algae and measure the displaced water: see figure 1 for the setup.
All you need is the bottle of algae, a silicone tube from the top of the bottle to the beaker of water (make sure the seal is tight, otherwise gas will escape before it is measured), a rubber stopper, a burette (get from chemistry lab).
http://www.plantphysiol.org/content/127/3/740.full. You can even use this as a resource in your research section of your project.
Here is the procedure you can use to measure the produced gas (from another experiment): https://www.sciencebuddies.org/science- ... #procedure

Let me know if this helps and if you have other questions.

[guitargirl32597]

Thank you! I read through the article you recommended. It was helpful, but I am still a bit confused about the set up of the system used for the water displacement. After the H2 gas enters the inverted burette, what happens exactly? Would a diagram of the set up be similar to the diagram labelled "Method 1" on http://mypchem.com/myp9/myp9e/myp9e_htm/moles2.htm ?

Thanks for all your help,
Hannah

[SciB]

Hi Hannah,
Yes, the diagram in 'Method 1' in the link from your previous email is similar to what you would use to measure the volume of the hydrogen gas produced by the algae. You can see that as the gas bubbles up into the closed buret, the water is pushed out. The buret has a scale on it in milliliters so you can use that to measure the volume of water pushed out which is equal to the volume of H2 gas produced. Here's a picture of a setup for measuring H2 production in algae: http://www.springerimages.com/Images/Li ... 9-9415-5-4
You can see how they have the algae growing in bottles with stoppers and tubing to conduct the gas into the cylinders for measurement.

Do you have access to a lab where you can get the equipment needed to do the experiment? I can help you with putting together the setup once you have the parts. Please post again to this thread.

Best wishes,

ScB

[guitargirl32597]

Yes, I do have access to a lab where most of the equipment is a available, but I may need to purchase tubing, which should not be a big deal. I would definetly like some help with the setup!

Thank you so much!

[SciB]

You are certainly welcome. I will try to answer whatever questions you have and help you do a great project. Keep posting to SciBuddies. We're here to be your virtual mentors.

Cheers,

SciB

[guitargirl32597]

So, I have decided to use two independent variables: light intensity and algal density. I can measure the light intensity with a light sensor to regulate it, but how can I calculate/measure algal density? and what units would I use?

Thank you for all your support

[SciB]

Hi Hannah,

You picked two good variables to test since light affects algae growth rate and the density affects H2 production.

In regard to your question about how to measure algal density, we use a hemocytometer and a microscope in the lab to count cells. If you are not familiar with the hemocytometer, here's a good youtube video that shows you how to use it: http://www.youtube.com/watch?v=pP0xERLUhyc

Measuring density this way will give you number of cells per milliliter. In papers published in scientific journals you may see the amount of algae expressed as dry weight which is just what it sounds like--the weight of a specific volume of your alga culture evaporated to dryness. I prefer to use actual cell counts because it is simpler and can allow you to distinguish dead cells from live ones by using the vital dye trypan blue.

Which alga did you select to do the experiments? Try to get one that is a good candidate for actual use in industry because then your project will have real-world significance.

What are you planning to use as a light source for growing the algae and how are you going set it up so that different cultures receive different light intensities? Did you research the literature to find out what the range of light intensities should be? Remember you need to keep the temperature, gas flow rate, stirring rate, and volume of growth medium constant while you vary the light intensity.

I'm sure you will have more questions, so just keep posting.

Best wishes,

SciB

[deleted-71625]

Hello Hannah,

SciB gave you some excellent resources and ideas. If you don't have access to a hemocytometer, here is another tool you can use to measure density of algae and is low cost:
http://www.aquaticeco.com/subcategories ... ring-Stick. Just remember that this tool gives an estimation, so that will be need to be taken into account. Hemocytometer, though, is really the most accurate way to measure density and is relatively low cost. You can do a search on Amazon and they have them for about $25, not including dye or cover slips, but they require a bit of practice to fill the cells and do the prep--but if you have time to learn and the funds to do it, then I say go for it!

Let us know if you need more help.

[guitargirl32597]

SciB,

Thank you for the link to the YouTube video; it was helpful and informative!

The alga I have decided to use is Chlamydomonas reinhardtii. I have decided to use this because is it relatively inexpensive (so it will be available to me, and it is accessible in the real world).

I think I will use these light bulbs as a source of light (there is not a large enough window in the room I will be working in). http://www.amazon.com/Full-Spectrum-Lig ... light+bulb
Do you think these light bulbs would be good to use? if not, what do you think I should use?

To alter the light intensities of the light I will change the distance between the light source and the culture. Not much research has been done is this area, so I have not been able to find any literature regarding optimal light intensities for Chlamydomonas reinhardtii.

Thank you for all your help,
Hannah

[SciB]

Hi Hannah,

I'm glad to see you are well on the way to doing some experiments for your project. C reinhardtii is a good choice for your algae as it is being studied as a possible commercial hydrogen producer.

The full-spectrum bulbs you picked seem to me like a good choice since they are supposed to mimic daylight, and they give off a lot of light with little heating. You could check the scientific literature to see what other scientists use as a light source for growing C reinhardtii, but i think these are fine. Just be sure to keep the temperature, liquid volume, stirring or bubbling rate constant so that the only thing you are changing is the light intensity or the algal cell density.

Before you start the actual experiments, i would do a growth curve for your particular strain of algae, with your culture medium, light, temperature, etc. What this means is that you add a known number of C reinhardtii cells to a specific volume of culture medium and let them grow under the lights for a couple of days. Take a sample at time zero and count the number of cells, then take a sample again after a couple of hours and see how much the number has increased. Do this for as as long as the cell number is increasing. Eventually the cell density will become too great for the nutrients in the culture medium and growth will start to slow down and eventually stop. You plot number of cells per milliliter on the y axis against time on the x axis and this is your growth curve. The y axis is a logarithmic scale and the x axis is linear. This gives an S-shaped curve. The linear part of the 'S' is what is called exponential growth and that is the range of algal density where you want to do your experiments. Here's a website that explains more about this: http://www.marine.csiro.au/microalgae/m ... 20rate.htm

Keep us posted on your progress and let me know if there are any details you need help on. I am looking forward to hearing about your results!

Best wishes,

SciB

[guitargirl32597]

SciB,

I will definitely read some scientific literature to see if there is a better light source and what others have used in their experiments.

I will probably do a growth curve! Thank you for the reference to the link about how to do it.

Also, how long do you think my trials should be? The literature I have found so far does not include the trial lengths.


Thank you for all your help,
Hannah

[SciB]

Hi Hannah,

I can't tell you how long you will need to grow the algae to get statistically meaningful results because your conditions--light, temperature, nutrients will be different from those of some other lab. The growth curve will tell you how fast your algae reproduce and how long they will survive under your culture conditions.

What I mean is that you will have to do some test experiments first to determine the growth curve and to measure H2 production. Then you will know how long you have to grow the algae to run your experiments. Remember that you need to do a minimum of three algae cultures for each test condition and average the results in order to do statistical comparisons on your data. When you plot your values they should be expressed as the mean plus or minus the standard deviation.

Good luck and let me know how you are progressing. I am interested in what you find out about how light and nutrients affect H2 production by this alga.

Best wishes,

SciB

[guitargirl32597]

Hello! Sorry I have not posted recently, but school has started up, and my research project is about to begin. However, I have just found out that sulfur-deprived TAP medium (the medium I was planning on growing C. reinhardtii in) is very expensive to make, and is not feasible. Does anyone know of any mediums that are free of sulfur and can sustain the conditions necessary for green algae to survive? The medium has to be free of sulfur in order for the algal cells to reach anaerobisis and produce hydrogen.

Thank you!

[SciB]

Hi GG,

I know what you mean about being busy when school starts!We have three new students in the lab.

There are lots of synthetic media that you can make yourself. I will check online for the type of medium you need and see what i can find. Did you call Carolina Biologicals and ask them if there's something you can substitute for growing your algae? They have really experienced people working for them and are always willing to help young students.

Don't be shy about asking for donations. I teach a lab methods course and there are several scientific companies who regularly donate supplies and loan equipment for the course. Find a company that sells the medium you need, call their tech support desk and tell them you are a student working on a science fair project with a limited budget. They might send you some free samples--enough to do your experiments!

I will get back to you after I've done some more reading about algae growth media. Let me know if you locate a company willing to donate what you need.

Best wishes,

Scibee

[guitargirl32597]

Hi SciB,

I did not think about calling Carolina Biological, but I will definitely do that as soon as I can! I have found a lot of hydroponic plant nutrient deficiency lab kits that come with a medium I could use, however, I do not need an entire kit, just the one medium without sulfur in it. So, I would be wasting a good bit of money considering I would need to buy several kits in order to have enough of the medium to carry out my experiment.

Also, if Carolina Biological cannot help, I will call the University of South Carolina and see if they can help me.

Thanks for all your help,
GG