Undergraduate Student Lightning Presentations

we are moving into the Lightning presentation piece of our program and I would just note that if you haven’t noticed this symposium is very intentionally a cross-section of women at all stages of their careers and it’s part of our work to build a c3e community that can really support the recruitment you’ve heard this before from so no speakers recruitment retention and then advancement of women in this field and so one important piece of that is of course students so we turn now to them and we will have lightning presentations from nine undergraduate women from around the country they’ve come here today to share their work on a variety of clean energy topics with you and each presenter will have three minutes to present and then we’ll answer one audience question we hope you enjoy hearing about the amazing work these young ladies are doing as much as we do and I’ll turn things over now to Sarah guy a gross MIT student engagement coordinator who will introduce you to our presenters good morning thank you again I get the pleasure of introducing each of these outstanding undergraduate women to share their research with you so first we are going to have a Luca borsuk from University of Hawaii at Manoa she’s a junior majoring in mechanical engineering thank you so today I’ll be talking about effectively transparent front contacts for solar cells and this work was done this summer at Caltech with Professor Harry Atwater and dr. Rebecca SEF now look closely at the surface of a solar cell and you’ll find that it’s covered in a metal grid this is an electro that collects and transports electrical charge and while absolutely necessary it blocks the Sun from hitting the area of the solar cell directly beneath it so if we could reclaim these shadowed areas what would we get advice with more photocurrent and a higher efficiency even without changing its footprint so the question we asked was how can we make these front contacts effectively transparent to do this first we recognize that in the case of flag contacts instant light simply bounces back towards the light source where it can’t be used by the solar cell our design therefore would be three-dimensional and pyramidal in shape such that instant lighting a side wall would be redirected downwards where it could be absorbed by the active surface to do this we took a laboratory solar cell device and first let the graft a grid of flat conductive contacts and this would serve as a foundation for our pyramids which we made with nano scribe which is a super cool two-photon absorption printer that prints with nanoscale resolution and then finally we deposited a thin film of metal on the sidewalls such that they were very reflective and here we have the reflectivity of our contacts in the case of flat contacts on the left hand side you can see that those bright white stripes mean that light is bouncing back towards the light source back to our I however in the case of our three-dimensional contacts they appear much darker that’s pretty cool it means that light is being ripped redirected and in some areas towards the top they almost seem to disappear and these are areas in which the geometrical fidelity of the contacts was quite good so we quantified the photocurrent in some of these areas and found that we could regain up to ninety nine point nine six percent a photo current and that’s what I mean when I say that they are effectively transparent we also put our devices under a simulated solar spectrum and found that we could in laboratory devices increase the current density and solar cell efficiency to think about the future of these contacts of this technology I’ll first say that it’s still in basic research stages and work on commercialization has yet to be done however I can talk towards scalability which is a huge issue in the nanotech world how do we get something small made on a big scale and towards that we’re looking at a grab your style printing process so if you can imagine that making these contacts could be as fast as similarly cheap and easy as printing a roll of newspaper so with that thank you and I’ll take questions hi Erica that’s my thanks for your presentation I used to work at First Solar so I know how every little bit of efficiency really matters it looks like a lot of your experiments were done with very direct sunlight and I work in the Middle East where it’s a lot of diffused sunlight you get a lot of pollution a lot of sand how have you seen the effectiveness of your contact when

you’ve got kind of this diffuse sunlight coming down mm-hmm that’s a great question as you noted we use a very collimated beam that’s perpendicular to the surface of the solar cell but simulations done by my mentor Rebecca sev indicate that the three-dimensional contacts are more effective than planar contacts or flat contacts between the angles of 0 and 35 degrees of instant sunlight so there’s that the other pieces that we might think about pairing this technology with attract panel photovoltaic panel which I believe it is the direction the industry is moving in at least in terms of utility-scale PV farms single or double axes tracked and then finally since it is still in the research phase i would say that we I end up moving the contacts closer together so right now they’re about 40 microns apart and somewhat counter-intuitively if we make the spacing a little bit more dense we might give this kind of funnel effect where photons could bounce from one side wall to another and finally down towards the surface of the cellar saw so question thank you all right next up we have a sophomore here at MIT majoring in material science and engineering Reva Butte in ski thank you right good morning everyone today I’m going to be talking to you a little bit about my work in biofuel synthesis namely for methyl Penton all or for MP so why are we talking about 4m p with a branched methyl group configuration and a longer carbon chain length for MP intrinsically exhibits a high octane number or the efficiency to burn in an engine as well as a higher energy density than both isobutanol and an e 10 ethanol blend so for MP presents itself as a viable sustainable fuel but while it is currently efficient to consume yes it is not yet efficient to produce and that’s where my project comes in so in order to alleviate this I first looked at the current pathway for producing this biofuel which was developed by my lab and converts glucose in 24 MP and other byproducts using only enzymatic conversions from these titers which from the right to the left represent the product for MP the byproduct isobutanol and the unwanted intermediate isobutyrate i determined that there was a bottleneck or build up of isobutyrate in the system that was limiting for MP production and so what this indicated to me is that the enzyme that is used to convert isobutyrate into isobutyl co a known as i bu a was not doing its job i proceeded to hunt for alternative enzymes that would be able to complete this same enzyme version and i found one family of enzymes called propionate co a transferases or PCTs through literature review i selected two enzymes from two different host organisms known as Clostridium propionic um or CP and ralstonia eutropha known as re that i tested in my experiment i then cloned the genes that encoded for these enzymes into engineered plasmid vectors then taken up by E coli cultures I then inputted a feed of isobutyrate and measured an output feed of for methyl valerate or for MV using both liquid and gas chromatography so this bracketed process essentially was performed in order to assess the enzyme conversion efficiency of my different setups those setups being the first with no enzymes the second with the PCT from CP third the PCT from re and the fourth with the previously used IBO IBU a enzyme and this was my crucial finding I found that the PCT from the CP organism could convert isobutyrate into 4 MV at an efficiency of twenty nine point four percent which is over three hundred and fifty percent more efficient than the previously used i bu a this indicates that the fourth that the PCT from the CP organism could alleviate the bottleneck in isobutyrate build up in this pathway and be used as a crux for future study in for MP production pathways this work also sheds a hopeful light on the viability of metabolic engineering to develop sustainable sources of fuel for generations to come and finally I would like to thank dr. cristela Jones Prather dr. buch in the entire prater laboratory for helping me conduct this work as well as Shell Oil Company in my tea for funding it and of course c3e for hosting me here today and all of you women for being so welcoming and inspirational and now I’ll take any questions thank you thank you um so next up I would say I

guess just a peek back at this pathway here this pathway in the top right corner is the full pathway that goes from the glucose into the biofuel as opposed to this bracketed pathway so what’s next would be to assess how the PCT enzyme reacts in total pathway as in this bracketed pathway we’ve eliminated other variables so that way we could see how the efficiency of foreign p production compares to that of previous studies thank you okay next up we have olga y le Silva from Case Western University and she is a senior majoring in materials engineering well thank you for being here and I will discuss the Declaration of polyethylene and its relationship to photovoltaic cells and wires so why do we even care about the declaration of a polymer this polymer is actually used to coat the outside of every single photovoltaic wire and along with that it readily degrades in UV radiation kind of counterintuitive of people putting it up with solar panels so if this degrades to a point where the copper contact is revealed it can actually touch the metallic surfaces that hold up the photovoltaic cell and cause files as demonstrated in the picture above this is standard um kind of is established to prevent this by ul however the US standard is only for America and it is not internationally recognized so the wires that we get from China Germany and the u.s. have different chemical compositions and different lifetime performances while photovoltaic cells are created for approximately 20 to 25 years these wires or not so I evaluated how these particular wires degrade over time I did an indoor accelerate exposure as well as an outdoor real-life exposure followed by an outdoor exposure with an electronic load to mimic exactly what they experienced it hooked up to an actual solar cell using ftir and chemical analysis we found that the degradation pattern of the commercially available wires that we studied differs from the UL predicted degradation pattern so this is a problem if we cannot guarantee the safety of these wires we cannot guarantee the safety of residential homes and schools that these panels are being put on top of so since there is a difference I proposed you will reevaluate the standard that is established and since this standard is based off of the theoretical pure polymers that is usually study in a lab there’s no additives no plasticizers no dyes the commercially available wires do have all these so your L should standard should mimic the commercially available wires rather than the theoretical polymers that we study in a lab so I will now entertain any questions yes they actually fund me um so like they have expressed a lot of interest and right now they are reviewing the publication that has come out of this so we’ll see what that leads thank you all right next up we have Anastasia korla who is a junior at Tufts University majoring in physics and mathematics okay so today I’m going to be talking about verifying tritium relief models okay so what is a tritium release model tritium is a radioactive isotope of hydrogen that’s often used in fusion reactions so a tritium relief model models the release of tritium from a fusion reactor into the atmosphere and then using environmental transfer models

models the release of our models the movement of tritium through the environment and two people so fusion reactors have seen something of a resurgence lately I mean there’s been the new a RC reactor here at MIT and either of course is still in development and fusion could possibly be an excellent source of clean energy nuclear energy currently accounts for about eleven percent of the world’s electricity generation and fusion could provide a much safer way to do that however it’s important to know how a fusion is exactly so we can use tritium release models to sort of get an idea of that however a lot of these tritium relief models are almost 20 years old by now or older so what does this mean well twenty years ago when they were using the models to run calculations they had a lot less computational power available this meant that to actually do the calculations for the model they needed to use a lot more simplifications now these simplifications usually came in the form of simplifying integrals so that the actual code didn’t actually have to run any integrals nowadays we actually have a lot more computational power available and we can actually find numerical solutions to these integrals a lot faster and we can find a lot more solutions I mean back then they wrote everything in Fortran okay not everything they wrote in Fortran and nowadays we can use Mathematica which is a more sophisticated computational tool so when we actually compare the models we see that 20 years ago the calculations they got with their simplifications were three orders of magnitude less than what we get today when we run the same model without the simplifications so this is in units of bexar l per volume that’s the unit of radioactivity not actually a radiation dose so you can see from the graph that not only it’s a concentration higher it’s higher for longer okay so what does this mean so if these models that they use to estimate the safety of fusion reactors are under estimating safe risk then they might also be under estimating final dosages to people and the safety of fusion reactors as they calculated them 20 years ago might have been overestimated so by more accurately recreating these models and redoing these calculations we can actually get a better idea of how a fusion reactors are so going forward we’re going to look at modeling the rest of it to find the actual radiation dose risk to people right now we were just looking at concentration than air we’re going to actually look at what does the final dosage end up being for people okay now does anybody have any questions about this I’ll ask a question Kate Holly rocky mountain institute right death I’m curious to see how this might transform the market so if this is like what and how does this at applying a market opportunity so fusion reactors right now are not quite yet commercially viable so that’s maybe around 30 years down the line more or less so this wouldn’t change anything right now but it could dictate what happens going forward in the future okay thank you very much all right we have next up are another sophomore from MIT majoring in material science and engineering Caroline Lowe alright so today I’ll be talking about my work with lanthanide metal coordination polymer complexes and their potential application as a protective coating an offshore metal structures in the energy industry so currently there’s a growing interest in offshore energy resources for example offshore wind power is just starting to gain momentum in areas like Rhode Island and we’re seeing a new wave of interests and harnessing the energy of the ocean as a result there’s a need for a better protective coating to protect these offshore structures from the corrosive effects of the ocean now this is where lanthanide metal coordination polymer complexes can come in inspired by muscle fibers which are made up of iron rich proteins these polymer materials have strong mechanical properties and our self healing because they are bonded to metal ions in my work I use lanthanide metals europium terbium and lanthanum because they also make the material luminescent under UV light and the color that the material emits can change in response to environmental stimuli so imagine coding this polymer material

onto offshore metal structures and using their luminescent qualities to signal if there is a change in pH temperature or pressure by Matt damage the structure this work is still in its early stages and so we took before we begin to develop this as a commercial product we first need to better understand the luminescent qualities so you study these materials I make beads out of them because they are good test models the polymer I use this alginic acid which when I dissolve in water forms alginate then droplets of the alginate is added to a lanthanide metal salt bath to form these lanthanide coordinated with alginate beads finally the beads are coated with a ligand to pyridine to enhance the luminescent qualities when the beads are excited with UV light europium beads appear red terbium beads are green and lanthanum beads are blue if you combine all three lanthanides into one bead you make a yellow luminescent bead that can also change color in response to different environmental stimuli for example these beads are naturally acidic with a pH of 4 but if you subject them to a ph of 8 which is about the ph of the ocean right now they turn pink likewise heating them from room temperature to about 90 degrees Celsius causes them to turn gray but then then they regained their original yellow color once too once you cool them back to room temperature so so far I have developed a stable model to study these lands and I coordinated algini complexes and preliminary tests show that these materials are stimuli-responsive the next steps on my research are to quantify the luminescence and the toughness of the material and to see if I can correlate increasing mechanical stress to changes in color thank you are there any questions yes on a wind turbine to keep birds from running into it if they could actually see this luminescence and or when the things that you’re doing now does it keep whales from running into this I’m just thinking this of yes so this they are actually luminescent only under UV light so they don’t admit color under natural light all right next up we have I yella myla Moskowitz who is a junior at the University of Maryland College Park majoring in environmental science and technology hi so today I’m going to be talking about methane inhibition from anaerobic digesters to microbial fuel cells so manure is a significant contributor to greenhouse gas emissions one way to curve this is by using an anaerobic digesters enter weak digestion is using a waste product to create a biogas which can in turn be used to generate energy so what my project looked at was using the effluent or the liquid product from anaerobic digesters as a food source for microbial fuel cells now in anaerobic digesters methanogens or methane-producing organisms are dominant whereas in microbial fuel cells iron reducing bacteria are dominant so what we wanted to do was to inhibit those methanogens so there was no competition and the iron reducing bacteria could grow optimally so how he did this was through a biochemical methane potential test or we loaded inoculum as a microbe source and manure as a food source we then created anaerobic conditions and continuously measured for biogas with a gas chromatograph on the fifth day when we had maximum biogas production we added our different inhibitors then created anaerobic conditions again and continue to measure for biogas what we added was one iota form to BES or to bromomethane sulfonate three a 30-minute air purge or for a 24 hour air purge so what we found is the bottom line is our I oh deform worked really well at inhibiting our methanogens the 24 hour air purge worked well for four days but then biogas production continued our I Oda form is the sorry VES is the yellow line which worked really well at reducing methane production but not completely inhibiting it and the dark blue purple line is our 30-minute air purge which didn’t really work well at all so what does this mean this is particularly useful for people who are doing research in anaerobic digestion or microbial fuel cells but also in wastewater treatment in wastewater treatment plants they are have an aerobic digesters that art they are using but microbial fuel cells could be the next step where they are able to harness more energy so depending on which inhibitor you want to use if

you’re the retention time of your microbial fuel cell is less than four days you can use either of the two chemical additions or the 24 hour air purge if it’s greater than four days you should stick with either of the two chemical additions to make sure that there is no methane production later on thank you and any questions thank you can you comment on the mechanism of the BS or the iodoform please so the bes and the iodoform are both specific inhibitors so they won’t they shouldn’t affect the iron reducing bacteria but what they do is they affect the enzymes of the methanogens so they can’t produce any more methane you know which enzymes know okay next up we have isabella p notes from a florida atlantic university she’s a junior majoring in ocean engineering good afternoon so I will be talking to you about assessing the energy from the Gulf Stream using it for ocean current renewable energy so we all know that renewable energy has become so popular now so now the research and development is underway for ocean current renewable energy for for here for the US Japan South Africa multiple countries are starting to get involved so in the top picture right there is a simulation of what a turbine array would look like similar to what a wind farm is starting to look like we took that as an example the bottom three pictures are showing already testings for different companies and research places southeast national marine renewable energy center is already testing propeller rotation while the other two pictures in the middle and on your left right I don’t know our testing their prototypes the middle one is the acontece prototype from a company from santa barbara california and the anadarko prototype is from a company in Texas so to understand what kind of turbine we should create for the Gulf Stream off the coast of Florida we need to understand that energy density coming from the Gulf Stream so the picture on the top is from hicom the hydro coordinate ocean model which is showing the surface currents globally over a span of three years from this data source we were able to use the kinetic energy flux equation to figure out what our average current energy would be off the coast of Florida which can be seen on the picture on the bottom but our research team and I wanted to a more precise number so we had to take our own measurements our measurements were used from three different sources two sources were public data that anyone can see and the third source was data that we ended up using the first public source with the drifter measurement system which is cut from the world ocean circulation experiment which used buoys around the world the second public source is which can be seen in the middle pictures is an acoustic Doppler current profiler which was mounted to the bottom of a boat which traveled between the Bahamas in Florida that location and path can be seen in the bottom picture on the top the third source which was used with my school Florida Atlantic University and southeast national marine renewable energy center we used a bottom mount acoustic Doppler current profiler which can be seen in the other picture and we posted it and they I think off the coast of Jupiter which can be seen on the map at the bottom these measurements which allowed us to show different types of data the data from the drifter measurements you can be seen in the picture all the way to your left shows the location of the buoys off the coast of Florida all the way to North Carolina the top right picture talk yeah top right picture shows the bottom mounted acoustic Doppler current profile on the boat and the bottom right picture shows the bottom mounted one and these three data sources show the average can be about three point 0 kilowatts per meter squared which is fifty percent more than what the numerical data showed these datasets also show us what the perfect location for our turbines were thank you any questions hi the one project I’m familiar with it was in the East River in New York and the propellers fell off and so are you going to take this to the next level to find out what the how these streams are affecting the viability of the equipment so on what this research was just for location and everything on the next step like you said is to the design process so each

location for the turbines are going to be have different designs because each stream or each ocean area or current area is going to have a different energy density so some designs may or may not work in certain places because of the energy density thank you okay next up we have maintained q who’s a sophomore at Harvard College majoring in chemical and physical biology hi everyone so today I’m going to be talking to you about catalyzing the oxygen reduction reaction with manganese 3 hangman porphyrin so we’re interested in oxygen reduction reaction or Orr because it’s the reaction that occurs at the cathode of fuel cells and briefly fuel cells are important to the sustainable energy question because they’re able to convert the chemical energy stored in hydrogen and oxygen bonds into useable electrical energy but the current problem with fuel cells is that they’re their reactions are catalyzed by platinum which is an extremely expensive catalyst so there’s been a hunt for cheaper and earth-abundant catalysts my lab in particular has been looking at methylated porphyrins and in particular we found that manganese 3 tetra phenol porphyrin is able to catalyze oxygen reduction so we were interested in studying the hangman version of this porphyrin shown at the bottom here in order to determine its catalytic ability towards orr and also the reaction mechanism that this porphyrin induces on the reaction so to achieve our goal we first had to synthesize this target porphyrin at the bottom shown here and this required three steps the first of which being forming the porphyrin and then we had to detect the methyl ester group to form carboxylic acid and lastly we inserted the manganese into the porphyrin after we synthesized her porphyrin we had to perform some electric electrochemical experiments on the porphyrin in order to determine its catalytic ability and the first experiment we performed is called cyclic voltammetry or CV which is a method used to study redox active molecules and this experiment basically allows us to plot the current generated from the reaction as a function of the potential applied to the solution which includes our porphyrin and some other stuff and the purpose of this experiment is to determine if our catalyst is redox active or not here you can see a graph of a CV that we took and we were interested mostly in the leftmost wave because when we add oxygen and acid to the solution which are necessary for the reaction we see that there’s a huge increase of the current and this large increase of the current tells us that our porphyrin is catalyzing the reaction and the second experiment we performed is called rotating ring disk electrode or rrd which is similar in setup to CVS but here the purpose is to determine the efficiency of our catalyst and we do that by determining the amount of hydrogen peroxide formed versus the amount of water form by the reaction the hydrogen peroxide being the undesired product and then the water being the desired product here you can see a graph that we obtained using our de and as you can see the amount of hydrogen peroxide form is extremely low or below two percent and so we were able to conclude that our ferdig yield in water was ninety-eight percent which is extremely good so in conclusion we were able to find that our manganese three hangman porphyrin is redox active and catalyzes the oxygen reduction reaction with pretty good efficiency and although we’re still in the process of determining the mechanism for this reaction we think that this is a promising approach to designing better catalysts for fuel cells and I like to finish by thanking my p.i professor Daniel nocera as well as my mentors d like and Guillaume and also the rest of the nasarah group who helped me with this project and thank you all for listening hi excellent presentation I’m a couple of quick questions how does the performance of this catalyst compared to platinum and then secondly how are you going to actually test it on a fuel cell next sure that’s a very good question and I’m afraid that currently were at some out of pretty pretty preliminary stage for this catalyst and so it doesn’t quite match up to platinum yet but it is better than a lot of the other catalysts that we’ve tested previously it’s better it’s faster and it’s it’s more efficient as i mentioned i think the next step towards looking at putting this in fuel cells is to be able to actually do this reaction in water because currently we’re in an organic solvent acetonitrile and that’s not very good if you want to use it in fuel cells

so the next step would be to put it in water and also for us to be able to determine the mechanism of the reaction will be able to help other scientists be able to better synthesize or look for different kind of catalysts that corroborate the mechanism of the reaction and hopefully be able to progress down the road from that okay finally we have our last presenter Julia belk who is a junior from MIT in electrical engineering hi so this summer I did research on magnetics for high frequency power converters through the MIT Energy Initiative and first quick recap of power converters in general so the rectifier in your laptop charger is a really familiar example of a power converter that everyone uses every day and that converts sinusoidal voltage voltages and currents that come out of the wall outlet into DC voltages and current voltages and currents at your laptop input and these devices are everywhere in modern electronics so power conversion research has three goals making smaller cheaper and more efficient converters and one way that recent research has been achieving these goals is by designing the circuits inside the converters to operate at higher frequencies one roadblock to doing this is that to design these converters you need data on the magnetic materials for your inductors and transformers at the frequencies you’re going to be operating at and because I converters have previously been designed at 1 megahertz or lower frequencies this data wasn’t available at higher frequencies so here’s you can see some standard manufactured data that uh that covers this frequency range but there is a gap of data in around the two to 20 megahertz range which we think is very good for realizing smaller converters so we went out to gather this data for a lot of materials in this frequency range characterizing it for its efficiency which is the data you need to to design your magnetic components so to measure the material and get the data that people that designers need we built an inductor with the material we’re interested in a toroidal inductor as pictured here and in essence we resonated it at the frequency wherein we were interested in and then measured how damped the resonances which you can do simply by measuring the output amplitude of the output voltage and the amplitude of the input voltage and that shows how damped the resonances from which you can tell how efficient the core material is so here you can see our results and the thing to note is that um the on the y-axis is a performance heuristic so higher is better performance and we found materials that are significantly better than those that manufacturers had previously made data available for and that suggests that you can build smaller and better converters by operating at higher frequencies using these materials that were not previously measured for these applications so if anyone has any questions thank you so these are all fairly standard materials that were shown in all of these plots they’re very comparable on cost um the the difference is just that the materials we measured had typically been used for radio frequency applications it just hadn’t been measured in the same way but they’re all very comfortable on cost thanks