Testing the Charcoal Stove!

At long last, we had the opportunity to test our stove! Our goal was to boil 1000ml of water using 200g of charcoal.

Strengths of our stove:

- Our charcoal started burning pretty quickly and maintained a good flame.

- Charcoal ash fell through grate at the bottom of the charcoal holder successfully.

- Side wall vents did a good job of providing air flow to the fire. However, if we redesigned the stove we would add a sliding panel to have an adjustable vent cover to regulate air flow. 

- Oven and oven top were quite warm, but not really hot enough to cook anything. I'm still skeptical of whether the oven feature would be used whatsoever by people in developing countries, as most of the food cooked in Latin America and Africa is done on a stovetop. 

- Apart from the grate that the pot sat on, the stove was structurally strong and stable despite the wind.

Weaknesses:

- When the fire started, it was quite smoky and the smoke flew upward toward the pot instead of through the air vents. This was unsurprising because our air vents were located beneath the charcoal holder. If we redesigned this stove, we would build a small chimney to direct smoke out of the top, or position the vents at the same level as the charcoal.

- The biggest issue with our stove was that the radiator covering that the pot rested upon was not structurally sound. As the grate heated up, the metal began to bend, melt and break so much that we had to move the pot halfway onto the oven side of the stove for support. This reduced the temperature of the water because it was exposed to less direct heat. The grate was also lacking support from the walls that it rested on because we had mismeasured the wall heights and had to insert a makeshift piece of metal to close the gap. Using a stronger material for the grate and creating more structural support beneath the grate could help overcome this problem.

                                                 

- The ash tray was too hot to touch. We could have put a non-metal handle on the drawer so that it could've been pulled out safely while the fire was burning.

Water temperature:

                       

We recorded the water temperature every 7 minutes. The water temperature generally increased and then leveled off over time. The point at 13 minutes when the temperature went down was when the charcoal container gave out and some of the charcoal fell into the ash tray. If this hadn't happened, I think we would have been able to boil our water successfully.

I think that we could have increased the water temperature more quickly by reducing the distance between the charcoal and the pot by making our charcoal container slightly smaller. We also could have afforded to reduce the height of the stove in general, while also making the oven slightly narrower, in order to concentrate the heat better. 

Building the Charcoal Stove

Constructing a charcoal stove out of sheet metal was an incredibly new experience for me, as I had never worked with metal before. Though my group had conceived of our prototype with cardboard and duct tape, building a stove out of sheet metal and rivets required a new mode of thinking and came with new challenges. Initially we began to build by focusing at one part at a time, but we very quickly learned that we needed to meticulously plan out each step of the process beforehand. For instance, if we bent our metal into a box before drilling the holes for the rivets, it would become very challenging to maneuver the drill in that space. 

Therefore, we planned out our tasks chronologically and drew diagrams of different parts: 

Cutting and shaping the sheet metal was tricky, although it was quite thin. We used a sheet metal shear for the major cuts, and olfa knives and tin snips for the smaller cuts. In order to bend the metal into parts with 90 degree angles, we used a metal press or weakened the metal with an olfa knife and then carefully bent it over a table ledge or a heavy square piece of metal.  

                   

Since we obviously couldn't bind our stove together with duct tape in the final model, we used rivets - metal mechanical fasteners used in aviation - to connect our sheets of metal together. To join two pieces with a rivet we had to create tabs that would overlap with another sheet of metal. We also had to drill holes in the metal for the rivets.                                                                                                                                                             

                      

One of the issues we encountered was how to attach our grates to the bottom and top of the charcoal container. Initially we attempted to wedge the bottom chicken wire grate between the walls of the container and secure it with rivets, but this distorted the form of the trapezoid too much, so we rebuilt our side wall pieces to have tabs on the bottom and riveted the chicken wire to the tabs.   

After making side wall pieces with tabs and rivet holes, we cut out an air vent and covered the gap with radiator covering so that someone wouldn't be able to stick a hand into the vent while cooking, and also so that there wouldn't be excessive air flow to the fire. While we initially wanted to create a cover that could slide over the vent partially to regulate air flow and thus alter the intensity of the fire, we were not able to figure out the logistics of this design given time constraints.

      

We bent our metal into a rectangle, added the sides, and then riveted it all together. Unfortunately we had the mishap of making the long sides of our stove an inch short on both sides, so our short sides were an inch too tall. We fudged the difference by adding a long strip of sheet metal to cover the gap on either side, but the structural integrity of our stove certainly suffered from this mistake.

    

We hinged a grate made of radiator covering to cover the charcoal holder and made a top for the oven. It was surprisingly challenging to line up all of the wholes needed to hinge the grate to the stove.

Finally, we attached the stove door with a hinge and created a simple latch with a hook and eye latch.

   

At long last, our shiny aluminum stove emerged from the ashes looking quite like the cardboard model we had created!

Charcoal Stove Cardboard Prototype

Before constructing our prototype out of sheet metal, we built our charcoal stove out of cardboard, to gain a better understanding of whether our initial design ideas were structurally viable.

We created a rectangular box with a divider to separate the oven from the side 

that would hold the charcoal. 

We created two vents on the side walls of the charcoal compartment.

An ash tray with a pull-out tab was added to collect charcoal debris.

A trapezoidal container with a grate on the bottom will hold the charcoal 

and allow ash to fall through.

A door with a latch was added for access to the oven.

A charcoal grate on top of the charcoal holder will serve as the high-heat stovetop, 

while allowing easy access to the charcoal underneath. Although we initially wanted a circular removable

 grate so that there would be less space for smoke to escape, we couldn't find a way to execute this idea.

Our final cardboard product.

Charcoal Stove Design

After learning about the environmental, health, and economic concerns related to cooking with biomass fuel in developing countries, my teammates and I set out to design and build an "improved" charcoal stove for use in underserved communities.

Our primary design goals were to:

1. Improve insulation & smoke control
2. Low cost & local manufacture

Secondary design considerations included:

- Range of temperatures for cooking

- Air flow

- Portability

- Safety

- User friendliness

-Aesthetics

- Simplicity

When embarking on the brainstorming process, we had a simple iron charcoal stove from Ghana in front of us as a reference:

The key features of this stove are its trapezoid form to evenly direct heat to the cooking 
grate, and an opening beneath the charcoal grate for ash to fall through and also for ventilation.

We generated the following ideas:

Drawing inspiration from my old fashioned wood stove at home (rough sketch pictured above), we decided that a dual stove and oven function would allow for a greater range of temperatures for cooking while retaining as much of the heat produced as possible. Food requiring the highest heat could be placed on a burner directly above the fire source, while other items with lower heat requirements could be placed in the oven, or on the surface above the oven. We also decided to retain the trapezoid shape of the charcoal holder in the Ghanian stove. Our design included a sliding ash try that would sit beneath the charcoal and collect dust that fell through the crate for easy removal. To improve air flow to the fire, we decided to include two air vents on the lower side walls. We hoped that these vents would also channel smoke out of the bottom of the stove, rather than the top.

Rough sketch:

Side view of our double grate, charcoal-holding apparatus:

Personal Energy Consumption Estimates

From September 29th through October 1st I recorded my energy consumption from different activities, including using lights, charging my computer, and cooking. In recording my energy use, I did not include using the lights for less than 10 minutes, for instance while using the bathroom, because I discounted this data as "noise" that wouldn't severely effect my overall estimation.

Here are my calculations, by day.

Watt hour (Wh) = watts * hours

Sunday, September 29th

- In room: 60W*1 bulb*1 hr = 60Wh
- On boat: 60W*6 bulbs*1 hr = 360W/10 people = 36Wh
- In library: 60W*3 bulbs*2 hrs = 360W/2 people = 120Wh
- In room: 60W*3 bulbs*6 hrs = 1080 Wh
- 2 computer charges: 60W*3hrs*2 = 360Wh

Sunday Total: 1656Wh

Monday, September 30th

- In Sports Center: 100W*55 bulbs*1 hr = 5500W/25 people = 220Wh
- Class in science lab: 100W*4 barlights*6 rows*2.5 hrs = 6000W/15 people = 400Wh
- In kitchen: 100W*4 bulbs*2 hrs = 800Wh
- Meeting in science lab: 6000W (from above)*1 hr = 6000W/10 people = 600Wh
- In room: 60W*4 bulbs*4.5 hrs = 1080Wh
- 2 computer charges: 60W*3 hrs*2 = 360Wh
- Phone charge: 100V*0.2 A = 20W*3 = 60Wh

Monday Total: 3520Wh

Tuesday, October 1st

- In room: 60W*4 bulbs*3 hrs = 720Wh
- In kitchen: 100W*4 bulbs*1 hr= 400W/3 people = 133Wh
- In science classroom: 6000W*2 hrs = 12000W/10 people = 1200Wh
- In office: 60W*3 bulbs*1 hr = 180W/4 people = 45Wh
- In office: 60W*2 bulbs*1 hr = 180W/2 people = 60Wh
- In living room: 60W*6 bulbs*1 hr = 360W/8 people = 45Wh
- In room: 60W*4 bulbs*6 hrs = 1440W/2 people = 720Wh
- 2 computer charges: 60W*3 hrs*2 = 360Wh

Tuesday Total: 3283Wh

Three day kitchen estimates:

- 2 refrigerators: 600W*72 hrs = 43200W/8 people = 5400Wh
- Cooking with stovetop: 2000W*2 burners*3 hrs total = 12000W/8 people = 1500Wh
- Dishwasher: 1000W*6 washes*1.5 hours = 9000W/8 people = 1125Wh

Kitchen Total: 8025Wh

Three Day Total: 16484Wh or 16.484 kWh

Average energy use per day: 5.5 kWh

Source used: http://www.donrowe.com/inverters/usage_chart.html

I estimate that over three days I used about 16.5 kWh of electricity. This is definitely an underestimate because I didn't count the bulbs closely in every room I was in, or record the exact amount of time in each place. Since the weather was particularly excellent during these three days, I spent a lot of time outside, so I assume that my average daily energy consumption is actually higher. From doing this exercise I realized that my energy consumption is lower on the weekends, when I spend more time outside and less time in class. Also, I spend a lot of time with my friends in Scoop so my personal energy consumption is lower. Kitchen appliances, namely the refrigerators, stove, and dishwasher, consumed the greatest amount of energy by far. 

Everyday Technology Power Estimations

Here are my very rough estimations for the power usage of some common technologies: a light, TV, computer, car, motorcycle, refrigerator, oven, and radio. I didn't use internet so these estimations must be taken with a grain of salt!
 

Sampurn(e)arth Reforming Waste Management in India

Indian cities generate a massive amount of waste, most of which is dumped onto the open ground. Mumbai alone produces more than 10,000 tons of waste per day. Besides being an environmental travesty, waste pickers scavenge through the debris, searching for useful materials that can be sold or repurposed.

Sampurn(e)arth, a social enterprise start-up, is working to change how waste is managed, or unmanaged, in Mumbai by sorting waste at its source and "decentralizing waste management." The company separates wet and dry waste, and then transforms the wet waste into cooking gas and organic fertilizer at a biogas plant. The dry waste is then recycled.

What I find most powerful about Sampurn(e)arth's project is that it has partnered with Stree Mukti Sanganatha (Women's Liberation Organization), which includes an organization of female waste pickers. These waste pickers are trained to sort the waste and operate the biogas and composting systems. The benefits to these women appear to be manyfold - the organization pays them a living wage, social insurance, safe working conditions, and a livelihood that is not only dignified and empowering, but also improves the urban environment.

To read more click here. Visit Sampurn(e)arth's website here.

I Survived the Water Challenge!

Today marks the end of my participation in the Water Challenge, a week-long experiment between Olin Affordable Entrepreneurship & Design students and Wellesley Engineering students. The challenge required that we obtain all drinking, cleaning, and washing water from locations outside of our residential buildings. For me, this meant that I was not allowed to use the toilet, take showers, wash laundry, or use any sink water for drinking or washing in the Sustainability Co-op (Scoop) where I live. While the challenge seemed daunting and unmanageable, I embraced it as an opportunity to gain some sense of how difficult it is for people in underserved communities to live without access to clean water in or near their homes.

These are the strategies I used throughout the challenge:

Toilet

In Scoop, we have a policy of "if it's yellow, let it mellow" that made it pretty easy for me to use the toilets where I live. If I needed to flush, I used a bucket of water to manually flush the toilet. I obtained all of my personal-use water from a hose outside of the Greenhouses and carried it back to Scoop in 5 gallon buckets. But for the most part, I took advantage of toilets in the Science Center, Sports Center, and wherever else I found myself throughout the day.

Shower

While I tried to minimize the number of times I showered during the week, I took a couple short bucket showers in Scoop with water from the Botanic Gardens. These showers were very cold!! It took practice to figure out how much water I needed to wash all of the soap out of my hair. Once I had to turn on the shower very briefly because I ran out of bucket water. Ultimately I was able to shower with less than 2.5 gallons of water.

Laundry

Unfortunately I direly needed to do laundry during the challenge, so I lugged my laundry to McAfee and used the washer there.

Drinking water

The water I obtained from the Botanic Gardens hose was not potable, so I kept my water bottle attached to my hip all week, and filled it up in various buildings on campus throughout the day. I used this water to brush my teeth.

Hand-washing

I kept two half gallon milk bottles of water in the Scoop bathroom for washing my hands. Not having access to the sink forced me to use less water and soap while washing so that I wouldn't have to go fetch more water as often.

Scoop Chores

Since I live in a cooperative, I am not on the meal plan and have to do chores for the co-op such as washing dishes and cooking. When I washed my personal dishes I used water that I kept in a bucket in the kitchen, or I put my dishes in the dishwasher (but didn't turn it on). When I had to wash up after Scoop dinner, I would use sink water to clean big pots and dishes, and I would turn on the dishwasher. When cooking for Scoop I also used filtered sink water because I didn't want to use non-potable water in anything that people would be consuming. I felt that my responsibility to the co-op warranted me breaking the water challenge rules for the well-being of my fellow Scoopies.

Reflection

This challenge was an incredibly value experience because it compelled me to be so much more intentional about my water consumption. There were so many times during the week that I reached to turn on the faucet and then had to check myself, because I have deeply ingrained habits derived from always having had access to running water. Throughout the week, I kept a detailed journal of every time I used water, where I used it, and how much I used because I wanted to actually see how much water I was consuming. Recording my water use caused me to use increasingly less water as I realized that some of my water use (as when I take a shower that's more than 5 minutes long) is really unnecessary and wasteful.

Having to venture outside of Scoop for water forced me to structure time for water collecting into my daily schedule, which was surprisingly difficult to do even though the Science Center and Botanic Gardens are a 2 minute walk away. Often times I would forget (or be too lazy) to refill my water buckets during the day, and then I would want water for a shower or to brush my teeth in the evening, and I would have none left. This laziness left me in uncomfortable situations of having to stumble to the Botanic Gardens late at night or in the very early morning in the cold to obtain water for a much needed shower.

This very physical experience of having to carry heavy buckets of water to my dorm helped me to understand, in some very, very small and limited way, the massive challenges that people, mostly women and girls, in developing nations experience in having to walk ridiculous distances (an average of ~ 3.5 miles) to gather water for their families everyday. I only had to walk a laughable two minutes to obtain water, and I often found this burdensome. I cannot imagine having to budget hours for collecting water everyday - it would certainly limit what I could accomplish in a given day, and indeed, it significantly confines what women and girls in developing nations are able to achieve. For instance, many girls do not even have the opportunity to go to school because they are responsible for collecting water for their families.

After my water thrifty week, it seemed somehow wrong to be able to wake up this morning, and go into the bathroom and turn the faucet to wash my hands. It felt too easy, too mindless. With that one motion I felt that I had lost the connection to water that I have built in the past week from having to be so intentional and sparing with it. Once again water is an ever-plentiful, available resource in my life. Though the water challenge is over, I will try to hold onto the mindset of using water sparingly and intentionally and also, respecting water for how valuable and essential it is.

WaterWear Backpack: Benefits & Limitations

Our class experiment in which we carried water with technologies commonly used in developing nations, including the trump line, Q-drum, and traditional head carry method, helped me understand how physically taxing it is to transport water over even short distances. During the water carrying experiment, my head, arms, neck, and lower back all ached. I found myself wishing that there was a product, like a backpack, that would allow me to carry water on my back, thereby reducing the physical strain on my body.

WaterWear, a product developed by Greif and Impact Economics, draws on this exact idea. WaterWear is a collapsable backpack intended to reduce the physical burden of carrying water, while offering a safe alternative to unsafe, contaminated water containers. I see many pros and cons to this technology.

Pros:

- Collapsable (can be shipped in large quantities)

- Removable liner for easy cleaning

- Adjustable straps

- Reduces burden on head, neck and arms (distributes weight more evenly)

- Protected spout to keep water clean

- Allows for free hands

- Allows for faster movement

- Don't need help to use 

- Could wear on front or back

Cons:

- Somewhat expensive (~ $10?)

- Non-local materials (polypropylene)

- Burden on upper back

- Can only hold 5.3 US gallons

It appears that the pros of the WaterWear pack outweigh the cons that I have identified. I see the most important pros of this product to be its collapsibility, as compared to other bulky devices like the Hippo Roller, the reduced burden on the head, neck, and arms, and the ability to clean it easily, unlike the Q-drum that is virtually impossible to clean. 

My first concern with the WaterWear pack is that it expensive and is constructed from materials that cannot be sourced by the underserved communities that would receive this technology. Thus, these communities would be indefinitely reliant on the manufacturer for this product. Though the backpack costs about $10, I do not have a good conception of whether this is a price that impoverished individuals would be willing or able to pay for this technology. Compared to other items we have discussed, like the d.light Solar Lantern that costs ~$20, $10 does not seem totally unreasonable. Lastly, while I believe that this pack would likely reduce neck pain in individuals accustomed to carrying water on their heads, I think this pack could potentially be improved by splitting the pack into two smaller bags, one for the front and the other for the back. This system would more evenly distribute weight across the body, so the carrier wouldn't need to learn forward as much, a posture that strains the back. 

Despite my hesitancy to proclaim the benefits of this technology, the real evidence as to whether the WaterWear pack is successful must come from testing the product in the field with real people. According to the video on the PackH2O website, testers have embraced the packs "with enthusiasm." One Kenyan woman in the video stated that the pack made carrying water easier, faster, and less painful. Thus, it does seem like this pack has great potential. I just wonder if it is possible to design a cheaper backpack with locally sourced materials. If I had $10,000 to dedicate to addressing water issues, I would direct my money to this product only after I was sure that the packs were something that the receiving community wanted, and also if I could not find another more affordable technology with the same range of benefits. 

Learn more about the WaterWear pack here.

Gravity Light Estimation

Martin Riddiford and Jim Reeves, two London-based designers, have created a neat new product, called GravityLight. It's an LED lamp that runs off of nothing but gravity - which means the only cost of the lamp is the upfront cost of buying the product, which makes this product ideal for use in underprivileged communities that rely on dangerous and expensive kerosene lamps to light their homes in the evening.

The lamp operates on a simple concept: a cable hangs down from a gear holding a plastic bag that can be filled with dirt or any other heavy material. The energy produced from the bag being pulled down is sufficient to power an LED bulb for up to 30 minutes.

To learn more about this creative device, look here.

I did some rough calculations to determine how much weight would be required to power this LED lamp for 30 minutes.

I assumed that there were 5 small LEDs in the lamp, each being 3.2 V and 20mA.

I also assumed that the lamp would be mounted about 6 ft (1.8 m) from the ground.

Here are my calculations:

Note: I made a silly unit conversion error: 33 kg actually = 72.75 lbs!

According to my calculations, approximately 33 kg or almost 73 lbs would be needed to power this LED lamp for 30 minutes, which seems like a lot of weight, but not totally unmanageable. It looks like the user of this lamp would need to be very strong to lift this weight every 30 minutes! I will be interested to see if this technology proves to be viable in the communities it is intended for. 

UN Human Development Report 2006, Beyond scarcity: Power, poverty, and the global water crisis Response

Reading the UN water report helped me put my excessive water consumption into perspective. Though water scarcity is unheard of in my native New Hampshire, 1.4 billion people live without dependable access to clean water and 1/3 of the global population lacks access to basic sanitation. Lack of access to these basic needs is a violation of human rights, and improving access must become a global priority if we are to improve livelihoods and undo the deep inequalities that divide countries and people.

Though I’m familiar with issues of resource scarcity, I was somewhat surprised to read that the UNDP sees poverty, inequality, and water mismanagement as the causes of water scarcity, rather than a global shortage of water supply. This means that providing clean water and sanitation to the global population is possible. But the report points to a couple key reasons why this water crisis persists.

First, it is a crisis of marginalized populations: water issues are invisible to the international community because of insufficient awareness and the scale of the problem. While inadequate water access is debilitating and often deadly, "unlike wars and natural disasters, the global crisis in water does not make media headlines … Like hunger, deprivation in access to water is a silent crisis experienced by the poor and tolerated by those with the re- sources, the technology and the political power to end it." When one considers the excessive, careless use of water in rich countries, it should seem unsurprising that wealthy nations overlook water poverty.

Secondly, there's inadequate political will to address the crisis. It would cost $10 billion USD a year to meet MDG’s and significantly improve water access and sanitation globally. This price seems like absolutely nothing when you consider that the governments of the world spend that on military expenses every 8 days! This was the most shocking statistic of the report for me, and I think it illustrates the severely distorted priorities of governments. And, while the water and sanitation crisis is most sorely experienced by the poor, and women and children in particular, these groups lack the political clout to set national priorities. A surge of progressive national polices, backed by international support, is essential. I believe that community-government partnerships, in which a government provides funds and conditions for local grassroots community groups to implement locally specific solutions, can be a powerful model for change.

It is clear that women and children suffer disproportionately from water scarcity and inadequate sanitation. Women spend tons of time collecting and transporting water in water-scarce areas. I was floored to read that "40 billion hours a year are spent collecting water in Sub-Saharan Africa - a year's labor for the entire work-force in France." This is time that women could otherwise spend generating an income, or caring for their children. Inadequate sanitation also constrains the opportunities of children, especially girls. Diarrhea kills 1 child every 3 minutes, making it the #2 cause of death in children. Also, the educational opportunities of girls are constrained by lack of water access, as girls are often burdened with fetching water for their families over long distances. Furthermore, due to inadequate hygiene and privacy in school bathrooms, many girls are withdrawn from school once they reach puberty. Thus, water poverty and inadequate sanitation are viciously reinforcing gender inequalities in underprivileged communities.

It strikes me that improving water and sanitation issues would serve to advance all of the Millennium Development Goals, especially reducing child mortality, promoting gender equality, and increasing environmental sustainability.

Designing & Building a Sharps Container

The practical need for a sharps container for our lab provided our first opportunity to engage with the engineering design process as a team. Our container would serve as a safe receptacle for disposable sharp objects, such as old utility knife blades, that we would generate in the lab. Once the container was full, it would be thrown away into the Wellesley waste stream. Thus, our container needed to be sturdy enough so that the sharps could not puncture through it and harm anyone handling the container or the trash in the future. Our pool of materials was confined to materials we could find in the lab - namely, cardboard, styrofoam, and hot glue.

Before my team began brainstorming, we decided that we wanted our container to be built from less environmentally harmful materials. This criteria immediately ruled out styrofoam. We instead chose cardboard as our material of choice. Cardboard is a thick and rigged material, which would give our container a stable structure that can not be easily punctured by the sharps. And, as the college generates a massive amount of cardboard waste, it would be easy to build more sharps containers once our container became full and was thrown out.

During our brainstorming session we came up with several designs, some of which were quite silly. Our main concern in developing a design was ensuring that the box could be handled safely, so we settled on a "double box design." This consisted of a smaller box with a slot to drop the sharps in, with a cover over the slot. This small box would be suspended in an outer box on L-shaped supports attached to the top and bottom of the outer box. This idea of this design was that if a sharp was to puncture through the inner box, it would still be contained in the outer box, and would not injure the person moving the box. While a new inner box would have to be made after the first one filled up, the outer box would be reusable.

Quick birds-eye sketch of our sharps container

We estimated that the sharps box didn't need to be particularly large, as we did not expect our class of 18 people to dispose of that many sharps during the semester, and the sharps are quite small. Assuming that every member of the class threw out 3 utility knife sharps, an inner box with dimensions of 4 x 4 x 3.25 in would still have plenty of space inside.

Constructing the sharps container was quite simple, but our design changed significantly as we worked. We began by constructing the small box. We first cut out six cardboard squares, which we planned to glue together. We even traced the the corners where the cardboard supports would go, and cut out the supports.

After doing all of this, we realized that tracing out the unfolded box design onto cardboard and then cutting it out as one piece would be faster, easier, and make a more structurally sound box, so we started over. We then folded the cardboard at the lines that we had drawn, and glued the seams.

 

After our small box was constructed, we realized that it was quite sturdy and we decided that constructing a second outer box was unnecessary. We felt confident that the sharps would not puncture through the cardboard, however, we did worry about the safety hazard in the unlikely event that our box got wet.

Our last step was to cut a slit in the top of the box, and then create a cover for it so that the sharps would not escape from the box. We created a cover by cutting out a small square of cardboard and attaching pieces of velcro to the cover and to each side of the slot.

Lastly, to make our sharps box easily distinguishable from the rest of the items in our lab, we painted the box with bright colors!