Efficiency Predictions

Generating electricity with pedaling is the most efficient way to utilize pedal power.  However, with the technology that we currently have, a large amount of energy is wasted because the process is very inefficient. Energy is lost in a variety of locations: in the battery, the battery management system, other electronic parts, and the generator. 10% to 35% is lost in the battery, 10% to 20% is lost in the generator, and 5% to 15% is lost in the converter, and about 25% is lost in the regulator. Getting a better efficiency out of these parts requires better, more expensive models. This totals to about 40 to 60 percent lost. Additionally, it is important to recognize that the some of the charge will be lost if the battery stands still over time, and the battery will deteriorate over time.

Climate Change

In 2018, the United Nations released a climate report in which they stated that climate change will likely turn dangerous unless new technologies are rapidly invented that can help remove greenhouse gases from the atmosphere. To prevent the warming of the Earth by even 1.5 degrees Celsius would require an unprecedented change in behaviors. By 2030, carbon emissions would have to be cut 50%, and by 2050, the entire world would have to be carbon neutral.

In the United States, the average amount of carbon released per person per year was 20 metric tons, which comes from a variety of sources. On average, each person used 6917.4 kgoe, which describes energy use in terms of how much energy can be extracted by a certain number of kilograms of oil. 6917.4 kgoe roughly equates to 80449.362 kWh of energy. To put that in context, an LED light-bulb uses approximately 20 kWh per year

At Durham Academy, the weight room always contains several students and faculty working out on one of the many machines. Installing a self-powering bike would certainly be heavily used.

Pedaling a bike at a moderate to fast pace yields approximately 100 Watts of power. If the bike was used for 8 hours every day for 30 days, then 24 kWh of electricity would be generated. However, due to constraints with storage and energy transport, the actual amount of viable energy drops to approximately 16 kWh. To put that in context, that amount of energy is only 0.020% of the average amount of energy that a house requires. However, a phone only requires 1 kWh of charging for a full year, an hour of biking ought to be able to charge the phone.

Generators vs. Motors 12/9/18

A question that came up in my research was the difference between a generator and a motor. I saw various references to both and was wondering if they referred to the same item or different ones. A generator converts mechanical energy into electric energy to be stored or used later, whereas a motor takes electric energy and converts it into mechanical energy. This subtle difference actually makes a huge difference, and highlights the change in what I’ve been studying through the course of this semester. The original electric bike was going to use a motor to power the wheels, whereas this new electric bike is going to use mechanical energy to power something else.

As I said in my last post, a generator is something that converts from mechanical to electrical energy. An important distinction to make is that the generator doesn’t create brand new electricity to be used, rather it uses mechanical energy and converts it to electrical energy by forcing the electrons in a wire to move and create a constant flow of electrons, which is all electrical energy is. Typically, a generator uses a wire of electrons and moves it through a magnetic field. This creates a voltage difference between the two opposing ends of the wire, thus forcing the electrons to move.

A motor takes in electricity through one end, and makes an axle move on the far end. The moving axle is what allows many machines to be powered, and it would have powered an electric bike.

How It Works // Stats 12/9/18

I’ve been looking at many sites about using bikes to generate electricity, and there does not seem to be a clear-cut answer as to how much electricity they’ll generate. For example, Daily Mail UK suggested that one hour of biking will create enough energy to power a battery for 24 hours. This conflicts with reports from NPR, which says that biking for 8 hours a day for 30 days (no weekends off) only provides the average American with 2.4% of their energy needs (not including large appliances such as the dryer, refrigerator etc…). While there might be differences in the type of bicycle and the intensity with which one rides it, these numbers are extremely different.

The self-generating electric bike works when someone pedals, the wheel on the bicycle turns a flywheel, which in turn, turns a generator. The generator then can be charged into a battery, enabling the power useable. That being said, this design does mean that there are some potential areas that the bike can lose power. The efficiency is not superb because electricity can be lost to heat through the process of turning the flywheel and then transferring between the generator and the battery.

A generator, in short, is a device that converts mechanical energy into electrical energy. Mechanical energy is the sum of the kinetic and potential energy of an object, which is basically just the energy of an object due to position and/or motion. For the bike, most of the energy is going to come from the motion of the bike’s wheels. As the bike is on the ground, there is little to no effect of potential energy that the bike can use.

New Directions

Because of funding issues, it would be much more practical to continue the independent study in relation to sustainability. On average, the upper quartile of American citizens use the consume the most resources on a daily basis than anyone else in the world. DA falls into this category of these people. I’m going to apply my previous research to providing energy generation to DA using cleaner energy sources. One of the best (and easiest ways) to do this would be to produce electricity from the weight rooms. There are numerous machines with cyclic motion and it would be interesting to see how much energy they can produce.

I’m beginning the preliminary research with how much energy can be produced by one bike. The general consensus is that a person can produce 50 – 150 Watts of energy per bike per hour, which is not a lot of energy that can be gained. If there were ten bikes with everyone riding at similar effort for a half hour, then almost 500W could be generated. This can power smaller devices like a cell phone or laptop. It’s not a ton of energy, but the most important thing, however, is that the energy is completely clean and a monitor showing the energy totals would inspire more to work harder in the gym to produce more energy.

Generally, how the expensive “market” bicycles work is that they have an internal generator that produces low-power AC electricity on when the bike goes into motion. Then, the pedaling motion allows the energy to be converted to a higher level and into DC current. The energy that’s available after what’s required to power the bike can go back into the power grid. This energy total is about 74% of what was originally produced, which is a fairly high efficiency.


Updates 11/27/18

I learned something new today. I thought my bike had a ten inch radius, which would mean a twenty inch diameter for the tire. However, I actually have to measure from the center to the outer part of the tire, including the rubber on the wheel. I remeasured and realized that the entire part of the bike measured to 26″ in diameter, which would make a big difference in the kit I buy. As the kits come with a tire, it has to match perfectly with the one that exists on the bike already for the smoothest ride. As a result, I’ve had to adjust my kit order slightly. Here’s the one I’m intending to purchase:


with the following battery:



So–I’ve finally landed on a kit that I believe will be good. The battery is still being finalized, but they can be purchased separately, which should happen by the end of this week should everything go to plan.

I originally had thought that this step would take significantly less time, but my parents have been away, so it’s been harder to meet and discuss ways in which these parts can be purchased as well as getting the bike to school. This bump in the road seems to have passed, however, and hopefully more will go to plan…

Quarter One Reflections

I wasn’t really aware of how much of an undertaking this project would be. Obviously, I knew it would span a semester long, but I thought that there would be less to know. The amount of research that I’ve had to do has been long and tedious. A lot of it is not something that I can just record, so it’s been tricky documenting how much time I’ve actually spent researching and what I’ve tangibly learned from it. In some cases it’s just a little mental note that I make to myself that’s just like ‘hey, that person did this, don’t do that because their bike doesn’t work now’.
In September, I found it hard to get going on the project because I didn’t really even know where to start, so there was a lot of procrastination there. However, after we began to meet, it started to go better and I’ve been much more diligent about what I need to do and what I get done in terms of research. There are also people at DA that I’ve learned have done similar builds before, so I’ve been using them as a resource too.
I thought I’d be building in October, but the research was significantly more than I was anticipating…but I think we should start next week. 🙂

Weekly Update

The Hurricane set me behind by a few days, but I’ve been researching about bike/battery combinations on Amazon. The most tedious part of this process is figuring out which batteries work with which motors and then which set isn’t remarkably expensive or poorly reviewed. I have a couple in mind that are my best hope for a middle ground and hopefully, I’ll be able to get those ordered soon!