The Human Power Plant is a working prototype of a muscular power generator, manned by a group of people. We cooperated with makers and sports coaches to build exercise machines that are suited for different types of human power sources, are fun and social to use, and produce a maximum amount of power.
The Human Power Plant is an all-round off-the-grid solution. It can supply energy anywhere and anytime, provided that humans can be motivated to operate it. The power plant supplies energy in the form of electricity, water under pressure, and compressed air. It is built from simple and durable parts.
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These days, we have automated and motorised even the smallest physical efforts. At the same time, in order to keep in shape and stay healthy, we go to the gym to workout, generating energy that's wasted. The Human Power Plant restores the connection between physical exercise and energy use.
Lessons from the Gym
During the research phase, we followed a fitness programme to become better human power sources. This was a very instructive experience. One of the first things we learned is that there are important differences between individuals.
Melle, the powerhouse in our team, could lift a heavier weight on almost any machine. Kris, on the other hand, appeared to have better endurance, and could beat Melle with triceps and shoulder exercises. Such differences should be taken into account in order to achieve optimal energy production - there is no ready-made solution.
We also discovered that exercise machines for strength training can produce a lot of power in a very short time, making them an interesting addition to stationary cycling machines for human power production. Because most of them work on the basis of lifting weights, their power potential can be calculated.
Another thing we learned is that gyms are pretty boring places. The fitness equipment is positioned in such a way that people look in the same direction, which excludes all communication. And, while a stationary bicycle is considered to be the most energy-efficient human power machine, we discovered that stationary cycling is no fun.
For the design of our Human Power Plant, we wanted to address these issues.
Hydraulic-Pneumatic System
The human power plant consists of several exercise machines, which are set up around an energy storage and regulating device. Roughly half of the exercise machines are pumping water into a pressure vessel, while the other half are pumping air into a smaller tank.
The air from the smaller vessel then compresses the water in the larger one, increasing the energy potential of the hydro-pneumatic accumulator (small + large tank).
Next, water under pressure is led to a Pelton wheel, which can supply mechanical energy or electricity (if coupled to a generator). The water falls from the water turbine into a receiving reservoir, from where it can be pumped into the accumulator again.
Human Powered Jacuzzi
The receiving reservoir of this closed water system is converted into a shower/jacuzzi, where power producers can cool down and relax after their effort.
The electricity produced by the Pelton turbine can be used to heat the water of the jacuzzi, while compressed air can generate bubbles and water under pressure can produce water jets.
A Sustainable Battery
We opted for water under pressure and compressed air for several reasons. First, we want to make energy more visible and audible. Electricity is used all around us, but these energy flows are quiet and invisible. If we want to focus on energy, we first need to be aware of it.
Second, water and air allow us to produce electricity without the use of chemical batteries and electronics -- which are not sustainable components. In our muscular power generator, the hydro-pneumatic accumulator takes over the role of the battery and the voltage regulator.
In this way, small variations in human power production can be smoothed out, keeping the voltage constant. Longer term energy storage is supplied by the humans themselves. Unlike solar and wind energy, human power is always available.
The human power plant is built from simple and mostly scavenged parts. The machine can be maintained and repaired by a plumber. Unlike chemical batteries, which need to be replaced every few years, the human power plant can be operated for decades.
The human power plant is a work in progress. Each time the contraption is moved to another location, we improve, adapt or replace exercise machines.
Human Power Plant 1.1: Exercise Machines
The machines described below concern the set-up in Deventer, the Netherlands, where the human power plant was exhibited in July/August 2017
1. Reverse Hack Squat
The Reverse Hack Squat is aimed at strength training. A person stands with curved knees below the bar and stretches his or her legs. The exercise mainly builds leg muscles and strengthens the bones and the tendons.
This exercise machine converts human power into compressed air, which is used to pressurise water. The machine also produces a wonderful sound.
Our legs are roughly four times stronger than our arms, and this exercise machine is our most powerful producer of compressed air. The effort that's required to lift the bar increases as the pressure vessel fills up.
2. The Cross Trainer
The Cross Trainer is the archetypal exercise machine, aimed at endurance training. The exercise strengthens the heart and the lungs.
Almost all the muscles are used, but the load on the body is the heaviest on the legs and the shoulders. The muscles of the torso are also used, especially for maintaining stability.
The arms push the levers forward and backward. This movement pumps water into the pressure vessel. The legs are moved up and down as if walking up the stairs. This movement is pumping air into the pressure vessel.
Arms and legs are moving at the same time, somewhat similar to the movements during cross-country skiing. Two people can operate the machine while looking at each other, which creates an intimate atmosphere. The machine makes a lot of noise.
3. Biceps and Triceps Extension
This exercise machine, which produces compressed air, can be operated by four people simultaneously.
One person operates the foot pedals, which work similar to the foot pedals of the Cross Trainer that we described above. Two persons train their biceps and triceps by moving the handles on each side up and down.
A fourth person turns the wooden wheel that operates an air compressor. The latter produces delicious farting sounds and is very popular with children and adults who refuse to grow up.
The manually operated air compressor is surprisingly effective. We aim to improve it further by adding a better flywheel that is turned by a smaller hand cranked wheel.
4. Heavy Pull Drag
The Heavy Pull Drag produces a large amount of power in a short time. The machine is inspired by human drawn canal boats from earlier times. As an exercise device, it appeared in the 1990s, aimed at American football players.
To produce power, the operator puts on a harness with a cable attached to it. The cable is wound around an old car rim, which is fixed to a powerful membrane pump.
The operator walks forward or backward while wearing the harness, keeping his/her body as low to the ground as possible. Walking forward trains the muscles in the back, walking backward trains the quadriceps in the legs, and pulling sidewards trains the muscles of the hip.
The Heavy Pull Drag is our most powerful water pump. Although it works very well, it needs some further improvements. The most important one is a mechanism that rolls the cable in automatically.
Human Power Plant 1.2: Work Songs
Video of the prototype in Antwerp. Made by Laura Zuallaert.
In order to try and motivate people to generate their own power, we have equipped the second version of our human power plant with sound production.
In earlier times, when physical labour was much more common than it is today in the industrialised world, people sang songs to increase work productivity, keep boredom at bay, or coordinate the actions of different workers. At the same time, these work songs were an outlet for humour, ridicule, and frustration.
Following the same logic, in the Human Power Plant every movement that produces energy now also produces sound. Consequently, each time the Human Power Plant is operated, a work song is composed.
The Human Power Plant 1.2 was built in Antwerp, Belgium, where it was shown during a preview on October 8, 2017. Archipel, the makers collective that offered us the space, brought a team of unsuspecting bodybuilders to the event and made a video, which you can see above.
Prototype in Antwerp. Picture: Alies Broekhuizen.
From October 14, 2017 to January 15, 2018, the Human Power Plant can be seen, touched and operated at the Museum Boijmans van Beuningen in Rotterdam. It will power the Christmas tree of the museum, provided that visitors are prepared to exercise
The Boijmans Museum made a video of us while we were building the Human Power Plant in Antwerp, which you can see below.
During the first month in Rotterdam, sound production has already proven to be a very effective motivator of human power, even without a tree to light up. In fact, the human power plant has become the victim of its own success, needing daily repair to keep it in operation.
In comparison with our previous prototype, which tried to lure people with a jacuzzi, it is clear that sound attracts more energy producers and keeps them exercising for longer.
The Human Power Plant in Museum Boijmans, Rotterdam. Pictures: Aad Hoogendoorn.
How Much Energy Does it Produce?
Some people have asked us how much energy the human power plant produces. The answer is: not much. This prototype was built to investigate whether or not people can be motivated to produce their own power, and do this in the most sustainable way (no chemical batteries, no high-tech components).
To achieve this, we built a very energy inefficient power plant. Everything that makes it fun, also makes it inefficient. Take another look at the scheme below. Mechanical movement is converted to water under pressure and compressed air, which are then converted to electricity.
There are so many conversion and distribution losses in the process that it's actually surprising that the human power plant still generates electricity at all -- an estimated 60 watts of power when all six exercise machines are used simultaneously. Assuming an average human power production of 100 watts, this corresponds to 10 watts of power per person, or an energy loss of 90%.
Could it be that efficiency is simply not fun? Or could we make a human power plant that is both energy efficient and fun to use? That´s the challenge for the next prototype.