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Pedal powered farms and factories: the forgotten future of the stationary bicycle

If we boost the research on pedal powered technology - trying to make up for seven decades of lost opportunities - and steer

it in the right direction, pedals and cranks could make an important contribution to running a post-carbon society that

maintains many of the comforts of a modern life. The possibilities of pedal power largely exceed the use of the bicycle.

One way to solve the large energy losses of pedal power generators is not to produce electricity at all but power devices

mechanically, whenever possible. Another way - the only way for devices that cannot be powered via a direct mechanical

connection because they do not rely on rotary motion - is to make the generation of electricity more efficient. This can be

done by building a pedal powered generator from scratch instead of using a road bicycle, or by ditching one or several

electronic components in the power transmission chain. All approaches can be combined, resulting in a pedal power unit

that can power a multitude of mechanical devices and generate electricity comparatively efficiently.

Direct Mechanical Power Transmission

Many machines could be powered by a direct mechanical connection, though it generally means adapting the device so that

it can work independently of electricity. However, stationary pedal machines with direct mechanical power transmission -

although they were common in the old days - are not available commercially in the western world.

LOW-TECH MAGAZINE: Pedal powered farms and factories: the forgo... http://www.lowtechmagazine.com/2011/05/pedal-powered-farms-and-fac...

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The only exception seems to be the Fender Blender, a pedal powered

machine used to make smoothies (picture on the right). However,

old school bicycle machines are now being designed both by

amateurs in the western world and non-profit organisations in the

developing world.

In Guatemala, Mayapedal has been building some 2,000 pedal

powered machines from old bicycle parts since 2001. To date, the

NGO has built pedal powered water pumps, grinders, threshers, tile

makers, nut shellers, washing machines and blenders. These cost

only $40 to $250 to make. Their contraptions have become more

sophisticated and even cheaper to build over time, evolving from

adapted bicycles to pedal powered machines built from scratch

which incorporate a flywheel, and are capable of driving different types of appliances.

Another example is the VitaGoat Cycle Grinder developed by the Canadian NGO Malnutrition Matters. The pedal powered

grinder forms part of a complete food processing system which is delivered to developing countries in Asia and Africa.

Chocosol teaches local people in Mexico to build their own pedal powered cacao bean grinders and the Canadian promoters

also use the technology in their shop in Toronto. The Full Belly Project designs human powered nut shellers for farmers in

Africa.

Then there are the many contraptions

built by individuals too: the pedal

powered washing machines by Alex

Gadsden and Homeless Dave, the

pedal powered soap blender by

Frederick Breeden, or the pedal

powered apple grinder by Ben Polito.

Similar machines have also been built

outside the US. Some have

concentrated on restoring and putting

to use antique machines, like Blue Ox

Millworks.

One obvious disadvantage of

designing a pedal powered machine

for every application in the household,

farm or workshop is that you need a

lot of space. Furthermore, designing a

pedal power unit for every tool might

become labour-intensive, costly and

energy-intensive.

This is not as much of a problem in

cases of small-scale industrial use,

where few machines are required in

order to manufacture a product. A good example of this is the pedal powered soap blender mentioned above. For this

reason, a pedal powered blender could be a realistic option for small businesses, such as a smoothie bar. However, when

more tools are needed and space is restricted, as is often the case, we need to find ways to get around this problem. One

solution is to use pedal power to generate electricity which can then be used to power different devices. However, this

approach is highly inefficient with energy losses of up to more than 70 percent and should be avoided whenever a device can

be powered in a mechanical way.


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The design of universal pedal powered units with direct mechanical transmission was

extensively researched in the 1970s

Another solution is to design a universal pedal power unit with direct mechanical transmission that can be used to operate a

large variety of different tools and devices (including a generator). This method, which solves both the space and inefficiency

problem, was extensively researched in the 1970s.

Multi-purpose Pedal Powered Machines

Universal pedal powered machines did not exist at the turn of the twentieth

century, although some combined a few functions (both sawing and drilling, for

instance). At least five interesting inventions were designed and built in the

1970s: the Energy Cycle (by Dirk Ott), the Dynapod (by Alex Weir), the Human

Powered Flywheel Motor (by JP Modak), the Pedal Power Unit (by David

Weightman) and the Dual-Purpose Bicycle (by Job Ebenezer). All these concepts

are also of interest for the construction of single-purpose pedal power units.

The Dynapod

After experimenting with single-purpose pedal powered machines in several countries in Africa, British engineer Alex Weir

(who is also the promoter of this online low-tech database) built a multi-purpose 'Dynapod' (the name stemming from the

Greek words for 'power' and 'foot') in Tanzania in the early 1970s. The power module, based on a 1968 concept by Stuart

Wilson of Oxford University, came in a one-man and two-man version. The tandem unit doubled the power output, and at

the same time evened out the power flow, with both sets of pedals placed out of phase.

The Dynapod was made using a custom-built frame. Apart from

pedals, cranks and chain drives, the machine shared nothing with a

bicycle. The first designs used wooden frames, while later versions

were based on a steel frame. For a flywheel, Weir used an old bicycle

wheel filled with cement. The cost of the wooden frame unit (in

1980) was $40 to $100, materials and labour included.

The Dynapod could drive pumps, corn grinders, winnowing

machines, forge blowers, grinding machines, drilling machines,

potter's wheels, paint sprayers, crop dusting equipment, cassave

graters, coffee pulpers, grain hullers, fibre decorticators, threshers,

balers, band saws, tire pumps and sewing machines. It could also be

used to generate electricity.

Apart from pedals, cranks and chain drives, these human powered machines share

nothing with a bicycle

To allow the operation of such a wide diversity of appliances, the Dynapod was equipped with multiple drives. It could be

operated with a direct drive having a ratio of 1:1 (when a lot of torque was needed at a slow speed), a chain drive with a ratio

of up to 3:1 (a compromise between torque and speed for operating grinders, threshers, etc.) or a belt drive with a ratio of up

to 10:1 (for electrical generation, a winnowing fan, and other uses where high speeds were required). The machine was easily


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adapted from one drive to another. Multiple drives on pedal powered machines were not a novelty - some earlier pedal

powered machines had them too.

The Energy Cycle

Rodale Press, the publisher of the 1977 book 'Pedal

Power in Work, Leisure and Transportation' also had a

research team - Rodale's Research and Development

Department. Together with inventor Dick Ott they

conceived their version of a universal pedal power unit,

the 'Energy Cycle'.

Just like the Dynapod, it was built from scratch and

could accommodate a large number of detachable

tools. These included kitchen aids (such as an egg

beater, can opener, nut chopper, food grinder, fish

skinner, meat and cheese slicer and a cherry pitter),

farm machinery (including an irrigation water pump,

feather plucker, potato digger, corn sheller, grain

cleaner, rice polisher and oatmeal roller) and more

general tools (like a wheel grinder, stone polisher, drill,

wood carver and battery charger).

Several improved prototypes were built, first of iron,

and then of steel. For the first upgrade of the design, a

large work table was added to the unit which enabled

the operator to perform numerous tasks without

leaving his seat. Later versions were equipped with a

flywheel. Experiments showed that the unit offered

considerable benefits in comparison with hand

powered machines or small horse power motors and

engines. The main challenge remains in finding a

universal means of attaching each implement to the

Energy Cycle - which should be easily overcome if

serious industrial research is dedicated to it.

Pedal Powered Winch: Substituting a Farm Horse or Tractor

Both the Dynapod and the Energy Cycle could also double up as a pedal powered winch,

offering a whole new array of possibilities. A winch is useful for pulling, excavating, load

lifting, or snow plowing. In agriculture, a winch can be utilized for cable-cultivation, a

principle in which the motive power for plowing (or harrowing, cultivating, seeding and

hay raking) is stationary and only the tool (attached to a multifunctional mobile tool

carrier) moves across the field along a cable.

This agricultural method is based on steam cable plowing, which was the only

mechanized method of agriculture for almost one hundred years. Cable-cultivation brings

considerable savings in energy, because the motive power - be it human, animal or

mechanical - does not have to waste power in moving itself over the soil. Additional

advantages are the avoidance of soil compaction, a notable drawback of using a tractor,

and the possibility to work on waterlogged ground and steep slopes.


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Cable-cultivation is a principle in which the motive power for plowing (or harrowing,

cultivating, seeding and hay raking) is stationary and only the tool moves across the

field along a cable.

In a field left fallow for a year, the Energy Cycle pulled a plough through the grass and weed covered

soil, successfully substituting the work of a farm horse or tractor. One person pedalled the winch that

drew the plough through the soil while another guided it. It took the two presons about an hour to plow

1,500 square feet. The only difficulty was that the winch had the tendency to break or bend ordinary

hand tools. Because of this problem, and because the Energy Cycle held so much promise as a garden

and farm tool, the research team built a specialized pedal powered winch and special tools to be used

with it.

This more compact unit - basically two pedals separated by a spool mounted on bearings, built into a

frame which also supports the seat - was capable of pulling over 1000 lbs (453 kg) with average pedalling effort, amplifying

human power by almost ten times. Together with a specially designed frame that could hold different attachments, it was

successfully used for pulling, snow plowing, dislodging small stumps and pulling seeders, harrows and hay rakes.

Low gears were used for jobs requiring a slow, powerful pull, such as plowing through heavy soil. Second or high gears were

used for easier jobs such as harrowing or cultivating. In order to be moved sideways so as to easily cultivate one row after the

other, a pedal powered winch can be mounted on skids. The weight of the operator provides sufficient anchorage while in

use.

Human Powered Flywheel Motor

An interesting variation on the multi-purpose pedal powered machine is the Human Powered Flywheel Motor (pdf)

designed by J.P. Modak, an emeritus engineering professor from India. The remarkable feature of Modak's machine - which

has been developed since 1979 - is that it can deliver much more power than the human who operates it.

The human powered flywheel motor can deliver much more power than

the person who operates it


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The machine system uses human energy and stores it in a flywheel at an energy-input rate convenient to the pedaller. After

storing the maximum possible energy in the flywheel (pedalling time is 1 to 2 minutes), it is made available for the actuation

of the process unit by the rapid release of the stored kinetic energy in the flywheel via a suitable clutch. The concept only

works when the process can be of intermittent nature without affecting the end product.

The human powered flywheel motor was initially developed for the making of bricks for a housing authority in Mumbai,

India. Since then, it has been successfully used for several rural-based production activities such as water lifting, algae

formation processing, wood turning, winnowing, wood strip cutting, electricity generation and the operation of a smiths

hammer. Processes needing up to 6 HP could be energised by the machine concept (although only one third of this has been

achieved to date). This would be about 20 to 60 times more than what an average human can sustain either momentarily

(300 watts) or for long periods (100 watts).

The energy unit consists of an existing bicycle frame which provides a seat and handle, a pair of speed-increasing gears, and

a flywheel of about one metre in diameter. The transmission consists of a spiral clutch and a torque-amplification gear pair.

For brick manufacturing in particular, the process unit consists of an auger, cone and die, conventionally used for motorized

brick-extruders for the manufacture of clay bricks.

Combining Stationary and Mobile Pedal Power

A very different approach to multi-purpose pedal powered machines was followed by David Weightman. His concept (and


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prototype) was inspired by the Dynapod, but Weightman added one feature: the machine should still be usable for

transportation. His Pedal Power Unit (PPU) was comprised of a bicycle wheel in forks fitted to a frame with a saddle. The

unit could then be used independently to drive machinery via a power takeoff but could also be connected to a two-wheel

chassis to form a load-carrying tricycle. Furthermore, the unit could be connected in series with other units for machine

applications requiring more power. Weightman justified his concept by emphasising the close link between transport and

machine use in agricultural and industrial production:

"In a typical agricultural growing cycle, seed and fertilizer are transported to the field, crops are grown and then

processed by machinery, and then produce is transported to the market. Similar patterns can be seen in construction

and small scale industrial production. The use of a pedal power unit in this dual purpose role is exactly analagous to the

use of tractors in European agriculture as power sources and transport devices. The PPU is equally suitable as the

Dynapod when operating a number of machines but is more economically feasible for an individual farmer due to its

capability as a transport device."

The Dual-Purpose Bicycle looks very similar to the electricity generators

which are sold today, though it is aimed at mechanically driving multiple

machines and producing electricity

Job Ebenezer from the MGO 'Technology for the Poor' further developed this design, simplifying it greatly by substituting

the tricycle for a bicycle. At first sight, his 'Dual-Purpose Bicycle' looks very similar to the electricity generating units which

are sold today, though it is aimed at mechanically driving multiple machines and producing electricity.

The ingenious design, primarily for agricultural use, consists of a very small flywheel attached to a standard bicycle, which

permits its use as a pedal-powered machine that can be utilized to power numerous small-scale mechanical devices such as

grain threshers, grinders, winnowers, peanut shellers, corn shellers, circular saws, wood working lathes, water pumps,

electrical generators, and a variety of small tools.

The contraption can be converted from the transportation mode to pedal power mode in a matter of minutes. The broad

stand, which provides stability during power production, can be flipped upward during the transport mode and doubles up

as a freight carrier. The power-generating device remains attached to the bicycle in transportation mode, so that it can be

easily transported and used immediately. Of course, this pedal power unit is a compromise, but it is an interesting one.


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Contrary to modern concepts, it has a small flywheel and it does not

use a friction drive because of its low efficiency. During the

prime-mover mode, the bike's regular chain is slipped off of the

chain-wheel, and a custom chain to the power take-off mechanism is

slipped on. Changing gear ratios is as simple as it is on a road bike.

For driving more powerful devices, a larger flywheel can be placed

between the power module and the process unit.

Treadles

The many advantages of pedal powered machines don't make hand

cranks or treadles obsolete. Not all devices need the extra torque of

pedal power. Hand cranks and treadles can be a better option if

power requirements are low or if power is only needed over a short

period. A hand cranked device is much more compact than a pedal

powered device. If hand control is required while operating low

power equipment, treadles remain the best choice because they offer

the operator more freedom of movement than pedals.

Of course, both mechanisms can also benefit from advantages in

modern design and materials - including speed or torque increasing

gears. A good example is the R2B2 kitchen unit by German designer

Christoph Thetard (which is not for sale, unfortunately). It combines

three kitchen appliances with a central driving unit. The heart of the unit is a treadle powered flywheel which works as an

short-term energy storage (as in the Human Powered Flywheel Motor), capable of delivering up to 350 watts (of mechanical

power) to the appliances. Similar to late 19th century machines, and contrary to today's kitchen devices, it is built to last.

Lowering the Costs and Energy Losses of Pedal Powered Electricity

Many modern machines and devices cannot be powered directly by mechanical energy. This is especially true for electronic

equipment (such as computers, cell phones, televisions, routers, etc.) but it is also true for refrigerators and light bulbs. If we

want to keep these modern comforts, we have to find a way to make pedal powered electricity more efficient. There are

several ways to do this.

1. Build a Generator from Scratch

Because it has few disadvantages, the best way to start is to build a pedal generator from scratch instead of using a bicycle on

a training stand. This allows you to replace the friction drive by a more efficient drive, like a chain drive, and to add a

flywheel.

Steel flywheels can be found on the most expensive exercise bicycles. However, a flywheel can also be cheap, low-tech and

just as efficient when you are using a bicycle wheel filled with concrete or a wooden tabletop. The latter is used by the 'Pedal

Powered Prime Mover' (PPPM) made by David Butcher, which is one of the few good examples of a pedal powered electricity

generator built from scratch (the plans sell for $50 and the cost for the DIY version is estimated at $230). It consists of a

steel frame made of steel shelving supports.

Although the PPPM uses a friction drive, it is a rather efficient one because it is basically powered by a wooden tyre - the

flywheel. Since higher tyre pressure increases the efficiency of a friction drive, a wooden wheel can be considered a bicycle

wheel with optimal tyre pressure. Furthermore, the flywheel is powered directly by the pedals, eliminating the energy loss in

chains and sprockets altogether (it is a 'direct drive' in other words). The only drawback of this method is that you can't

change the gear ratio.

Butcher (who built his first machine in the seventies) claims an improved efficiency of 25 to 50% compared to a standard

bicycle on a training stand. Interestingly, it can also power some devices via a direct mechanical connection: a water pump, a


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hammer, a masonry chisel, an air compressor and a hack saw.

Building a pedal powered machine from scratch can thus offer you

the best of both worlds.

2. Ditch the Electronics

You can go much further in order to improve the efficiency of a

pedal powered generator. In the most extreme case, you could skip

the voltage regulator, the converter and the battery, which leaves you

only with the energy loss of the generator. Or you can leave out

either one of these devices.

In the most extreme case, you could skip the voltage regulator, the

converter and the battery, which leaves you only with the energy loss of

the generator

However, all these actions come with a price. If you do

away with the converter, you need to replace the

electrical devices you use. What you need, then, are

DC-appliances like the ones you can plug in the interior

of your car. While this can be an interesting option

because of the high efficiency loss of a converter (25%),

not all appliances come in a DC-variant (there are no

DC-laptops, for instance*).

If you do away with the voltage regulator - and several

of the pedal powered generators come without them -

you have to carefully watch a multimeter while

pedalling to make sure that the voltage does not exceed

the capacity of the battery (or the device you are

powering if you do away with the battery too). If not,

you could destroy the battery (or the device, if you don't use a battery). A flywheel can be of great help here, because it

smooths out not only the energy input (the alternating high and low force of a natural pedalling rhythm) but also the energy

output, keeping the voltage relatively constant.

3. Get rid of the Battery


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Doing away with the battery, or replacing it with a much more efficient and robust ultracapacitator, is

probably the most rewarding thing you can do, not just in terms of efficiency, but also in terms of costs,

reliability and - especially - sustainability. (Capacitators have a much longer service life than batteries,

but a much lower energy density). However, you lose the advantage of generating energy and storing it

for later use. In this case, you would have to pedal while using the device at the same time, as is the

case with direct mechanical power transmission.

Whether or not this is convenient is dependent on what you want to use your generator for. If you

mainly want to charge your laptop or cell phone, not having a battery to store the electricity isn't a

problem since the devices themselves have a battery. However, if you want to light the staircase room

or power a television, desktop computer, electric guitar or small fridge, this becomes rather awkward. If you want to play

recorded music and dance, not using a battery would also be difficult.

4. Build large-scale Pedal Power Plants

Improving the efficiency of pedal powered electricity generation becomes easier as you organise it on a larger scale. In most

of the arts and education projects described earlier, like the BBC program or pedal powered concerts, no batteries are used.

The key here is that it is not one person both generating and consuming power, but a large group of people, of whom some

are producing electricity whilst others are consuming it.

In a similar fashion, electricity could be generated in large pedal powered electricity plants, and then distributed to houses,

shops, public spaces and factories. This is more efficient than doing it in each house separately because you can do away

with the batteries and still offer electricity 24 hours a day. Power plants would simply add more pedallers when demand is

high (such as during peaks hours) and send them home when demand is low (at night, for instance).

Pedal powered electricity plants could be a valuable backup solution to

intermittent renewable energy sources


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Human powered electricity plants should avoid the transmission losses of today's extremely centralized power network.

They should preferably be located in every neighbourhood or city district. In this scenario, it also becomes possible to do

away with converters and switch the electricity distribution system from AC to DC, since the former was only chosen

because it is more efficient to transport electricity over large distances. Of course, this is less plausible, since it means

rewiring cities and replacing all devices.

The future of Pedal Powered Machines

If we boost the research on pedal powered technology - trying to

make up for seven decades of lost opportunities - and steer it in the

right direction, pedals and cranks could make an important

contribution to running a post-carbon society that maintains many

of the comforts of a modern life. The possibilities of pedal power

therefore largely exceed the use of the bicycle.

Pedallers could power agriculture, factories, construction, mining

and even other means of transportation than bicycles: aerial

ropeways, cable trains and trolleyboats. Pedal powered electricity

plants could be a valuable backup solution to intermittent renewable

energy sources, replacing coal, gas and nuclear as a base load power

for when the sun and wind let us down. Human power is available 24

hours per day, is not affected by changes in the weather, is portable

and can easily be stored for later use. Contrary to wind and biomass,

it is an energy source that will never be depleted, since its potential

keeps pace with population growth. Pedal power would also aid unemployment, leave us with a fit and healthy workforce,

and produce a great deal of nice-looking bottoms.

The Limits of Pedal Power

Of course, pedal power can only make a difference if we drastically reduce energy consumption. While athletes can produce

a power output of over 2,000 watts on a bicycle, they can only sustain this over a period of a few seconds. The power that

can be delivered by the average person over a sustained period of time is much less impressive than that: 75 watts or 1 "hup".

This unit of measurement (short for human power) was proposed in 1984, and tells us that an average person can sustain

one hup for all day, 2 hups (150 watts) for roughly two hours, 3 hups (225 watts) for about 30 minutes and 4 hups (300

watts) only momentarily.

The absence of self-produced cooling winds results in possible

overheating of the body

Another reason not to be overly-optimistic about the energy output of stationary

pedalling is the fact that a stationary pedaller does not need to overcome air resistance.

This sounds like a good thing, because at higher speeds a cyclist spends most of his

energy compensating for air resistance. However, air resistance also keeps the active

human body from overheating.

It was found that the power output measured by ergometers (stationary bikes used to

measure the power output of cyclists) is substantially lower than that produced by the

same persons on the road because the absence of self-produced cooling winds, which

results in possible overheating of the body (this is also a problem with velomobiles). A

(self-propelled) fan could keep the stationary pedaller cool, but it is only a partial


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solution. As David Wilson notes in 'Bicycling Science':

"The relative air flow generated by cycling is of such magnitude that it bears little resemblance to the drafts produced

by the small electric fans often used for cooling people pedalling ergometers. At a speed of about 9m/s about 150 watts

are dissipated into the air. Even if cooling fans of this power level were used [negating the power production by the

pedaller, kdd], the cooling effect would be much less than that for the moving cyclist, because most of the fan power is

dissipated as air friction in areas other than around the subject's body."

While body heat production might provide interesting side-effects in winter - you and even other people in a small room

would not need heating - it would definitely limit the energy that can be delivered by pedal power. Pedalling outside when

it's windy may help, but this is not always possible.

Wanted: 1.2 billion Pedallers for the UK

The main problem, however, lies in the demand for pedallers. To give you an idea, let's see how many people would be

needed in order to use pedal power at a base load power plant. An average UK family consumes about 13 kWh of electricity

per day (an American family would consume at least twice as much). If we consider a relatively small energy loss of 25%

when converting human power to electricity, it would take 173 hours of pedalling at 100 watts (thus over one 'hup') in order

to produce 75 Wh per hour. If we presume an electricity consumption that is evenly distributed over the course of 16 hours

and no electricity consumption at night, this would take two shifts of ten people each pedalling non-stop for eight hours.

And this concerns only residential electricity use.

If we consider total electricity consumption in the UK, each person

needs 15.7 kWh per day, or two teams of ten people each pedalling

non-stop for 8 hours. The UK would have to import a workforce of

1.2 billion people (a number equal to all the inhabitants of India) to

pedal its way into energy independence, and prohibit all these people

from using electricity themselves.

Here we are not even considering peaks in demand, but average

consumption. And we are talking only about electricity consumption,

not heating and transportation fuels. Of course wind and solar could

help to diminish the need for base load pedal power. But when there

is no sun or no wind, the power would have to be supplemented.

On the Other Hand/Foot


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In other parts of the world, things are slightly different. If all Nepalese people could pedal two hours per day, the country

would be entirely pedal powered, even without the support of other renewables. Interestingly, the NGO Ecosystems Nepal

distributes pedal powered generators to Nepalese villages where they are used in a scenario somewhat similar to the one

envisioned above. A village is equipped with one pedal power generator, which is pedalled for eight hours per day, charging

large batteries.

The main problem with our approach to pedal powered machines is that we

compare them to fossil fuel powered machines and not to the inefficient human

powered tools and machines that went before them.

This village 'power plant' is then visited by the people living in the countryside in the surroundings of the village, who pass

by once a month or so to charge their small motorcycle batteries. Even taking into account the considerable energy losses (in

using batteries to charge batteries) one pedal generator provides enough electricity for 200 homes. This is possible because

small batteries only need to power 0.2 watt led-lamps, enough to read a book. I am afraid that even my Kindle uses more

than that, and it has no reading light.

Cranks and pedals are not a solution at all if we decide to cling to an energy-intensive lifestyle - but then, neither is any other

renewable (or even non-renewable) energy source. The main problem with our approach to pedal powered machines is that

we compare them to fossil fuel powered machines and not to the inefficient human powered tools and machines that went

before them. This explains why pedal power is often laughed at in the western world but enthusiastically welcomed in the

developing world, where, for instance, methods of agriculture still rely heavily on the use of human power using primitive

tools which are usually inefficient. This is a scenario in which light is produced by dirty and inefficient kerosine lamps, or

where there is no light at all.

Ironically, communities in the poorest countries in the world are developing into sustainable societies independent of fossil

fuels, enjoying basic but modern comforts, while we continue to be ever more dependent on increasingly dirty, dangerous

and diminishing energy sources.


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Kris De Decker (edited by Deva Lee)

MORE: THE SHORT HISTORY OF EARLY PEDAL POWERED MACHINES

The historical importance of pedal powered machines can be easily overlooked by people who grew

accustomed to fossil fuels and ubiquitous electricity. It cannot be stressed enough how much of an

improvement pedal power was in the light of thousands of years of human drudgery. Pedals and cranks

make use of human power in a near-optimum way. Historically, the motions used to harvest human

muscle power used inappropriate muscles moving against resistances which were too large at speeds

which were too low. Read more.

MORE: BIKE POWERED ELECTRICITY GENERATORS ARE NOT SUSTAINABLE

Pedalling a modern stationary bicycle to produce electricity might be a great work-out, but in many

cases, it is not sustainable. While humans are rather inefficient engines converting food into work, this

is not the problem we want to address here. People have to move in order to stay healthy, so we might

as well use that energy to operate machinery. The trouble is that the present approach to pedal power

results in highly inefficient machines. Read more.

MORE: FULL PLANS FOR A PEDAL POWERED JUICE EXTRACTOR

What happens when two industrial design students from Sweden end up in Kenya creating a pedal

powered machine for small-scale farmers who are often illiterate and speak more than 60 languages?

You get a do-it-yourself design that seems to have come out of the IKEA factories - pictoral manuals

included.

Sources (in order of importance)

"Pedal Power in Work, Leisure and Transportation", edited by James McCullagh, Rodale Press, 1977. Still the best

resource on pedal powered machines.

"The Human-Powered Home: Choosing Muscles Over Motors", Tamara Dean, New Society Publishers, 2008. Very good

book on human powered machines, both hand and foot powered. Includes half a dozen plans to convert bicycles into

stationary pedal powered machines.

"Bicycling Science", Third Edition, David Gordon Wilson, 2004

"The Dynapod: a pedal power unit" (pdf), Alex Weir, 1980. More here.

"The use of pedal power for agriculture and transport in developing countries" (pdf), David Weightman, Lanchester

Polytechnic, 1976

"Design of a human-powered utility vehicle for developing communities", Timothy J. Cyders, 2008

"Supplement, Energy for rural development", National Research Council, 1981

"Tales from the Blue Ox ", Dan Brett, 2003

"Bicycles and tricycles", Archibald Sharp, 1896

"In search of the massless flywheel" (pdf), John S. Allen, Human Power (Fall/Winter 1991-1992)


14 of 24 5/13/2014 12:33 PM

"Design and development of a human-powered machine for the manufacture of lime-flyash-sand bricks", J.P.Modak &

S.D.Moghe, Human Power (Spring 1998)

"Human Powered Flywheel Motor: concept, design, dynamics and applications", J.P.Modak, 2007

"Modern mechanism: exhibiting the latest progress in machines, motors, and the transmission of power", Benjamin

Park, 1892

"Make electricity while you exercise", Mother Earth News, 2008

"Luther's tool grinders" (pdf, 5.8 MB), hand and foot powered grinders catalog. Hosted at Toolemera Blog.

"Woodworkers' tools and machines" (pdf, 29 MB), product catalogue no.25, 1884, Richard Melhuish Ltd., Tool and

Machine Merchants, London. Hosted at Toolemera Blog.

"Science & civilisation in China, Vol.5, Part 9", Joseph Needham, 1988

Related articles:

How to make everything ourselves: open modular hardware

The mechanical transmission of power (1): Stangenkunst

The mechanical transmission of power (2): jerker line systems

The mechanical transmission of power (3): endless rope drives

Power from the tap: water motors

Hand powered drilling tools and machines

Human powered cranes and lifting devices: the sky is the limit

Wind powered factories: the history and future of industrial windmills

The bright future of solar powered factories: we need a renewable source of heat energy

The velomobile: high-tech bike or low-tech car?

Cargo cyclists replace truck drivers on European city streets

Build your own pedal powered machines: overview

Short posts on pedal power can be found at No Tech Magazine


15 of 24 5/13/2014 12:33 PM

Posted on May 25, 2011 at 02:38 PM in Agriculture, Cover story, DIY, Energy production, Factories, Flywheels, Foot

powered machines, Gardening, Human energy, Human powered machines, Kinetic energy, Low-tech solutions, Pedal

power, Treadles, Wireless technology, Zero emissions | Permalink

Comments

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(1)

Some very interesting ideas - I think a modular system that combines a food processor, clothes washing drum and a battery charger would

be an excellent product for many people. You could pedal away while watching television and get work done as well, while saving on

electricity costs and burning calories. There's something waiting for an entrepreneur to make a success of . . .

Posted by: Mehul Kamdar | May 25, 2011 at 07:42 PM

(2)

hi Kris -

Very nice treatise on a niche subject . . i can *humbly* suggest one

more *direct - driven* arrangement at www.juicycle.com - the "

adult-height, arms-reach, multi-kitchen tool prime-mover device" -

developed in California. Although 'wheat grass' juicing is the format,

the typical hand-cranked, kitchen appliance is a low-tech,

"plain bearing" system, and usually iron-on-iron surfaces.

These bearings do not wear especially well when driven from a single

vector, like in the chain-drive illustrated on your page. . . hence

the "steel finger" drive of the type described as 'juicycle' .

. leg-powered, imitating a hand-cranking motion . . low tech

with 'clutching-and-breakaway' safety features are included . . plans available there.

thanks,

wrparker

Posted by: w.r.parker | May 26, 2011 at 02:41 AM


16 of 24 5/13/2014 12:33 PM

(3)

When discussing use of DC power to avoid losses due to added electronics needed, the article states ''there are no DC-laptops'' for

example.

The opposite is true, there are no AC laptops. Invariably, there is a power brick/transformer which converts residential AC (220 or 110)

into DC, between 14 and 18 VDC, depending on the laptop model. So one merely needs to now the output voltage of the power brick to

determine how to feed a laptop.

Posted by: Peter Silva | May 27, 2011 at 11:36 AM

(4)

@3: Thanks. Seems like a switch to a DC-network would make a lot of sense...

Posted by: Kris De Decker | May 27, 2011 at 11:39 AM

(5)

Lloyd Alter at Treehugger notes that the pedal-powered hydraulic log splitter (first illustration) is a silly idea more simply done by hand:

http://www.northerntool.com/shop/tools/product_200316859_200316859

I leave it there since I think the illustration captures the idea of the story very well.

http://www.treehugger.com/files/2011/05/the-forgotten-future-of-pedal-power.php

Posted by: Kris De Decker | May 27, 2011 at 04:31 PM

(6)

Drat! Peter beat me to the punch! I've never seen an AC laptop. For that matter, I've never seen an AC desktop computer. In both cases,

the AC has to be converted to DC to operate the device. It seems like there aren't many devices that work better with AC power. Just about

everything takes the AC and converts it back to DC for operation. I think there are some motors that are designed to run on direct AC -

fans come to mind, maybe compressors. It pretty much has to be something that can run at a constant speed, since the AC current

alternates at a stable 60Hz.

Posted by: KJMClark | May 27, 2011 at 06:34 PM

(7)

With todays cost of photovoltaics it makes more sense to build solar power than pedal power.

Wiring a small house with DC is possible and done sometimes like for camping or on boats. There are 12V tools or adapters for everything

needed in a household.

Today AC is used because it is easy to transform. If the Voltage is doubled there is only half of the current for the same power. Thus wires

can be thinner and transmission losses can be reduced. Long time was not possible to transform one DC voltage to another. So a motor

generator set has to be used. With todays electronically DC/DC converters the grid could be built with DC.

On the other side a pedal powered generator could produce 230V AV directly using an asynchronous generator. the transmission and pole

number of the generator would have to be set so that a convenient and efficient pedal speed can be achieved .

Posted by: matthias | May 29, 2011 at 10:09 PM


17 of 24 5/13/2014 12:33 PM

(8)

I don't think solar and pedal power are incompatible. On the contrary, pedal power could deliver the base load for solar (and wind), being

a solution to the problem of energy storage. If you are prepared to backup your solar system with some pedalling, you will need to install

less solar panels and smaller batteries.

Posted by: Kris De Decker | May 30, 2011 at 01:35 AM

(9)

I and some friends are reading this usefull post we intend to build something, thanks from Brazil :)

Posted by: Juliano Pappalardo | June 05, 2011 at 03:28 AM

(10)

Is a DC generator the best way to link up multiple pedalers or can they be combined to power one machine mechanically without the loss

of electric energy transfer?

Posted by: Seth | June 08, 2011 at 08:52 PM

(11)

I think that there are simpler and more energy efficient tools at least for splitting wood, namely axes, mauls, and wedges.

Posted by: John Trask | June 13, 2011 at 10:23 PM

(12)

Splitting wood using pedal power may not be the best use of the technology BUT you don't need an _adult_ to do the pedaling. The wood

splitting chores could be relegated to children/youth leaving adults free for other tasks.

Posted by: Sandpine | June 14, 2011 at 06:25 PM

(13)

"Human power is available 24 hours per day, is not affected by changes in the weather"

Let's test this. Come down here to South Texas, first in January, and measure how much pedal power you can produce in an hour. Then,

come back in August and re-perform the test. I think you'll find that the weather will have indeed affected your power output (as well as

your health).

Posted by: Tim M | June 19, 2011 at 08:28 AM

(14)

hi-

from a commentator over at http://thearchdruidreport.blogspot.com/2011/06/profligacies-of-scale.html came the referral to an online

pdf for pedal power in work, leisure and transportation at http://www.zetatalk3.com/docs/Pedal_Power

/Pedal_Power_In_Work_Leisure_And_Transportation_1977.pdf the scan is only of medium quality but sufficient for reading. some of

the illustrations and pictures did not scan well.thought this would be of interest to your readers.

clarence


18 of 24 5/13/2014 12:33 PM

Posted by: clarence hale | July 02, 2011 at 10:00 AM

(15)

Clarence: thanks. I should warn readers with slow internet connections that it is a heavy download.

Tim: pedal power is better suited for cooler climates and cooler periods of the year, that is true. But the issue could be solved, for instance

by moving to the basement of an existing house, or by designing buildings that are naturally cooled so that the heat stays out.

Seth: I don't know. I hope a more tech-savvy reader can answer your question.

Posted by: Kris De Decker | July 02, 2011 at 06:03 PM

(16)

I would LOVE to see someone incorporate a Fresnel lens to boil water then attach that motion to the pedals and viola a sun powered

bike...a sun tracker could be used to get continuous power. Alas I have neither the time or resources to persue.

Posted by: Seven | July 05, 2011 at 09:18 PM

(17)

Seth: I'm no mechanic, but I suspect something equivalent to the differential gear in your car (driven backwards, pedal power to the

wheels) would serve to join two slightly-off rotary sources. I'm almost certain you could rig something up; or you might find for your

application a hydraulic transmission system works better; depending on what's doing you can get lower losses than electric that way. (and,

again, depending what you're doing and what resources you have, it can be easier to home-brew)

Kris:

After reading this post, I went looking for "Pedal Power for Work and Transportation" in the local library-- and found a wealth of 70s era

'appropriate tech' resources. Our library is awesome and I thank you for helping me realise that.

Posted by: Tyler August | July 11, 2011 at 04:44 PM

(18)

I found this posting (on a humor website) which I think illustrates your pedal power article nicely.

http://thereifixedit.failblog.org/2011/09/19/white-trash-repairs-laundry-day-is-also-workout-day/

Posted by: Scott | September 21, 2011 at 07:25 PM

(19)

Full plans for a pedal powered juice maker:

http://www.notechmagazine.com/2011/11/when-low-tech-goes-ikea.html

Posted by: Kris De Decker | November 16, 2011 at 05:42 PM

(20)

Very interesting article. I am doing a paper for school and was wondering; everything I have been reading on bicycle generators always

involve a stationary bike. Does anyone know if there is a generator that one could us while using the bicycle in its normal capacity? Thanks

a lot


19 of 24 5/13/2014 12:33 PM

Posted by: Philip DeVerna | November 25, 2011 at 07:05 PM

(21)

Look at the thermodynamics: a human is a heat engine converting biomass (high quality food) to work at maybe 25% efficiency, which is

then used to pedal and drive machinery or batteries.

Conversely, a steam engine can burn biomass (anything) (or take heat from solar, geothermal, or storage), at 20-33% efficiency

(depending on size, bigger's usually better) to then drive machinery or make electricity.

The steam engine/power plant takes more capital, whereas humans come with society. OTOH it's a lot less picky and takes less labor.

1.2 billion pedallers -- yeah, sounds about right. Another approach is to look at power usage (10 kW for the average American, counting all

domestic power use), which at 100 Watts per person is like having 100 mechanical slaves per person.

Posted by: drs | November 30, 2011 at 02:24 AM

(22)

Found another great example of modern pedal power being put to good use: http://blog.makezine.com/archive/2011/12/mobile-

sharpening-rig.html

Posted by: Scott | December 21, 2011 at 10:17 PM

(23)

All computers, internally, operate on 12 v. They can be alternated very easily to by pass AC and operate directly on 12 v. Use a solar panel

to charge the battery if necessary. free info at [email protected]

Posted by: ken hargesheimer | December 25, 2011 at 10:48 PM

(24)

We've built and refined a simple pedal generator that can be built entirely from salvaged materials in about 30minutes, and will provide

plug-in power to any 120VAC appliance that can run on DC as well. By testing we have found that this includes TVs, lights, power tools,

water pumps, vacuum cleaners, blenders. I've got a picture at this link:

http://PublicFiles/PedalGenerator/2009_1010_RollerGenerator.jpg

A 120VDC motor from a discarded treadmill is mounted to a piece of channel that is bolted to a bike training stand, in place of the

resistance unit. All that was necessary was to drill the motor mount to the channel, and the channel to mound to the stand. If you leave the

flywheel on the motor you'll only get about 30V, we used a holesaw to cut the center out of the flywheel and turn it down to make a 2" dia

roller which gives us about 120V when driven by a 27"/700C bike wheel. The motor can be wired directly to an outlet and regular

appliances plugged in. We haven't blown or burned anything up yet, and we've tried quite a few things. The advantage of this approach is

it's quick, and doesn't require any modification of the bike or the appliance that you plug in to. I built this one myself using only a drill

press in 30 minutes. (A friend later made the roller with a holesaw and small lathe.)

Posted by: nick hein | January 28, 2012 at 05:31 PM

(25)

Is it possible to generate electrical power in a sustainable and efficient way on a "mobile" bike (as opposed to a fixed one that I see on the

pictures)? It's probably a very basic question but I'd really appreciate any insights you might want to share. please feel free to email me:

[email protected].

thanks!


20 of 24 5/13/2014 12:33 PM

Posted by: marcos bendrao | February 07, 2012 at 02:28 AM

(26)

Another interesting pedal powered machine using direct mechanical transmission:

http://www.notechmagazine.com/2012/02/pedal-powered-wool-carding-machine.html

Posted by: Kris De Decker | February 09, 2012 at 04:32 PM

(27)

Thank you, thank you, THANK YOU for your "ditch the battery" stance! This cursed box of poison will be the undoing of the "green"

movement. The inefficiency compared to a "mechanical battery" or flywheel is simply unacceptable. The disposal issues are a nightmare!

I have been developing a "human capacitor" along three paths: Flywheel, compressed air, and springs. In each case waste energy (bicycle

braking) is the energy source. Anyone who has ever tried to light a light-bulb with an exercise bike knows that human energy output

compared to consumption is pitiful.... when thought of only in terms of electricity!

Posted by: Johnny Payphone | February 24, 2012 at 07:06 PM

(28)

Just a thought, A big tank on an elevated platform, a little hydraulic ingenuity and all these machines will work (Water motors are well

researched) a pedal powered pump (and a windmill) to fill the tank. Pedal when you want, use the energy when you want. Very low loss

systems. Not a new idea, just a little forgotten.

Posted by: David Mac | April 10, 2012 at 10:38 AM

(29)

Hey People!

Listen, coming from someone who knows a LOT about motors: If you wish to generate electricity with your pedal-powered prime mover,

then DO consider that ugly, HEAVY, bulletproof, 10+HP AC compressor motor that the out-of-business company down the road

abandoned as your generator..

You can Quite easily rectify its output into DC with the use of suitable diodes. This also means that by monitoring a voltmeter whilst you

pedal, you can pretty much CHOOSE the voltage that you want (12 / 24 / 36VDC) without driving the motor to its nameplate speed.

Industrial diodes do have a larger voltage drop, but you can easily find them used and in ample supply.

It is actually common in the electrical / engineering trade to rectify 347/600VAC power supplies with these semiconductors -- and we DO.

Good on us -- stick a PLUG in their dirty oil pipe.

Posted by: CanofSol'n | April 23, 2012 at 02:53 AM

(30)

Question... I am working on a project that includes a bike with a grain milling attachment on it (actually used for grinding coffee). Also, I

would like for the bike to be able to heat water, fairly efficiently if possible. Does anyone have any relevant ideas or links to contribute? It

could use mechanical energy but I am also considering other "sustainable" options. Thanks!

Posted by: Amasa | May 05, 2012 at 03:41 AM


21 of 24 5/13/2014 12:33 PM

(31)

What are your thoughts about a Pedal Powered PTO? A video and website with more information.

http://wellwaterboy.com/id87.html

http://www.youtube.com/watch?v=EMtFlmFqWTs

Seems it can just run anything with a shaft. Something new for this day and era?

Posted by: Lou | November 22, 2012 at 01:52 AM

(32)

Many of the comments about bicycling were false. While aerodynamics are critical to bike speed the seat tube angle is critical to

generating power with your legs. If you sit further back from the crank center you can't 'spin' the pedals very fast which limits the HP and

increases the torque. Conversely most racing bikes have steeper angles which allow less pressure to be applied to pedals spinning much

faster.

If you push very hard at a slow rate your legs will go into 'oxygen debt' and become useless quite soon - 'Spinning' at a rate of 92 beats per

second allows your cardiovascular system to come into play and sustain much, much longer periods of work. Sitting back too far and

pushing too hard will cause harm to your knees as well.

Bicyclists learn to 'spin' in a circular motion which brings more muscles into the game.

Flywheel systems and water transfer energy systems employ sustained small efforts to develop usable large forces - So correctly designing

the 'user interface' would make the difference between a workable system and a novelty (that has potential heath risks).

Many of the designs shown (seats of plastic milk crates?) don't look practical at all from a peddler's perspective.

Many seem to put the peddler at a mechanical disadvantage even as he sits on the thing...

Posted by: Jerry Friedman | December 01, 2012 at 11:28 PM

(33)

While much of the comment is factual, these criticisms of pedal-powered generation are too negative for me. They fail to recognise that

pedal-power generation releases us from the tyranny of centralisation. Activities such as music concerts and cinemas don't have to depend

on the national grid and commercial cinema chains,and they can be done cheaply so the admission price is low.

OK, it IS more efficient to operate machines wihtout electricity if it can be done, but this doesn't mean that bicycle-powered generation

isn't worthwhile.

It would have been educational to show the BEST examples of pedal-powered generation, with a headline like "How to get the most out of

pedal-powered generation"

Please encourage good work, don't trash it.

Posted by: tom foxe | January 03, 2013 at 10:17 PM

(34)

Thank you very much for this article, which has moved my ideas on radically from "I wish I could power my PC with cycling while sitting

at it".

I totally support Mehul Kamdar's comment right at the top. The spin cycle on a washing machine is crying out for a connection to

flywheel-stored energy, eg as generated by Job Ebenezer's dual-purpose bike (which I think answers Marcos Bendrao's comment 25) - I

love the flipped carrier/stand too, btw.

And there's lots of idle time in front of the TV or computer (we'd need new, higher & deeper, desks for the latter, of course) to generate it.

Plus plenty of recent research on how damaging all that sitting around is for our health.

Come on, entrepreneurs, please build it!


22 of 24 5/13/2014 12:33 PM

Posted by: Katherine P | January 13, 2013 at 01:05 PM

(35)

This was really helpful. Having decided to acquire an exercise bike (for fitness) I was really into the idea of using my energy to power

something. Since I don't use mechanical tools (and I don't make smoothies) I would have gone for the rather pointless battery stuff - and

I'd never have been able to generate the embedded energy in the kit. I am hopeless at DIY and not very fit so now I'll just concentrate on

the health benefits (and reducing my energy use). Dee

Posted by: Dee | January 27, 2013 at 07:53 PM

(36)

Articles such as this tend to get my imagination juices flowing. While reading the comments I started thinking along the same lines as the

commentor, David Mac, "A big tank on an elevated platform, a little hydraulic ingenuity and all these machines will work (Water motors

are well researched) a pedal powered pump (and a windmill) to fill the tank. Pedal when you want, use the energy when you want.

My thoughts were even simpler. About a year or so ago there was an article about an invention for afterhours reading or work light for the

developing world which was dirt simple, no battery, just a tiny mechanical generator and an LED bulb. It was powered by gravity. You

simply hung it up, filled a bag with 20 lbs of rock or dirt, lifted the bag a couple of feet and had light for half an hour with each lift of the

bag. They figured the cost for this device in scale quantity would be about $7. This sure seems like a lot simpler solution than the Nepalese

example in this article or storing water up high for an electricity generating water turbine.

It sure seems like a scaled up version of this tech using a bike hooked to a block and tackle lifting a 500 lb to one ton weight up 5 or 6 feet

would be a way to store and supply considerably more power for small electric or mechanical powered in-home industry.

Transfer this to the developed world and a multi-position exersize machine (think Bowflex), not just pedaling, could do the same thing.

For example, exersize for half an hour and you've got enough energy stored to watch 2 hours of TV or whatever. Make use of Michael

Pollen's food and eating principle that you can eat as much junk and deep fried food as you want as long as you make it yourself and have

to deal with the hassle and mess. In this case it's watch as much TV as you want as long as you make the power to do it yourself.

Posted by: Ron Shook | March 03, 2013 at 09:07 PM

(37)

@ Ron:

Great idea. I think you are referring to this "gravity-powered" system:

http://www.notechmagazine.com/2013/01/how-to-design-more-powerful-gravity-powered-lights.html

Posted by: Kris De Decker | March 04, 2013 at 01:49 PM

(38)

haven't we already got potential human power plants? why can't our existing gyms be converted so that, not only pedal power, but all the

other activities like running, leg pulls & pushes, arm and rowing excercises all used to manufacture combined power to be added to the

grid, every town , every city... excercise with a free power bonus! if its too difficiult to convert exising gyms... create new ones with

incentives for super generators... just an idea bg

Posted by: braden godden | March 18, 2013 at 11:16 PM

(39)


23 of 24 5/13/2014 12:33 PM

Found this website looking for kinetic sculpture ideas. I like the idea of gyms as a energy resource and would suggest taking it a little

further having our countries jails setup this way. There seems to be a lot of human power there, that is not being put to good use.

Posted by: Tony | May 11, 2013 at 05:56 PM

(40)

great article, and thanks to the author. reminds me of the Professor on Gilligan's Island! tell Michelle Obama that the fight against obesity

in America's kids can be solved here: if kids want to watch TV, use the internet, or play video games for an hour, they have to pedal a

stationary bike for 30 minutes.

thanks for the inspiration. i hope i can create something out of the suggestions here.

Posted by: jason | February 21, 2014 at 11:17 PM

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