Gaia Stage – Pedal powered low-carbon performance stage, activist research project in response to climate change

GaiaStage 10.06.2024 SRI/SSD2024 Gaia Stage Ry, Sampo Pyhälä, Liisa Tuomi, Dominik Schlienger Pedal powered low-carbon performance stage — activist research project in response to climate change THE GENERATOR is a brushless 24V 116W DC universal motor (generator/ motor) with a 7mm ø axle connected via a sleeve coupling to the 10mm ø axle of the stand’s spindle. The motor’s rpm rating is 4430, the spindle is approx. 30 mm, the bicycle wheel 622 mm. Ideally, the bicycle wheel would need to rotate at 200 rpm. (This is high: averagely we pedal @ 80-100 rpm) GaiaStage Generator Station Existing prototype made of exercise-bicycle stand and 116W 24V DC motor THE STAND we used ships with an adjustable magnetic brake. This brake is replaced by the DC motor via an axle coupling. The stand takes a range of bicycle wheel sizes, from approx. 16-29” wheels. POWER FOR STANDARD 230V EQUIPMENT Audio amplifiers require DC current as a constant reference voltage to generate an (AC) audio signal. To run the Genelec 1029A active speakers, we converted DC first to 230V. Inside the speaker it was converted back to DC. Energy losses can be expected here. A Customised amplifier running on DC only would be more efficient. Nevertheless, we managed to sustain sound pressure levels around 96 dB (1m from speakers) for several minutes. (Hence the set-up in a sound-proof studio) https://youtu.be/8w26jpmnO2g Discernible increases of load on the pedal whenever lower frequency audio was present (when “the bass kicked in”) show the clear need for buffering. THE GAIA STAGE GENERATOR STATION provides energy for the use of lights and audio amplifications on Gaia Stage. As a proof of concept, we connected audio equipment directly to the generator, on the one hand to show what sound pressure levels are possible to achieve by one person pedalling and on the other hand to inform on the need for buffer storage. We ran two experiments: Firstly, we ran a class D amp of a DC boom-box (70W RMS rated) and secondly, a stereo pair of Genelecs 1029A via a 12V 100 Watt inverter (modulated sine wave, 230V) THE DIRECT CURRENT for both experiments passes through an ideal diode, avoiding polarity reversal, and the through a buck-boost regulator, which allows for adjustment of the voltage anywhere between 5-35 V. For the boombox, we set it to 9V, for the inverter, to 13V. POWER FOR 9V BOOMBOX The boombox consists of a 12V car-audio speaker and a class D amp. The sound pressure levels achieved were not measured, but experienced as sufficiently loud for the size of speaker and the location in a residential area. There was no discernible effort needed to keep the system running. The systems rotational inertia was also able to buffer some energy, allowing for pedalling-pauses of a few seconds without the sound interrupting. https://youtu.be/XKMK8CT8NXg The axle coupling and mounting of the generator is rather noisy, probably though suboptimal fitting: The non-standard axle diameter of 7mm needed shimming to fit into the 8mm-10mm adapter. A more professional mounting is needed to reduce noise. THE GENERATOR is a brushless 24V 116W DC universal motor (generator/ motor) with a 7mm ø axle connected via a sleeve coupling to the 10mm ø axle of the stand’s spindle. The motor’s rpm rating is 4430, the spindle is approx. 30 mm, the bicycle wheel 622 mm. Ideally, the bicycle wheel would need to rotate at 200 rpm. (This is high: averagely we pedal @ 80-100 rpm) GaiaStage Generator Station Existing prototype made of exercise-bicycle stand and 116W 24V DC motor THE STAND we used ships with an adjustable magnetic brake. This brake is replaced by the DC motor via an axle coupling. The stand takes a range of bicycle wheel sizes, from approx. 16-29” wheels. POWER FOR STANDARD 230V EQUIPMENT Audio amplifiers require DC current as a constant reference voltage to generate an (AC) audio signal. To run the Genelec 1029A active speakers, we converted DC first to 230V. Inside the speaker it was converted back to DC. Energy losses can be expected here. A Customised amplifier running on DC only would be more efficient. Nevertheless, we managed to sustain sound pressure levels around 96 dB (1m from speakers) for several minutes. (Hence the set-up in a sound-proof studio) https://youtu.be/8w26jpmnO2g Discernible increases of load on the pedal whenever lower frequency audio was present (when “the bass kicked in”) show the clear need for buffering. THE GAIA STAGE GENERATOR STATION provides energy for the use of lights and audio amplifications on Gaia Stage. As a proof of concept, we connected audio equipment directly to the generator, on the one hand to show what sound pressure levels are possible to achieve by one person pedalling and on the other hand to inform on the need for buffer storage. We ran two experiments: Firstly, we ran a class D amp of a DC boom-box (70W RMS rated) and secondly, a stereo pair of Genelecs 1029A via a 12V 100 Watt inverter (modulated sine wave, 230V) THE DIRECT CURRENT for both experiments passes through an ideal diode, avoiding polarity reversal, and the through a buck-boost regulator, which allows for adjustment of the voltage anywhere between 5-35 V. For the boombox, we set it to 9V, for the inverter, to 13V. POWER FOR 9V BOOMBOX The boombox consists of a 12V car-audio speaker and a class D amp. The sound pressure levels achieved were not measured, but experienced as sufficiently loud for the size of speaker and the location in a residential area. There was no discernible effort needed to keep the system running. The systems rotational inertia was also able to buffer some energy, allowing for pedalling-pauses of a few seconds without the sound interrupting. https://youtu.be/XKMK8CT8NXg The axle coupling and mounting of the generator is rather noisy, probably though suboptimal fitting: The non-standard axle diameter of 7mm needed shimming to fit into the 8mm-10mm adapter. A more professional mounting is needed to reduce noise. Stage Designer/Scenographer Sampo Pyhälä •Recycled materials •PET water-bottles" •Bottle crates" •Scaffolding " •Water filled (ballast) GaiaStage Flywheel 2410 mm 2500 mm 2200 mm 800 mm 80 mm 200 mm 300 mm 800 mm BOTTLE CRATES 400 x 300 x 350mm for 12 x 1.5/2l PET bottles held in place by plywood lids fastened by the tension belts 50 mm ø Scaffolding poles (aluminium, 4 mm or mild steel 3.25 mm wall thickness) SCAFFOLDING TUBES wheel: 1m 16 pc. (radial) 0.8m 16 pc. (depth) 0.8m 16 pc. (circumferential) 0.6m 16 pc. (circumferential) Stand: 2.4m 2 pc. 1.9m 2 pc 0.9m 4. pc total lengths: 61.6m Approx. empty weight (incl. pulleys, bearings, connectors and crates/empty bottles) if aluminium (4mm wall thickness): 100 kg; if mild steel (3.25mm wall thickness) 220 kg PULLEYS: A pulley system (2:8 and 3:8) reduces angular speed from 3000rpm to 20rpm, for example. the large pulleys are custom made spokes wheels. STORAGE CAPACITY @ 20 rpm E (flywheel) = 0.5 I⋅ω2 where I is momentum of Inertia and ω is angular speed (in rad/s) Inertia I is k*m*r2 (Where k is a geometric constant (here approx. 0,8); m is the mass of the wheel; and r is its radius.) ω = 20 rpm = (20/60)*2*π rad/sec E (flywheel) = k*m*r2*((20/60)*2π)2 = 0.5*(0.8*759*1.21*(2.0943951)2) = 1,6 kJ This would be sufficient to smooth peaks of approx 750 Watt over a couple of seconds for a performance requiring 250 Watt RMS STORAGE CAPACITY @ 120 rpm E (flywheel) = k*m*r2*((120/60)*2π)2 = 0.5*(0.8*759*1.21*(2.0943951)2) = 58 kJ Via the equivalent Wh (16) this capacity is sufficient to buffer energy for a performance of 5 minutes length at approx. 200 Watt RMS SAFETY: At 120 rpm, the wheel moves 50km/h linear speed i.e., appropriate safety measures are necessary (brakes). 1 MOTOR and 1 GENERATOR mounted on the same axle with ideal diodes to avoid reverse polarity. TENSION BELTS: Wrapped through the horizontal poles, they keep the crates in place. GAIA STAGE FLYWHEEL V1 2410 mm 2500 mm 2200 mm 800 mm 80 mm 200 mm 300 mm 800 mm BOTTLE CRATES 400 x 300 x 350mm for 12 x 1.5/2l PET bottles held in place by plywood lids fastened by the tension belts 50 mm ø Scaffolding poles (aluminium, 4 mm or mild steel 3.25 mm wall thickness) SCAFFOLDING TUBES wheel: 1m 16 pc. (radial) 0.8m 16 pc. (depth) 0.8m 16 pc. (circumferential) 0.6m 16 pc. (circumferential) Stand: 2.4m 2 pc. 1.9m 2 pc 0.9m 4. pc total lengths: 61.6m Approx. empty weight (incl. pulleys, bearings, connectors and crates/empty bottles) if aluminium (4mm wall thickness): 100 kg; if mild steel (3.25mm wall thickness) 220 kg PULLEYS: A pulley system (2:8 and 3:8) reduces angular speed from 3000rpm to 20rpm, for example. the large pulleys are custom made spokes wheels. STORAGE CAPACITY @ 20 rpm E (flywheel) = 0.5 I⋅ω2 where I is momentum of Inertia and ω is angular speed (in rad/s) Inertia I is k*m*r2 (Where k is a geometric constant (here approx. 0,8); m is the mass of the wheel; and r is its radius.) ω = 20 rpm = (20/60)*2*π rad/sec E (flywheel) = k*m*r2*((20/60)*2π)2 = 0.5*(0.8*759*1.21*(2.0943951)2) = 1,6 kJ This would be sufficient to smooth peaks of approx 750 Watt over a couple of seconds for a performance requiring 250 Watt RMS STORAGE CAPACITY @ 120 rpm E (flywheel) = k*m*r2*((120/60)*2π)2 = 0.5*(0.8*759*1.21*(2.0943951)2) = 58 kJ Via the equivalent Wh (16) this capacity is sufficient to buffer energy for a performance of 5 minutes length at approx. 200 Watt RMS SAFETY: At 120 rpm, the wheel moves 50km/h linear speed i.e., appropriate safety measures are necessary (brakes). 1 MOTOR and 1 GENERATOR mounted on the same axle with ideal diodes to avoid reverse polarity. TENSION BELTS: Wrapped through the horizontal poles, they keep the crates in place. GAIA STAGE FLYWHEEL V1 2410 mm 2500 mm 2200 mm 800 mm 80 mm 200 mm 300 mm 800 mm BOTTLE CRATES 400 x 300 x 350mm for 12 x 1.5/2l PET bottles held in place by plywood lids fastened by the tension belts 50 mm ø Scaffolding poles (aluminium, 4 mm or mild steel 3.25 mm wall thickness) SCAFFOLDING TUBES wheel: 1m 16 pc. (radial) 0.8m 16 pc. (depth) 0.8m 16 pc. (circumferential) 0.6m 16 pc. (circumferential) Stand: 2.4m 2 pc. 1.9m 2 pc 0.9m 4. pc total lengths: 61.6m Approx. empty weight (incl. pulleys, bearings, connectors and crates/empty bottles) if aluminium (4mm wall thickness): 100 kg; if mild steel (3.25mm wall thickness) 220 kg PULLEYS: A pulley system (2:8 and 3:8) reduces angular speed from 3000rpm to 20rpm, for example. the large pulleys are custom made spokes wheels. STORAGE CAPACITY @ 20 rpm E (flywheel) = 0.5 I⋅ω2 where I is momentum of Inertia and ω is angular speed (in rad/s) Inertia I is k*m*r2 (Where k is a geometric constant (here approx. 0,8); m is the mass of the wheel; and r is its radius.) ω = 20 rpm = (20/60)*2*π rad/sec E (flywheel) = k*m*r2*((20/60)*2π)2 = 0.5*(0.8*759*1.21*(2.0943951)2) = 1,6 kJ This would be sufficient to smooth peaks of approx 750 Watt over a couple of seconds for a performance requiring 250 Watt RMS STORAGE CAPACITY @ 120 rpm E (flywheel) = k*m*r2*((120/60)*2π)2 = 0.5*(0.8*759*1.21*(2.0943951)2) = 58 kJ Via the equivalent Wh (16) this capacity is sufficient to buffer energy for a performance of 5 minutes length at approx. 200 Watt RMS SAFETY: At 120 rpm, the wheel moves 50km/h linear speed i.e., appropriate safety measures are necessary (brakes). 1 MOTOR and 1 GENERATOR mounted on the same axle with ideal diodes to avoid reverse polarity. TENSION BELTS: Wrapped through the horizontal poles, they keep the crates in place. GAIA STAGE FLYWHEEL V1 Sociologist/Musicologist Liisa Tuomi https://GaiaStage.org