Update on OSU human power installation

April 1st, 2009 | Brandon

With apologies for the gap between blog entries, I thought it might be time to write a little (or a lot) more about the installation of “human power” harvesting at our Dixon Recreation Center.

The press coverage OSU received as a result of this innovative installation exceeded even my expectations, and responses have been overwhelmingly positive.  Many have called or written me for more information and details about the vendor, the equipment and how it’s all working out.  I have not had time to respond individually to each inquiry, so my hope is that this longer response might serve to answer all the common – and some of the uncommon – questions.  Also, please post questions to this blog rather than emailing me and I will respond here; I’ve received many similar questions, so it would be great to share the responses with everyone.

The basics. The system is comprised of just a few key components: 22 elliptical exercise machines, 2 inverters, AC and DC wiring, and a display computer. The ReRev technology is in the inverters, which act much like solar inverters in that they take DC power generated by the elliptical machines and convert it to AC power that is fed back onto the utility grid. This building, like most, consumes far more electricity even “idling” than these 22 units will ever produce, so all the power generated is consumed on site in that facility.  We do have expansion capability, however, of up to 40 machines with the existing inverters, and we wired to add at least one more inverter eventually.

Each elliptical machine can generate up to 400 watts with a beefy user at a full sprint.  Even the best athletes couldn’t maintain that output for long.  Most users operate the machines at lower-than-we-expected resistance levels, which is contributing to a bit less output than we expected (more details on this below).

Getting it done. Installation went very smoothly thanks to our great Rec Sports staff and their contracted electricians Cherry City Electric, the vendor ReRev and Pacific Power, the local electrical provider.  Pacific Power was great in working with this clearly out of the box request.  The actual install only took a few days, with some tidying up over a few more days.

Part of the beauty of this system is the simplicity.  Because the elliptical machines come from the factory with DC generation capacity (that’s what provides the programmable, variable resistance for your workout) no modifications to the exercise equipment were necessary.  In the factory setup, DC current that provides resistance is burned off – literally – in small ceramic heaters inside each machine.  Not so wise to create heat in exercise facilities that need a lot of annual cooling, eh?  Rather than running heat-making resisters, DC wiring is run from the ellipticals to ReRev’s special inverters, and AC wiring connects the inverters to a building electrical panel.  We ended up with a nice, clean installation with a little help from under floor conduit.

Funding and cost. Funding for the project came from three sources: a grant from the Energy Trust of Oregon, from the OSU Student/Incidental Fees Committee – a student body governing student fee rates and how that money is spent, and from the Recreational Sports department.  Total project cost was in the $17-19k range.

A few people have asked if they could set this up in their homes.   Technically, yes, but it would be very expensive for one or two exercise machines.  Maybe we should suggest that ReRev create a mini inverter? Maybe they’re working on one already…?

Performance and expectations. As mentioned, installation went smoothly and we have a clean install but output is not quite there yet.  When you’re one of a kind, you have to learn as you go, and that’s what we plan to do.  We are a research university, after all!

Regarding output, we are seeing per machine production in the 15-40 watt range, with some peaks much higher.  But sadly, short duration peaks are not where you make much energy (this is the difference between kilowatts and kilowatt-hours).  We would like to see sustained outputs in the 50 watt range to be closer to our expectations.  I should point out, however, that this is the largest installation of it’s kind in the world – at this level of innovation, our original targets were guesses in the dark.  Nowhere else are these machines interacting with so many others.  We are working with the vendor and will continue until we have tried tweaking every possible aspect to get maximum electrical output.  I will update this blog and the sustainability website as we learn more.

Payback and benefits. I’ve received a lot of questions about the “payback” for this project.  Strictly financially, it’s not great.  Even accounting for building air conditioning (cooling) savings plus the expected electrical output, financial break-even is over 20 years.  But it’s is similar to many energy technologies during early stages of development.  This technology is not unlike photovoltaic, which faces large financial hurtles but is still recognized as one of the biggest players as a renewable energy solution for the future.  A university environment where innovation is fostered makes for the perfect living laboratory for wacky things like inverters hooked to exercise machines.  And for the technology to be perfected.

Remember, conservation is almost always the cheapest way to reduce energy costs and environmental impact.  And even though this is not a conservation project, I think it will have a significant conservation impact.  In what other way can you equate your sweat volumes to one of the dozens of everyday uses of electrical power?  How long do you have to pedal to run your iPod all day, or to watch TV for an hour?  (Flat panel or CRT TV?)  How much extra time to have to stay on the machine to “pay for” those extra five minutes of hot water in the shower this morning?

As my friend Jan Schaeffer from the Energy Trust said, “This gives you a whole new relationship with a kilowatt hour.”

My hope is that this new relationship fosters awareness in the non-choir – the masses who haven’t thought about their energy consumption much until now.  If in that way OSU’s productive ellipticals reach even a few people, the return will outlast and out-reach this fun little project.


5 Responses to “Update on OSU human power installation”

  1. Brandon says:

    Jessica,
    It’s a good question. I’m not sure OSU still has the largest installation of this kind, but I think there are certain economies of scale that need to be considered when investigating this type of equipment. In our case, we have two inverters that can each take about 15 machines’ worth of output. We needed two inverters because we hooked up 22 machines, but the cheapest price points are with 15 and 30 machines hooked up.

    I would check with the vendor about the best price points because I bet they have changed since 2009. Vendors and installers are used to getting these types of questions and should have performance data from other installations ready to share with you.

    Good luck,
    Brandon

  2. Jessica says:

    I have a question about the break even concerning pay off – I understand that OSU has the largest installation of these machines – is that why it will take so long for the pay off to break even? would there be a way we could see statistics on the amount of machine use comparative to the watt out put? Just assessing to see if this is an investment worth pursuing for my university.

  3. This is such a good idea to have people exercising on elliptical machines helping to power the building. Would you be able to start some kind of program where a big group of people go to work out on the elliptical machines at the same time to generate more electricity?

  4. Great article and great topic. Its good to hear that the installation went very smoothly. Hopefully the project will come in under budget for you. keep up the great work.

  5. [...] Sponsored by the Student Sustainability Initiative and OSU Recreational Sports, the Energy Civil War is an annual event “charging” OSU and UO to see who can generate the most power with our grid-tied exercise equipment. [...]