Cleantech
The Biosphere’s Guide to Fool-Proofing Sustainability, Part 4:
Power Autonomy

Nature has discovered that if you want to sustain your value cycles for billions of years, they need to run on free flows of solar energy. Our products and processes need to do the same.

This is the fourth in a seven-part series on what author Gregory Unruh calls the ‘Biosphere Rules.’ Read parts one, two and three.

Power Autonomy

Biosphere Rule #3: Maximize the power autonomy of products and processes, so they can function on renewable energy.

Biosphere Rule #3 — Power Autonomy — is about optimizing the energy independence of products and systems so that they can run on available free flows of renewable energy. Power autonomy is gained by maximizing the efficiency of energy generation and use in products and production processes. By doing so, you minimize energy demand — allowing products to operate longer on any given amount of energy, extending the autonomy of the system. Lower power demand also reduces the size of both renewable energy generation and storage needs, opening the possibility that energy capture, generation and storage can be integrated into the products and systems themselves.

Of course, the biosphere has already figured this out. A cactus, for example, has energy generation, storage and use built into it. The succulent’s green skin provides both protection from the elements and incorporates chlorophyll, which allows the cactus to capture solar energy. The energy is used to produce biomass (made from the parsimonious CHON materials pallet), which serves for both the plant’s growth and energy storage. The cactus can operate, replicate and survive with significant power autonomy, thanks to this clever design.

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Circular economists implementing Biosphere Rule #3 need to understand the relationship between the three key Power Autonomy variables: generation, efficiency and storage. As shown in Figure 1, the amount of storage needed is a function of a system’s energy efficiency and its ability to generate energy. As efficiency increases, less energy-generation capacity is needed. An LED light bulb needs about one-tenth of the power that an incandescent bulb needs to produce the same amount of light, so it needs much less generation capacity. The same is true for storage. The more efficient the system, the fewer batteries you need to keep it operating.

Figure 2 illustrates the process of guiding your products and facilities towards Power Autonomy over time. Assume that your company today is operating on 80 percent fossil fuels. You can begin by investing in the energy efficiency of your manufacturing processes to drive down total power demand. You’ll need less energy to produce the same result, as illustrated in the downward sloping line. Now, at the same time, if you begin transitioning over to renewable energy generation, you drive up the amount of renewable power you use, as illustrated by the upward sloping line. Eventually the lines meet at a crossover. This is the Power Autonomy Convergence Point, where the amount of energy you need equals the amount of renewable energy you're generating. You've now created a power-autonomous production process or product. You can measure that progress by the Power Autonomy Factor, which measures the percentage of renewable energy over the total energy demand. The idea is to drive down your total energy demand and balance it out with increasing renewable energy generation.

Again, storage is also important in this transition because, for environmental sustainability reasons, we need to move away from fossil-based fuel-generation systems. If you have “instant on” fossil fuel generation, and you can turn it up and down as you need with complete variability, you don't need any storage. But because the sun doesn't always shine and the wind doesn't always blow, renewable energy generation is not constant. One strategy to deal with this is to diversify your energy sources so that when the wind slacks, tidal or solar supplies can supplement. But at some point, for power autonomy reasons, you will need storage in the system. Again, these three variables are interlinked and the key thing to remember is that if you're wasteful, you need more generation and storage; if you're energy-efficient, you need much smaller storage and generation systems.

A number of products already have integrated generation and storage. A hybrid car’s regenerative braking, for example, captures the energy that you normally lose to the friction of hot breaks. If you've ever looked at the dashboard of a Prius, you'll see arrows that show how the energy is flowing between the battery and the motor. Normally, the power goes from the battery to motor to drive the wheels; but when you step on the brakes, the Prius actually reverses the energy flow, running it back to the battery, rather than wasting it as heat. And it’s not just cars — Otis Elevators have a regen unit built into them that allows the recapture of energy. Normally, elevators use energy to take people up and then use more energy to slowly lower them down. The idea with the Otis Elevator is that when you load people up on the top floor and take them down to the ground floor, the potential energy can be captured and used to regenerate batteries in the system.

Nature has discovered that if you want to sustain your value cycles for billions of years, they need to run on free flows of solar energy. We need to do the same.

Dr. Gregory C. Unruh is the Sustainability Editor for the MIT Sloan Management Review and author of the new book, The Biosphere Rules: Nature’s Five Circularity Secrets for Sustainable Profits*. For a limited time, Sustainable Brands subscribers can download a complimentary digital copy of the book* here.

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