Renewable Energy Zealots Must Understand ‘Net Energy’
Was I surprised that last issue’s column, Can Renewables Outshine Fossil Fuels?, elicited a strong reaction, with written responses of support and derision? Not at all. It’s an issue that continues to divide the environmental community, and one which keeps us from moving forward as quickly as possible to conserve resources and relocalize as an era of cheap, concentrated, easy-to-get energy comes to an end.
My essential argument is that we need to use fast-depleting fossil fuels to create a renewable energy infrastructure even while understanding that renewable energy sources, as some energy researchers are realizing, cannot come close to replacing fossil fuels to meet current energy demand. Moreover, renewables, coupled with massive energy curtailment, will not any time soon become our primary energy source, largely because of various limiting factors, including resource constraints and possible prolonged world economic depression as the debt-based money system unravels.
My critics fail to understand the concept of “net energy,” a full accounting of the energy inputs required to produce a given unit of energy. Renewable energy requires far more imputs of energy, materials and money than do fossil fuels per equivalent unit of energy produced, recent research shows. Especially challenging will be finding a liquid fuel and feedstock alternative to oil, which powers close to 100 percent of global transportation and is ubiquitous in consumer products. No other fuel is as energy-dense, versatile, easily-transportable and abundant as oil. It is the main fuel powering a globalized industrialized civilization and will do so just once.
Here’s my response to some critics’ specific arguments:
Case Western Reserve University physics professor Philip Taylor suggests we “need gather only one part in 2,000” of the sunlight falling upon the earth’s land area to meet our energy needs. While these back-of-the-envelope calculations are presented as veritable proof of solar energy’s availability, a difficult reality emerges. For constructing, installing and maintaining the devices to capture this abundant but diffuse energy is a massive, expensive, fossil-fuel consuming undertaking requiring the mining of finite and ever-scarcer rare-earth minerals and other materials and accruing tremendous human, energy and environmental costs. Yes, we might need to gather only 1 part in 2,000 at current demand. The challenge is doing so in a world with increasing population and declining net energy—with more energy increasingly expended to produce the same amount of useful energy—while fossil fuel production peaks and heads toward collapse, and resource wars intensify.
Taylor also contends that solar cells can be as much as 40 percent efficient, much higher than plants. He misses the forest for the trees when he only looks at end-use efficiency rather than lifecycle efficiency. Is a solar panel really more efficient at capturing sunlight than a tree, considering all of the water and finite fossil fuels used and toxic waste created during its production? A self-replicating tree only requires inputs provided by its immediate environment and is 100 percent recyclable.
Cleveland-area environmentalist Glenn Campbell offered “almost certain technological breakthroughs,” including ones “we can’t foresee today” as evidence that renewables will take care of our energy needs, as if technology itself was the energy source. In fact, technological development has accelerated our energy extraction and use. Even when it’s designed to increase efficiency, it still grows overall energy use (known as Jevons’ paradox). Thus, the more efficient we become, the more we consume. And increasing consumption is our biggest enemy, although it is required for the economic growth needed to try to keep the compounding debt-money system from collapsing.
While rushing to meet current demands with renewables, we should first ask ourselves why we need so much energy in the first place and figure out what can we do better with far less energy. My suggestion is that we reduce our wasteful consumption of energy while we invest our remaining fossil fuels largely in installing decentralized, small-scale renewable technologies that communities can replicate and control. This should be part of a larger integrated initiative to, among other things, relocalize food production, retrofit existing housing stock and establish decentralized systems of zero-interest credit to help businesses, create jobs and stimulate local exchange of goods and services.
These types of measures are critical to addressing our dangerous dependence on those who control the supply and distribution of energy, food, credit and other vital systems—even as we are disempowered through neoliberal globalization to take care of ourselves and our communities. So solar, wind, geothermal and other renewable energy technologies should be viewed as part of a larger vision to create energy-conserving and sustainable local communities. But renewable energy’s limits, compared to fossil fuels, must be understood and its potential contributions not exaggerated.
My problem therefore is not with renewables, but with renewable energy zealots who make pie-in-the-sky calculations that placate policymakers and the public and promote apathy. It’s easier to let some scientists and engineers try to figure out our energy problem for us while we turn up the air conditioning in our 3,000-square-foot homes or drive gas-guzzling SUVs, when it is this very unsustainable lifestyle that is the root of our environmental problems, not fossil fuels.
Renewables won’t save us. We have to save ourselves.
Suggested reading—“Searching for a Miracle: ‘Net Energy’ Limits & the Fate of Industrial Society,” Post Carbon Institute & International Forum on Globalization, September 2009. www.postcarbon.org/report/44377-searching-for-a-miracle
Megan Quinn Bachman is a board member of the Association for the Study of Peak Oil-USA and a Yellow Springs News reporter. She also teaches classes in global ecology and sustainable agriculture at Antioch University Midwest. She can be reached at firstname.lastname@example.org.
By Melissa Gaskill
Two decades ago scientists and volunteers along the Virginia coast started tossing seagrass seeds into barren seaside lagoons. Disease and an intense hurricane had wiped out the plants in the 1930s, and no nearby meadows could serve as a naturally dispersing source of seeds to bring them back.
Restored seagrass beds in Virginia now provide habitat for hundreds of thousands of scallops. Bob Orth, Virginia Institute of Marine Science / CC BY 2.0<p>The paper is part of a growing trend of evidence suggesting seagrass meadows can be easier to restore than other coastal habitats.</p><p>Successful seagrass-restoration methods include <a href="https://www.sciencedirect.com/science/article/abs/pii/S0304377099000078?via%3Dihub" target="_blank">transplanting shoots</a>, <a href="https://onlinelibrary.wiley.com/doi/10.1111/j.1061-2971.2004.00314.x" target="_blank" rel="noopener noreferrer">mechanized planting</a> and, more recently, <a href="https://www.nature.com/articles/s41467-020-17438-4" target="_blank" rel="noopener noreferrer">biodegradable mats</a>. Removing threats, proximity to donor seagrass beds, planting techniques, project size and site selection all play roles in a restoration effort's success.</p><p>Human assistance isn't always necessary, though. In areas where some beds remain, seagrass can even recover on its own when stressors are reduced or removed. For example, seagrass began to recover when Tampa Bay improved its water quality by reducing nitrogen loads from runoff by roughly 90%.</p><p>But more and more, seagrass meadows struggle to hang on.</p><p>The marine flowering plants have declined globally since the 1930s and currently disappear at a rate equivalent to a football field every 30 minutes, according to the <a href="https://www.unep.org/resources/report/out-blue-value-seagrasses-environment-and-people" target="_blank" rel="noopener noreferrer">United Nations Environment Programme</a>. And research published in 2018 found the rate of decline is <a href="https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2018GB005941" target="_blank" rel="noopener noreferrer">accelerating</a> in many regions.</p><p>The causes of decline vary and overlap, depending on the region. They include thermal stress from climate change; human activities such as dredging, anchoring and coastal infrastructure; and intentional removal in tourist areas. In addition, increased runoff from land carries sediment that clouds the water, blocking sunlight the plants need for photosynthesis. Runoff can also carry contaminants and nutrients from fertilizer that disrupt habitats and cause algal blooms.</p><p>All that damage comes with a cost.</p>
The Value of Seagrass<p>As with ecosystems like rainforests and <a href="https://therevelator.org/mangroves-climate-change/" target="_blank">mangroves</a>, loss of seagrass increases carbon dioxide emissions. And that spells trouble not just for certain habitats but for the whole planet.</p><p>Although seagrass covers at most 0.2% of the seabed, it <a href="https://www.unenvironment.org/news-and-stories/story/seagrass-secret-weapon-fight-against-global-heating" target="_blank">accounts for 10%</a> of the ocean's capacity to store carbon and soils, and these meadows store carbon dioxide an estimated 30 times faster than most terrestrial forests. Slow decomposition rates in seagrass sediments contribute to their <a href="https://www.researchgate.net/publication/238506081_Assessing_the_capacity_of_seagrass_meadows_for_carbon_burial_Current_limitations_and_future_strategies" target="_blank" rel="noopener noreferrer">high carbon burial rates</a>. In Australia, according to <a href="https://onlinelibrary.wiley.com/doi/10.1111/gcb.15204" target="_blank" rel="noopener noreferrer">research</a> by scientists at Edith Cowan University, loss of seagrass meadows since the 1950s has increased carbon dioxide emissions by an amount equivalent to 5 million cars a year. The United Nations Environment Programme reports that a 29% decline in seagrass in Chesapeake Bay between 1991 and 2006 resulted in an estimated loss of up to 1.8 million tons of carbon.</p>
Eelgrass in the river delta at Prince William Sound, Alaska. Alaska ShoreZone Program NOAA / NMFS / AKFSC; Courtesy of Mandy Lindeberg / NOAA / NMFS / AKFSC<p>Seagrasses also protect costal habitats. A healthy meadow slows wave energy, reduces erosion and lowers the risk of flooding. In Morro Bay, California, a 90% decline in the seagrass species known as eelgrass caused extensive erosion, according to a <a href="https://www.sciencedirect.com/science/article/abs/pii/S0272771420303528?via%3Dihub" target="_blank" rel="noopener noreferrer">paper</a> from researchers at California Polytechnic State University.</p><p>"Right away, we noticed big patterns in sediment loss or erosion," said lead author Ryan Walter. "Many studies have shown this on individual eelgrass beds, but very few studies looked at it on a systemwide scale."</p><p>In the tropics, seagrass's natural protection can reduce the need for expensive and often-environmentally unfriendly <a href="https://www.nioz.nl/en/news/zeegras-spaart-stranden-en-geld" target="_blank" rel="noopener noreferrer">beach nourishments</a> regularly conducted in tourism areas.</p><p>Seagrass ecosystems improve water quality and clarity, filtering particles out of the water column and preventing resuspension of sediment. This role could be even more important in the future. By producing oxygen through photosynthesis, meadows could help offset decreased oxygen levels caused by warmer water temperatures (oxygen is less soluble in warm than in cold water).</p><p>The meadows also provide vital habitat for a wide variety of marine life, including fish, sea turtles, birds, marine mammals such as manatees, invertebrates and algae. They provide nursery habitat for <a href="https://wedocs.unep.org/bitstream/handle/20.500.11822/32636/seagrass.pdf?sequence=1&isAllowed=y" target="_blank" rel="noopener noreferrer">roughly 20%</a> of the world's largest fisheries — an <a href="https://www.floridamuseum.ufl.edu/science/seagrass-meadows-harbor-wildlife-for-centuries/" target="_blank" rel="noopener noreferrer">estimated 70%</a> of fish habitats in Florida alone.</p><p>Conversely, their disappearance can contribute to die-offs of marine life. The loss of more than 20 square miles of seagrass in Florida's Biscayne Bay may have helped set the stage for a widespread <a href="https://www.wlrn.org/2020-08-14/the-seagrass-died-that-may-have-triggered-a-widespread-fish-kill-in-biscayne-bay" target="_blank">fish kill</a> in summer 2020. Lack of grasses to produce oxygen left the basin more vulnerable when temperatures rose and oxygen levels dropped as a result, says Florida International University professor Piero Gardinali.</p>
Damaged Systems, a Changing Climate<p>Governments and conservationists around the world have already put a lot of effort into coastal restoration efforts. And that's helped some seagrass populations.</p><p>Where stressors remain, though, restoration grows more complicated. <a href="https://www.rug.nl/research/portal/en/publications/the-future-of-seagrass-ecosystem-services-in-a-changing-world(3a8c56db-7bed-4c9e-ac7f-c72453e2a102).html" target="_blank">Research</a> published this September found that only 37% of seagrass restorations have survived. Newly restored meadows remain vulnerable to the original stressors that depleted them, as well as to storms — and <a href="https://www.ecowatch.com/tag/climate-crisis">climate change</a>.</p>
Seagrass in Dry Tortugas National Park, Florida. Alicia Wellman / Florida Fish and Wildlife / CC BY-NC-ND 2.0<p>In Chesapeake Bay a cold-water species of seagrass is currently hitting its heat limit, especially in summer, according to Alexander Challen Hyman of University of Florida's School of Natural Resources and Environment. As waters continue to warm due to climate change, the species likely will disappear there.</p><p>Climate-driven sea-level rise complicates the problem as well. Seagrasses thrive at specific depths — too shallow and they dry out or are eaten, too deep and there isn't enough light for photosynthesis.</p>
But There’s Good News, Too<p>Luckily, left to its own devices, a seagrass meadow can flourish for hundreds of years, according to a <a href="https://royalsocietypublishing.org/doi/10.1098/rspb.2019.1861" target="_blank" rel="noopener noreferrer">paper</a> published last year by Hyman and other researchers from the University of Florida. The researchers arrived at their conclusion by looking at shells of living mollusks and fossil shells to estimate the ages of meadows in Florida's Big Bend region on the Gulf Coast.</p><p>That area has extensive, relatively pristine seagrass meadows. "Our motivation was to understand the past history of these systems, and shells store a lot of history," said co-author Michal Kowalewski.</p><p>A high degree of similarity between living and dead shells indicates a stable area, while a mismatch suggests an area shifted from seagrass to barren sand. The researchers found that long-term accumulations of shells resembled living ones, suggesting that the seagrass habitats have been stable over time.</p><p>That stability allows biodiversity to thrive, creating conditions where specialist species can survive and flourish, according to Hyman.</p><p>Discovering the long-term stability of seagrass meadows has implications for choosing restoration sites, Kowalewski notes.</p><p>"There must be reasons they thrive in one place, while a mile away they don't and fossil data says they probably never did," he said. "If we remove a seagrass patch, we cannot hope to plant it somewhere else. It's not just the seagrass that is special. The location at which it's found is special, too."</p><p>A better approach is conserving these habitats in the first place, but we're not doing enough of that right now. The UN reports that marine protected areas safeguard just 26% of recorded seagrass meadows, compared with 40% of coral reefs and 43% of mangroves.</p>
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