from the world's big
New membrane enables us to harvest 'osmotic' energy from water
You've likely heard of solar energy, but what is osmotic energy?
- Osmotic power plants harvest energy from the difference in pressure or salinity between salt and freshwater using a semi-permeable membrane.
- One of the major challenges for this kind of renewable energy, however, has been developing effective and durable membranes.
- Now, new research demonstrates a durable and effective membrane that could significantly improve osmotic energy collection.
By now, everybody has heard of solar and wind energy. You're probably familiar with hydroelectric energy as well, and maybe even geothermal energy. But few are familiar with osmotic energy.
Osmotic energy plants are fairly rare as one of the key components in their use — a semi-permeable membrane — tends to break down, requiring frequent replacement and driving up operational costs. Now, new research has uncovered a better, more durable membrane that may lead to significantly better returns for this kind of renewable energy.
What exactly is osmotic energy?
An image taken inside of the world's first osmotic power plant at Tofte, Norway, 2009. The project has since been shelved due to its high operating costs, highlighting the need for better, more efficient technology.
POPPE, CORNELIUS/AFP via Getty Images
Osmotic energy takes advantage of the differences in pressure and salinity between fresh and seawater to generate electricity. Its only waste product is brackish water, which is simply water that is saltier than freshwater but less so than seawater. While it doesn't generate large amounts of energy compared to other renewable energy sources, it is remarkably consistent. The energy derived from wind turbines and solar panels fluctuates tremendously with the weather, time, and local climate, but osmotic energy works more or less the same year-round wherever fresh and saltwater meet.
Osmosis, in general, is the process by which liquid moves from a dilute to a concentrated solution through a semi-permeable membrane. It occurs in your body all the time, as its critical for fundamental biological processes.
Osmotic power plants typically use one of two major techniques. In pressure-retarded osmosis (PRO), freshwater is gathered in one tank while saltwater is kept in another. In between, a membrane separates the two. This membrane has special properties that only permit freshwater to pass through, but not saltwater. As a result, the freshwater is drawn through the membrane, diluting the saltwater in the corresponding tank but also raising the pressure. From this pressure, we can derive energy.
The other technique, reverse electrodialysis osmosis (RED), takes advantage of the fact that saltwater contains more positive and negative ions than fresh water. Normally, these ions would travel into the freshwater, balancing out the solution. But when harvesting osmotic energy, a membrane can selectively allow only the positive or negative ions to pass through, turning tanks of salt and fresh water into a kind of battery that passively generates electricity.
Inspired by bone and cartilage
But the reason why we don't see more of either of these plants is because of the membrane. Osmotic membranes are delicate and must retain specific characteristics in order to remain semi-permeable. Exposed to the elements, they tend to degrade over time.
Recent research described in the journal Joule presents a new, durable membrane inspired by bone and cartilage that lasts. This membrane would be used in RED applications.
Bone is a very strong material, but it doesn't permit the transportation of ions, while flimsier material like cartilage permits ions to pass through easily. A membrane for osmotic energy would require both strength and the ability to transport ions.
Using this as inspiration, the researchers developed a membrane consisting of layers of boron nitride and aramid nanofibers. Boron nitride had shown promise in previous membranes but tended to develop cracks over time. To address this, the researchers investigated the use of a class of synthetic fibers frequently used in Kevlar: Aramid nanofibers. By layering boron nitride and the aramid nanofibers, the researchers had developed a material that was sturdy enough to last while remaining flexible and efficient in transporting ions.
The researchers found that not only does this generate power to a similar degree as commercial RED osmotic power plants, but it also performs for a remarkably long time. They cycled the membrane 20 times, observing its efficiency over the course of 200 hours, and found no drop in performance whatsoever.
Moreover, the membrane can function well in a wide range of pH and temperatures. Other membranes only perform well under specific conditions and need to be regularly replaced, increasing the amount of energy they require to be maintained. Implementing a more durable, longer-lasting membrane in a power plant would mean in effect that the plant could generate more power, as it would require less energy to maintain.
While the study only served as a proof of concept, it does show that we're getting better and better at addressing the problems with renewable energy. Not only that, but it highlights how much energy available to us is out there — so long as we're willing to think creatively and look in the right places. With any luck, we might start to see more osmotic energy plants operating at the mouths of the world's rivers.
Higher education faces challenges that are unlike any other industry. What path will ASU, and universities like ASU, take in a post-COVID world?
- Everywhere you turn, the idea that coronavirus has brought on a "new normal" is present and true. But for higher education, COVID-19 exposes a long list of pernicious old problems more than it presents new problems.
- It was widely known, yet ignored, that digital instruction must be embraced. When combined with traditional, in-person teaching, it can enhance student learning outcomes at scale.
- COVID-19 has forced institutions to understand that far too many higher education outcomes are determined by a student's family income, and in the context of COVID-19 this means that lower-income students, first-generation students and students of color will be disproportionately afflicted.
What conditions of the new normal were already appreciated widely?<p>First, we understand that higher education is unique among industries. Some industries are governed by markets. Others are run by governments. Most operate under the influence of both markets and governments. And then there's higher education. Higher education as an "industry" involves public, private, and for-profit universities operating at small, medium, large, and now massive scales. Some higher education industry actors are intense specialists; others are adept generalists. Some are fantastically wealthy; others are tragically poor. Some are embedded in large cities; others are carefully situated near farms and frontiers.</p> <p>These differences demonstrate just some of the complexities that shape higher education. Still, we understand that change in the industry is underway, and we must be active in directing it. Yet because of higher education's unique (and sometimes vexing) operational and structural conditions, many of the lessons from change management and the science of industrial transformation are only applicable in limited or highly modified ways. For evidence of this, one can look at various perspectives, including those that we have offered, on such topics as <a href="https://www.insidehighered.com/digital-learning/blogs/rethinking-higher-education/lessons-disruption" target="_blank">disruption</a>, <a href="https://www.nytimes.com/2020/02/20/education/learning/education-technology.html" target="_blank">technology management</a>, and so-called "<a href="https://www.insidehighered.com/sites/default/server_files/media/Excerpt_IHESpecialReport_Growing-Role-of-Mergers-in-Higher-Ed.pdf" target="_blank">mergers and acquisitions</a>" in higher education. In each of these spaces, the "market forces" and "market rules" for higher education are different than they are in business, or even in government. This has always been the case and it is made more obvious by COVID-19.</p> <p>Second, with so much excitement about innovation in higher education, we sometimes lose sight of the fact that students are—and should remain—the core cause for innovation. Higher education's capacity to absorb new ideas is strong. But the ideas that endure are those designed to benefit students, and therefore society. This is important to remember because not all innovations are designed with students in mind. The recent history of innovation in higher education includes several cautionary tales of what can happen when institutional interests—or worse, <a href="https://www.insidehighered.com/news/2016/02/09/apollos-new-owners-seek-fresh-start-beleaguered-company" target="_blank">shareholder</a> interests—are placed above student well-being.</p>
Photo: Getty Images<p>Third, it is abundantly apparent that universities must leverage technology to increase educational quality and access. The rapid shift to delivering an education that complies with social distancing guidelines speaks volumes about the adaptability of higher education institutions, but this transition has also posed unique difficulties for colleges and universities that had been slow to adopt digital education. The last decade has shown that online education, implemented effectively, can meet or even surpass the quality of in-person <a href="https://link-springer-com.ezproxy1.lib.asu.edu/article/10.1007/s10639-019-10027-z" target="_blank">instruction</a>.</p><p>Digital instruction, broadly defined, leverages online capabilities and integrates adaptive learning methodologies, predictive analytics, and innovations in instructional design to enable increased student engagement, personalized learning experiences, and improved learning outcomes. The ability of these technologies to transcend geographic barriers and to shrink the marginal cost of educating additional students makes them essential for delivering education at scale.</p><p>As a bonus, and it is no small thing given that they are the core cause for innovation, students embrace and enjoy digital instruction. It is their preference to learn in a format that leverages technology. This should not be a surprise; it is now how we live in all facets of life.</p><p>Still, we have only barely begun to conceive of the impact digital education will have. For example, emerging virtual and augmented reality technologies that facilitate interactive, hands-on learning will transform the way that learners acquire and apply new knowledge. Technology-enabled learning cannot replace the traditional college experience or ensure the survival of any specific college, but it can enhance student learning outcomes at scale. This has always been the case, and it is made more obvious by COVID-19.</p>
What conditions of the new normal were emerging suspicions?<p>Our collective thinking about the role of institutional or university-to-university collaboration and networking has benefitted from a new clarity in light of COVID-19. We now recognize more than ever that colleges and universities must work together to ensure that the American higher education system is resilient and sufficiently robust to meet the needs of students and their families.</p> <p>In recent weeks, various commentators have suggested that higher education will face a wave of institutional <a href="https://www.businessinsider.com/scott-galloway-predicts-colleges-will-close-due-to-pandemic-2020-5" target="_blank">closures</a> and consolidations and that large institutions with significant online instruction capacity will become dominant.</p> <p>While ASU is the largest public university in the United States by enrollment and among the most well-equipped in online education, we strongly oppose "let them fail" mindsets. The strength of American higher education relies on its institutional diversity, and on the ability of colleges and universities to meet the needs of their local communities and educate local students. The needs of learners are highly individualized, demanding a wide range of options to accommodate the aspirations and learning styles of every kind of student. Education will become less relevant and meaningful to students, and less responsive to local needs, if institutions of higher learning are allowed to fail. </p> <p>Preventing this outcome demands that colleges and universities work together to establish greater capacity for remote, distributed education. This will help institutions with fewer resources adapt to our new normal and continue to fulfill their mission of serving students, their families, and their communities. Many had suspected that collaboration and networking were preferable over letting vulnerable colleges fail. COVID-19's new normal seems to be confirming this.</p>
President Barack Obama delivers the commencement address during the Arizona State University graduation ceremony at Sun Devil Stadium May 13, 2009 in Tempe, Arizona. Over 65,000 people attended the graduation.
Photo by Joshua Lott/Getty Images<p>A second condition of the new normal that many had suspected to be true in recent years is the limited role that any one university or type of university can play as an exemplar to universities more broadly. For decades, the evolution of higher education has been shaped by the widespread imitation of a small number of elite universities. Most public research universities could benefit from replicating Berkeley or Michigan. Most small private colleges did well by replicating Williams or Swarthmore. And all universities paid close attention to Harvard, Princeton, MIT, Stanford, and Yale. It is not an exaggeration to say that the logic of replication has guided the evolution of higher education for centuries, both in the US and abroad.</p><p>Only recently have we been able to move beyond replication to new strategies of change, and COVID-19 has confirmed the legitimacy of doing so. For example, cases such as <a href="https://www.washingtonpost.com/education/2020/03/10/harvard-moves-classes-online-advises-students-stay-home-after-spring-break-response-covid-19/" target="_blank">Harvard's</a> eviction of students over the course of less than one week or <a href="https://www.nhregister.com/news/coronavirus/article/Mayor-New-Haven-asks-for-coronavirus-help-Yale-15162606.php" target="_blank">Yale's apparent reluctance</a> to work with the city of New Haven, highlight that even higher education's legacy gold standards have limits and weaknesses. We are hopeful that the new normal will include a more active and earnest recognition that we need many types of universities. We think the new normal invites us to rethink the very nature of "gold standards" for higher education.</p>
A graduate student protests MIT's rejection of some evacuation exemption requests.
Photo: Maddie Meyer/Getty Images<p>Finally, and perhaps most importantly, we had started to suspect and now understand that America's colleges and universities are among the many institutions of democracy and civil society that are, by their very design, incapable of being sufficiently responsive to the full spectrum of modern challenges and opportunities they face. Far too many higher education outcomes are determined by a student's family income, and in the context of COVID-19 this means that lower-income students, first-generation students and students of color will be disproportionately afflicted. And without new designs, we can expect postsecondary success for these same students to be as elusive in the new normal, as it was in the <a href="http://pellinstitute.org/indicators/reports_2019.shtml" target="_blank">old normal</a>. This is not just because some universities fail to sufficiently recognize and engage the promise of diversity, this is because few universities have been designed from the outset to effectively serve the unique needs of lower-income students, first-generation students and students of color.</p>
Where can the new normal take us?<p>As colleges and universities face the difficult realities of adapting to COVID-19, they also face an opportunity to rethink their operations and designs in order to respond to social needs with greater agility, adopt technology that enables education to be delivered at scale, and collaborate with each other in order to maintain the dynamism and resilience of the American higher education system.</p> <p>COVID-19 raises questions about the relevance, the quality, and the accessibility of higher education—and these are the same challenges higher education has been grappling with for years. </p> <p>ASU has been able to rapidly adapt to the present circumstances because we have spent nearly two decades not just anticipating but <em>driving</em> innovation in higher education. We have adopted a <a href="https://www.asu.edu/about/charter-mission-and-values" target="_blank">charter</a> that formalizes our definition of success in terms of "who we include and how they succeed" rather than "<a href="https://www.washingtonpost.com/opinions/2019/10/17/forget-varsity-blues-madness-lets-talk-about-students-who-cant-afford-college/" target="_blank">who we exclude</a>." We adopted an entrepreneurial <a href="https://president.asu.edu/read/higher-logic" target="_blank">operating model</a> that moves at the speed of technological and social change. We have launched initiatives such as <a href="https://www.instride.com/how-it-works/" target="_blank">InStride</a>, a platform for delivering continuing education to learners already in the workforce. We developed our own robust technological capabilities in ASU <a href="https://edplus.asu.edu/" target="_blank">EdPlus</a>, a hub for research and development in digital learning that, even before the current crisis, allowed us to serve more than 45,000 fully online students. We have also created partnerships with other forward-thinking institutions in order to mutually strengthen our capabilities for educational accessibility and quality; this includes our role in co-founding the <a href="https://theuia.org/" target="_blank">University Innovation Alliance</a>, a consortium of 11 public research universities that share data and resources to serve students at scale. </p> <p>For ASU, and universities like ASU, the "new normal" of a post-COVID world looks surprisingly like the world we already knew was necessary. Our record breaking summer 2020 <a href="https://asunow.asu.edu/20200519-sun-devil-life-summer-enrollment-sets-asu-record" target="_blank">enrollment</a> speaks to this. What COVID demonstrates is that we were already headed in the right direction and necessitates that we continue forward with new intensity and, we hope, with more partners. In fact, rather than "new normal" we might just say, it's "go time." </p>
Russian astrophysicists propose the Casimir Effect causes the universe's expansion to accelerate.
- Astrophysicists from Russia propose a theory that says dark energy doesn't exist.
- Instead, the scientists think the Casimir Effect creates repulsion.
- This effect causes the expansion of the universe to accelerate.
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