Current Events: Leaky Leaky

2016 has been a big year for oil pipeline leaks. After a long and ridiculous battle between the standing rock protesters and the Energy Transfer Partners (ETP), finally, the Dakota access pipeline is going to be re-routed. For those of you who still think that these protesters are "anti-energy," I would urge you to look 200 miles away, where a crude oil pipeline leaked into Ash Coulee Creek this past week.

Picture from the Ash Coulee Creek leak 

The significance of this leak is that it happened so soon after the decision to re-route the Dakota Access Pipeline; the actual occurrence of this leak is in no way surprising. This isn't the first time this Bell Fourche Pipeline has failed; according to the US Department of Transportation, the Bell Fourche company has "had 10 reported spills over the past five years. Those spills accounted for the loss of nearly 5,000 barrels of oil and caused $2.26 million in property damage." Clearly, to this company the cost of leaking twice a year is not enough for them to invest in better pipes. Here are more oil pipeline statistics in the U.S. For your convenience, here is a chart that summarizes all the stats:

Over the last 20 years, oil leaks have cost almost $7 Billion dollars in the U.S. Not to mention, there are fatalities associated with these incidents, which no amount of money can quantify. These pipelines leak all the time! No wonder the Standing Rock protesters stood in the cold for countless hours. 

So why do these pipelines leak all the time? There are multiple reasons, the most important being lack of inspections. As we learned in class, higher viscosity fluids require greater pressure to move, which is why costs are already high for these companies that transport crude oil. Thus, they compensate by not putting in the money required for inspections of these often aging pipelines. If these companies considered oil leaks truly unacceptable, they would invest in more secure pipes that can last the wear and tear of the whether. Further, going back to the high cost of moving the crude oil, the companies don't even want to shut down the pipeline if they do hypothetically find an issue. The opportunity cost of stopping and starting is probably so high (once again due to the viscous nature of crude oil) that they'd rather wait to stop only if they desperately need to. 

This oil spill right near Standing rock taught all pipeline enthusiasts a lesson--pipe standards for oil transportation is not where they need to be. So even if Standing Rock is safe, the Dakota Access Pipeline should be considered an accident waiting to happen wherever it is built. The same can be said about the Keystone Pipeline. We cannot let the lucrative nature of the oil business blind us from the fact that oil pipeline standards are poor, and that there needs to be some intervention (unlikely to happen in the next 4 years). Additionally, if a country like the U.S. doesn't have appropriate investment in these pipelines, you can imagine the state of countries like Venezuela, which have inferior technology and an economic dependence on oil. Unless something is changed, get ready for more oil spills.

Life Isn't Steady

Transport Student A: "So what do we do?" 

Transport Student B: "Well, at least we can assume steady-state, so let's cut that term out of the Navier-Stokes equation."

Does the above dialogue sound familiar? Those two lines are basically how most fluid mechanics or transport students begin their problem sets. Well, students from Princeton University and University of Virginia show in the video below that natural phenomena, like bugs flying and dolphins swimming really fast, cannot be explained by cutting the unsteady term out of the equation. If the unsteady term is not taken into account, the average bee would fall and the average dolphin would not be able to swim at 34 miles per hour. 

What this video is really about is explaining how animals have been able to achieve very efficient motion through fluids due to their body shape and unsteady movement of fins/wings. This unsteady movement apparently reduces the drag (viscous drag) for the animals. The perfect example of this is the Manta Ray. Apparently Manta Rays are 95% efficient in propulsion. Further, our modern day propellers, which are basically fans in water, are in fact very inefficient. Basically the video tells us that manta rays are really cool, though I am not so sure I can say the same about the corny Coldplay music they had playing in the background. Nonetheless, the researchers from the two universities wanted to imitate manta rays and possible develop a more efficient propulsion system.

What they did was pretty interesting--they scanned a manta ray fin, modeled it in CAD, made its negative, and 3-D printed it. They then used this mold and a fish pasty material to create their own artificial manta-ray fin. Additionally, they attached four rods to the mold as well, simulating the muscles. The four rods were attached to four gears and made to rotate out of phase from one another, simulating wavelike motion for the fin. The fin then actually swam at speeds in the order of magnitude of a manta ray!

To me, this shows that biological and evolutionary advancements often beat human technological advancements. Dolphins and manta rays have developed their fins over thousands of years of evolution--so do we really think that a fan in water is gonna be better than that? Imitating the rest of nature has therefore always been what scientists strive for. Finding more of these archetypes in nature can really help us advance as a society. Who knows what else we can do? Another great example of this biomimicry is water resistant clothes using the same nanoscale bumps in lotus leaves (I talk about them in one of my previous blogs!). More examples can be found in this link here.

Light Bulbs from Mixing

Assistant professor Ngai Yin Yip (EEE department) delivered an excellent talk for the Chemical engineering department on his PhD thesis and current research, which delves in the intersectionality between renewable energy and climate change. I was quite amazed because his research harnessed energy from the most unlikely source—mixing. Who would ever think that you can get energy from mixing salt in water? What I also found cool was that the energy from salt gradients does not come mostly from enthalpy of mixing, but the entropy of mixing. Salt prefers to dissolve because it can be more places when dissolved as opposed to in a crystal. I find that a really fundamental idea that makes so much sense. In a way, this research is the opposite of desalination—rather than putting in energy and separating salt from water, it is using the natural release of energy of mixing. I have since told multiple people (friends and family) about the idea that mixing is a renewable energy source and they were all immediately confused. It seems that it is a very non-intuitive idea for most of those who do not have a science background.

But what is the mechanism for gathering this energy? It’s none other than pressure driven flow! Basically, there is less salty water and very salty water separated by a semi-permeable membrane that only allows water to traverse. The water from the less salty water then crosses to the other side and the energy of this pressure driven flow is harnessed through a piston. The talk primarily focused on details about how to improve this process, and included some interesting techniques including running the process upside down in order to clean the membrane of gunk (called fouling). But what I found interesting, and a little suspicious about the whole thing, was that Professor Yip only spoke about the mechanical energy harnessed. Yet he compared the mechanical energy harnessed from this source to electrical energy from solar power and other renewable energy sources. Albeit, doing my own research, the efficiency in converting water turbine energy into electrical energy is as high as 90%, this still marks an important further loss that he didn’t take into account.

Lastly, how can this source of energy be used practically? Professor Yip gave one way, which is when fresh water and sea water meet, and there is a water potential between them. However, I found that scientists have proposed another use—which is how this research applies to climate change as well. Desalination results in salty water, and chemically treated wastewater has very little salt content. So scientists have proposed combining the two, and harnessing energy from that! Thus this process has real applications and can be a great energy source for the future. 

Bonus Blog: Surface Tension and Lotus Leaves

Do you ever wonder what happens when a Lotus leaf gets wet? What if it rains, and the leave gets soaked? Why doesn't the leaf get wet and, due to the added weight of the water, sink into the pond? The answer to these questions are much more complicated than one would think, and it has a lot to do with surface tension.

A Picture of Lotus Leaves

In class we learned that surface tension is the tendency of water to minimize its surface area. So if given a chance, water will bead up into as much of a sphere as it can. The lotus uses the surface tension of water to its advantage. Lotus leaves are ultrahydrophobic--they can't get wet. So when you put water on the top of a lotus leaf, it will bead up and roll out of the leaf! So rain water simply rolls away. How does this happen? Well first let's go through the most common guess people have when I have asked them this question--wax. One could think that maybe some sort of wax on the leaf is causing the water to bead up. Wax is non-polar, so water does not want to mix with wax and therefore rolls of the leaf. This only partially true, since Lotus leaves do have a coating of epicuticular waxes, however this does not explain the entire story. Waxes are temporary and keep regenerating, but they are not a full proof way to keep the leaves from getting wet. Again, Lotuses are ULTRA-hydrophobic.

The answer actually lies in the very geometry of Lotus leaves. They may look like plain old leaves from afar, but if you look a little closer (okay a lot closer), something really interesting is observed. Scanning electron microscope images of Lotus leaves show the following structure:

These structures are little bumps and hills, and they are only seen on the side of the lotus leaf facing the sky. The surface of a lotus leaf is in fact very rough; you just can't see or feel the roughness. These bumps reduce the contact area between water and the leaf. The less water is in contact with the leaf, the more it will want to turn into a sphere due to its high surface tension. The graphic below gives a good idea of what I mean:

This rough structure, along with the wax coating, makes it impossible for the lotus leaf to get wet. But there's more. The lotus leaf is always really clean--a reason why in Asia it is associated with cleanliness, beauty, and also sometimes holiness. This is because the water droplets that fall on the leaf are cleaners! The picture below shows how a water droplet can pick up dirt and clean the leaf as it rolls away.

So not only do Lotus leafs not let water touch them, they also make the water clean them as well, allowing for more exposure to the sun. Now, its obvious where this is going--do we have technology like this for humans? The answer is yes--you can actually get clothes and materials that mimic the lotus leaf. So you can actually buy clothing that is ultrahydrophobic, so no matter how awful you are at drinking, your clothes will be stain free. Look at this cool video as an illustration:

So if you have kids who always spill things on themselves, the answer lies in the lotus leaf!

Lock Out Tag Out

The more technology progresses, the greater the chances we're gonna get hurt. Process safety is an important theme in any workplace, which is why I have decided to blog about a very important concept within process safety, called Lock Out Tag Out.

When working in any plant, automated machinery often works on hazardous sources of energy--electricity, hydraulic energy, high pressure pneumatic energy etc. Since hydraulic and pneumatic energy are high pressure fluids, this concept of lock out tag out is very relevant to this blog. As an introduction, I will ask an important question: When multiple people are working on the same machinery, how do you create a system where one person's mistake does not hurt someone else, and compound the issue even further?

To further illustrate the problem the above question brings to attention, lets suppose 10 workers are working in a plant that manufactures diapers. The diaper has many parts to it, and making parts of it require, other than electricity, strong vacuums and air power as well. The machine needs to be cleaned and shuts down. 9 of the 10 workers finish cleaning their parts of the machine. It's been a long day they just want to start the machine again, because their bosses will be mad if they don't. The 9 workers look at each other, think everyone is done and start the machine back up, forgetting to count the 10th worker. The 10th worker is still inside the large diaper making machine, while it turned on. The pneumatic energy and electrical energy are now both active and the 10th worker's life is in serious threat.

To prevent a situation like this, there needs to be a system where if any worker is working on the machine, its electrical and pneumatic energy cannot be activated. This system is lock out tag out. In factories like the one above, when any worker shuts the machine down, they must lock the on/off switch so nobody but them can open it. Each worker has his/her own set of locks. Thus, in the situation above, the 9 workers would not be able to turn the machine on because the 10th worker's lock would still be on the on/off switch. Many workplace incidents are caused due to failure to lock out, and is a serious safety violation for most companies. Workers often think its okay to just quickly finish a job without locking out, which is why companies must give the biggest disincentive for such behavior.

Example of proper locking

Random Explained

I still don't really get turbulence. I know it can be quantified with average velocities, but why does it happen? While we may not have all the answers, the below video narrated by Robert W. Stewart, of the University of British Columbia, does a great job of explaining this perceived randomness. Stewart smokes his pipe, and lets us know that Turbulent flow is not necessarily random as we think.

Like in my transport class, he goes over the Reynolds number and why turbulent flow is about high Reynolds numbers (much greater than 2000). He also defines turbulent flow has having disorder, vorticity, and efficient mixing. For a video that seems to have been made half a century ago, the illustrations and experimentation were very clear. As viscosity was decreased, the flow turned turbulent and the pressure gradient increased. He also explains that this increase in pressure is due to the Reynolds stress, or the additional stress in turbulent flow compared to laminar flow.

But the part that I found cool was that if a funnel was put in at the entrance, the flow was laminar for a greater Reynolds number (around 8000). The video says that the funnel makes the flow smoother and less mixing happens, making more laminar flow. Thus, once again, turbulent flow is not random, and the number 2000 is not random either; it applies to specific geometries. Further, as Stewart says, random implies some sort of Gaussian distribution, which is not the case with turbulent flow. So the idea of randomness is not accurate--its more like we don't know.

The last cool part of this video is the dye illustration part, and how basically turbulent flow makes a blob bend and thin until it has enough of a surface area increase to go through molecular diffusion very fast. This mixing would really make sense for chemical reactions that require mixing in order to go to completion. As a chemical engineering major, this makes a lot of sense to me.

The video really helped clear up my concepts about turbulence, so definitely give it a watch! While I cannot promise the lips will be synced to the dubbing in the video, Stewart does an excellent job defining turbulence as best as possible (50 years ago).