Lengthy-time POWER readers might keep in mind Marmaduke Surfaceblow, a fictional character whose engineering escapades have been brilliantly portrayed in tons of of tales printed inside POWER journal’s pages over greater than 30 years starting in 1948. In the present day, the fictional sequence continues by means of Marmy’s granddaughter, Marnie, who’s an engineering wiz in her personal proper.
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Generally fixing one drawback causes one other or results in a series of failures that may be troublesome to diagnose. Contemplate the entire upstream and downstream impacts when altering tools and/or operations.
“Actually, now, am I anticipated to fry my behind on that?” Marnie Surfaceblow, vice chairman of Surfaceblow & Associates Worldwide, stared with disbelieving horror as she aimed Maya’s thermal imager on the rental automotive seat. “Does that truly say 115 levels Celsius or have I been pushed mad by the warmth? And since we’re in Botswana, the place is that this well-known ‘bush tea’ I maintain listening to about? Will it wake me up higher than that airline, um … espresso?”
Maya Sharma, Marnie’s lead discipline engineer, dropped her baggage within the trunk with a heavy clunk, and sighed. “Ma’am, permit me to reply in reverse sequence to your queries. First, rooibos tea, which you name ‘bush tea’ solely since you binge-watched The No. 1 Girls’ Detective Company on the flight, doesn’t include caffeine. Second, I worry you’ve got all the time been mad. Third, calibrate the digital camera’s albedo setting; the seats are probably solely 100 levels Celsius. Lastly, you sit on these, not the naked seat.” Maya brandished two beaded seat covers, tri-color patterned just like the nationwide flag, and positioned them on the seats.
Not totally trusting their efficacy, Marnie settled gingerly onto the bead-covered passenger seat, and so they quickly have been on their two-hour drive to a photo voltaic photovoltaic (PV) energy station that was having, as Marnie termed it, “a wee little bit of hassle.” After setting the cruise management on the motorway, however retaining her eyes glued to the highway, Maya requested, “Ma’am, whereas the info we obtained seems most fascinating, I’m suspecting you’ve got one more reason for us accepting this challenge?”
“Two causes,” Marnie replied cheerfully as she watched the dry savannah move by her view. “Botswana is pushing plentiful PV energy potential, virtually predestining our presence.” Maya shook her head on the epic alliteration, whereas Marnie continued. “Furthermore, the plant supervisor studied at college with my father, Man Newcomen Surfaceblow, and is virtually certainly one of our household.”
“And your needing further frequent flier miles by month’s finish to realize ‘Triple Platinum’ membership was coincidence?” Maya deadpanned.
After an uncomfortable pause, Marnie replied sotto voce, “They even offer you titanium baggage tags along with your identify in gold leaf.”
Welcome to Botswana
After a perfunctory check-in with safety, the duo parked in entrance of a small engineering constructing, apparently a repurposed former schoolhouse. Regardless of their sun shades, the scattered incidental reflections from the PV panels surrounding them have been almost blinding (Determine 1), and exceedingly sizzling, spawning mud devils between the PV panels. Aligned in neat rows and rolling up and down the encircling hills, Marnie marveled that the 20-MW plant coated simply over 400 acres (162 hectares). “A 100-MW combustion turbine would take lower than a thousandth the house,” she commented.
1. The solar was a “wee bit brilliant,” and the temperature was lots heat when Marnie and Maya arrived in Botswana. Supply: POWER
Maya nodded, “It’s a sacrifice of land, weighed towards the advantages of power independence and sustainable renewable power. The soil right here was eroded from a long time of poor farming follow; thus, this can be a good use for it.”
The mournful susurration of the wind was interrupted by a contented cry. “My goodness, is that little Marnie, all grown up now then?! Welcome to the place the solar stays to relaxation, passing on its blessings!”
The 2 girls turned to face a tall aged man wearing white enterprise apparel, leaning on a cane however with a quiet power, whose smile was a heat welcome. Three different males, wearing related apparel however with considerably wearily cautious seems, stood behind him.
“Uncle Mo-mo!” Marnie squealed with delight, operating ahead to hug the older gentleman. Virtually knocked off his ft, he laughed warmly, then chided, “Simple baby, greater than 80 years have I seen, let me see a minimum of yet another!”
Introductions have been made, with “Uncle Mo-mo” being launched as Mosegi Mosweu, the plant supervisor. The three males with him have been your entire energy station engineering group—Ashish Jain from India, Dirk Becker from Germany, and Jun Huang from China. After being hustled out of the warmth and into the considerably cooler engineering constructing, Marnie and Maya have been led to a small convention room, with tinted and dust-coated home windows overlooking the PV rows. Marnie froze all of a sudden, sniffing the air suspiciously, then broke right into a dimpled smile. “Unc … I imply, Mr. Mosweu, do I scent not mere pedestrian espresso, however the Marmaduke Household Particular Home Mix?!” Mr. Mosweu smiled additional, “Specifically imported on your pleasure, Ms. Surfaceblow.” Marnie wanted no additional encouragement, rapidly filling the most important mug that she may discover.
Exhausting-to-Clear PV Panels
The traditional enterprise ritual of the exchanging of enterprise playing cards, plugging in of laptops and telephones, and small discuss in regards to the climate ensued. Mr. Mosweu cleared his throat as a sign for everybody to return to character. Jun referred to as up a PowerPoint and related her laptop computer to a big flat-screen monitor.
Dirk took the ground first. “This energy station has operated for 2 years. The reliability is ample, however the efficiency mediocre. You’ve gotten seen the mud? It’s in all places, and the panels are coated with it. Energy output is decreased by something from 9% to 16% between cleansing actions.”
“Sir, are you able to describe how your PV cleansing system performs?” requested Maya.
Dirk stared at Maya in disbelief, shook his head and raised his palms dramatically, and scoffed “Fraulein, you didn’t learn the design paperwork we despatched?”
Mr. Mosweu began to boost a hand, however stopped as Marnie shook her head rapidly. Maya, fixing Dirk with a gimlet stare, replied steadily, “Your unique plan was utilizing demineralized effectively water on-site, however your aquifer is depressed from agriculture wants. After months with out effectively water, you modified to filtered river water. It’s delivered by 4 vehicles per day, every containing 7,500 liters of water, and I estimate you require better than 6,000,000 liters of water yearly. Your water cleansing system employs water spray at two strain ranges. Each to keep away from thermal shock and to make the most of your a lot stronger night time breezes, you use the system very late within the night. Likewise, the system begins at low strain to create a light-weight mist, then switches after 5 minutes to a water stream.”
Pausing for breath, Maya drank her tea, closed her eyes for a second, then stood up and pointed a finger on the German engineer. “What I’m asking you, sir, is for actuality. How does your system truly carry out?!”
Shocked however impressed, Dirk nodded his head. “My apologies, Fraulein. You perceive the system effectively, and positively you additionally see it requires an excessive amount of water. There’s vital overspray of many panels, and this results in excessive water prices.”
“And allow us to not neglect the impression on the river and wildlife,” added Ashish. “Additionally, just some water falls from the panels to nourish the soil. A lot evaporates as drift and is misplaced.” Turning to handle Marnie, Ashish added, “Ma’am, are you able to assist us enhance our water cleansing system?”
“What about utilizing compressed air, electrostatic, or motorized brushes?” requested Marnie, flipping by means of plant operations and upkeep data on her laptop computer.
“I’ve studied many strategies, testing on one row of panels,” replied Ashish. “Compressed air methods have required a lot auxiliary energy, and the mud could be very abrasive. The mud has excessive electrical resistivity, requiring highly effective electrostatic prices. These additionally require a lot energy, and have broken each our monitoring and management parts for the solar monitoring methods.”
“We examined rotating and sweeping brushes, and I designed a system myself,” added Dirk, shaking his head. “The abrasive ash once more scores the panels, inflicting misplaced effectivity.”
“Briefly, my baby, we search a distinct approach,” Mr. Mosweu concluded. “One thing artistic, corresponding to that one time,” he shook a playfully chiding finger towards Marnie, “when not solely did you utilize that mowing machine motor to energy your bicycle, however you fueled it along with your grandfather’s Sandpaper gin. Oh baby, he was most cross, sure?”
Marnie struggled retaining her composure, a half-smile taking part in about her lips. “He wasn’t that upset. At my college commencement social gathering, he took me apart and instructed me the misplaced gin was price seeing me stick with it the household custom.”
Maya paused from plotting knowledge on her laptop computer, and with a raised eyebrow stated, “I’m most impressed you operated a motor with a gas comprised of better than 50% water.”
Marnie shrugged. “That Sandpaper gin of his, effectively, it had a tad bit extra kick than 100 proof. Keep in mind the fireplace I instructed you about …”
“At your cousin’s Quinceañera? Sure, I’ve heard about it many occasions,” Maya replied rapidly.
A Constant Inconsistency
“I’ve learn of your nice works, and the household custom is well-bourn by you, Marnie. So, you possibly can assist your outdated Uncle Mo-mo?” Mr. Mosweu requested with an expectant smile.
2. With the assistance of summer time interns, Maya and Marnie produced color-coded satellite tv for pc plots of the photo voltaic farm based mostly on every panel’s precise energy output versus design. Supply: POWER
It was Maya who answered, however with a query. “Mr. Mosweu, and firm, now we have examined your panel design and efficiency, using many strategies, and now we have doubts about some anomalies. Might I?” requested Maya, already plugging the room projector cable into her laptop computer. The massive LCD wall show confirmed a satellite tv for pc plot of the photo voltaic fields, every panel outlined with certainly one of a number of colours (Determine 2).
“Level one: not all PV panels lose energy equally—see by the color-coding right here. The panels struggling the best loss are discovered on this slope between these two low ranges of hills, the place you’ve got terraced the land like ghats—steps,” Maya famous. “On the extra elevated aircraft there may be some variation in energy loss, however not almost on the stage seen within the downward slope and steps.”
Ashish frowned however nodded. “That can be the place now we have the best wind move at night time. You see on the backside of the slope, the place there are a number of 250-kW wind generators to make the most of that impact.”
“These wind generators have been very obliging, whispering secrets and techniques in our prepared ears that helped us discover the metaphorical thieves stealing your energy,” Marnie responded as she stood to pour her seventh cup of espresso.
Mr. Mosweu requested, “I’m curious. We’ve got almost 50,000 panels, and also you outlined every with colours? How was this completed?”
“Summer time interns, fueled by free pizzas, caffeine, and high-fructose corn syrup,” Marnie cheerfully replied. Maya gave her boss “The Look,” and stated, “You maybe shouldn’t be so completely satisfied about encouraging unhealthy dietary habits amongst youth.” She then sighed, advancing to the subsequent slide whereas muttering quietly, “Why do I say this to my boss, whose blood is a minimum of 50% espresso.”
A Masked Wrongdoer
Freshly fueled with espresso, Marnie continued. “Level 2: your energy loss doesn’t correlate with mud accumulation. Oh, I do know, it seems prefer it does, however to cite Shakespeare, ‘that which seems vital could also be solely an phantasm.’ ”
“Ma’am, that’s from the anime Cowboy Bebop, not Shakespeare,” interjected Maya. “Observe these energy output developments over the day,” she stated whereas displaying multi-colored charts. “Generally, your direct present to alternating present—DC to AC—energy inverters present the standard developments of decreased output as a perform of the ambient temperature. A query: why have been string inverters chosen, slightly than centralized inverter islands, given your peak capability is just 20 MW?”
Dirk was please to reply. “Logistics and ease of restore,” he stated. “Massive inverters are troublesome to deliver to the positioning, and few are specialised of their repairs. With extra however smaller inverters, we maintain spares in our stock, and our upkeep crew can substitute your entire unit, which is way safer and simpler than rebuilding a a lot bigger inverter.”
“Important decisions,” added Ashish, “as inverter failures listed here are a lot better than anticipated.”
Marnie nodded in settlement. “Clever selections, and so they additionally helped us discover what ought to be the issue. Maya, please present our associates the development you so cleverly seen?”
Transferring to the subsequent slide, Maya continued. “When your system was new, typical developments of decreased energy manufacturing have been famous as the positioning temperature elevated. I analyzed variables corresponding to energy output, ambient temperature, hourly cloud cowl, humidity, and lots of different elements. Once more, ambient temperature is probably the most vital variable—chances are you’ll expertise as much as 10% inverter loss on the most well liked days, however sometimes that is recovered within the late night. Adjusting for native climate, this cycle correlates at a stage of three Sigma.”
Marnie interjected with a sidebar, “Not sufficient to announce a brand new subatomic particle, such because the espresso quark, however fashionable sufficient to require a re-examination. And you understand I like to be fashionable!”
“Solely in vogue, ma’am. In any other case, you’re the antithesis of classy.” Ignoring the fake wounded innocence portrayed by her boss, Maya moved to the subsequent slide. “Level 3: your water cleansing system began operation virtually a yr late on account of your dry aquifer, however most curiously, two months after the cleansing system was on-line, your energy output on the panels within the terraced valley area declined on a a lot quicker development.”
“What is that this?” exclaimed Mr. Mosweu. “You inform me now we have made the panels dirtier by cleansing them?”
“I do know we can not tour the positioning till after sundown, because the temperature among the many panels could be lethal, however be a part of us for a stroll within the valley and we will uncover the shadow of demise to your energy system,” Maya stated.
Marnie, now on her tenth cup of espresso, broke the shocked silence by asking, “May we discuss to your electrical upkeep crew please?”
A Stroll By the Valley
It was an hour previous sundown, however photo voltaic fields have been nonetheless uncomfortably heat. Joined by a small upkeep crew, Marnie, Maya, Mr. Mosweu, and his engineering group opened a number of inverter doorways within the larger plains area, discovering little of observe. Dirk commented, “The mud can’t be stopped from getting into the inverter cooling fan ductwork. Always altering cartridge filters was extremely costly, so we designed passive inlet air filtering with impression separators, cyclones, and vortex screens. You see they work effectively, because the inverter methods have little mud.”
“And as you’ll quickly see,” added Marnie with a dramatic air, “appearances can deceive.”
Marnie led the group towards the PV panel inverter sheds within the valley area. Surprisingly, the valley sheds contained much less mud than these within the plains. “And that, Uncle, is the issue. Come, really feel the inverter cooling fan move.” Certainly, as Mr. Mosweu and his group positioned their palms in entrance of the ductwork, solely a slight breeze of air was felt. Ashish and Dirk confirmed the cooling followers have been nonetheless operating, regardless of their lackluster airflow.
However simply two rows additional down the valley, no cooling air was flowing in any of the inverter sheds. Smiling with the boldness of competence, Marnie introduced, “Have the upkeep crew open the consumption ductwork and clear it out, please?”
Fast work by the positioning upkeep crew confirmed the reason for the blocked move—dried mud crammed the consumption ducts. And such was the case with virtually each different inverter shed they inspected within the valley. Wiping the sweat from his face, Mr. Mosweu sighed, “Ms. Surfaceblow, Ms. Sharma, please clarify.”
A nudge from her boss prompted Maya to inform the story. “It’s a matter of each environmental and design issues. Working the water cleansing system at night time when the wind is quicker brings dust-laden air to mix with the water drift you expertise. This creates particles of dampened mud—some fall to the bottom, some stick on the panel surfaces, and a few are drawn into the inverter cooling fan air intakes. This phenomenon is extra prevalent within the valley, because the water drift cools the air, making it denser and extra more likely to move naturally towards decrease elevations.”
Marnie jumped in so as to add, “The dampened mud may need handed by means of your air intakes with out sticking, however tortuous paths and turbulent move out of your redesign elevated drop-out of the moist mud, slowly strangling, after which killing, the cooling move. This in flip elevated your inverter temperatures, inflicting extra energy loss for longer parts of the day, in addition to rather more frequent inverter failures. In truth, your personal upkeep crew famous making an attempt to scrub out the consumption system was rather more troublesome than altering an air filter, in order that they couldn’t commit as a lot labor towards retaining the air flowing. Maya confirmed this as effectively, performing power stability calculations, the place she famous the cooling fan amperage was a lot lower than the unique specification because of the followers stalling from the blocked inlets. The ultimate step to check the idea was affirmation by inspection.”
A Inventive Resolution
Returned to the cool of the assembly room, Mr. Mosweu sighed. “So, your suggestion is to disable every inverter in flip till we verify they’ve correct cooling, and discontinuing water cleansing till we discover a higher approach.”
“I additionally advocate, sir, that you just return to utilizing customary cartridge filters, that are easy to examine and substitute,” stated Maya. “On the long run, I like to recommend strategies now we have employed for mud discount in my dwelling nation—windbreaks, laying of stone in closely eroded areas, and discovering a species of plant that may develop, even thrive, below the panel fields with minimal water use.”
“Perhaps you might genetically engineer a hybrid of rooibos and my household’s particular espresso, and adapt it to thrive alongside along with your energy station!” Marnie exclaimed hopefully. “Then, we may open a department workplace right here. Consider it, Maya! We may create The No. 1 Girls’ Engineering Consultancy, and …”
Mr. Mosweu clapped his palms and laughed, “If that’s required to proceed such impressed options, I’m sure something is feasible!”
“We’ll keep a few days to go to, Uncle, and ship you a preliminary report by the top of the week,” replied Marnie.
“And, ma’am, don’t forget to retrieve your ‘Triple-Platinum’ baggage tags after we arrive on the airport,” Maya added slyly. Already flush from the warmth, Marnie’s blush of embarrassment was well-hidden.
—Una Nowling, PE is an adjunct professor of mechanical engineering on the College of Missouri-Kansas Metropolis.