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crapfutures · 7 years

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Back to nature

We live on a remote island - mountainous, mid-Atlantic, still heavily forested and pretty wild - and for that reason nature sometimes sneaks into our otherwise technology-centred work. It is hard not to think local when you live in a place like this. We’re neither farmers nor pioneers - except in the sense that resident aliens on this island are few - but lately our reading has got us thinking about ancient paths and rural places. We’ll discuss the paths today and save most of the farm talk for a future post.

Paths v roads

In his 1969 essay ‘A Native Hill’, Wendell Berry - the American writer, farmer, activist, and ‘modern Thoreau’ - makes a useful distinction between paths and roads:

The difference between a path and a road is not only the obvious one. A path is little more than a habit that comes with knowledge of a place. It is a sort of ritual of familiarity. As a form, it is a form of contact with a known landscape. It is not destructive. It is the perfect adaptation, through experience and familiarity, of movement to place; it obeys the natural contours; such obstacles as it meets it goes around. A road, on the other hand … embodies a resistance against the landscape. Its reason is not simply the necessity for movement, but haste. Its wish is to avoid contact with the landscape. … It is destructive, seeking to remove or destroy all obstacles in its way.

Aside from conversation as usual, the reason we are talking about Berry is the arrival of a new film, Look & See, and a new collection of his writing, The World-Ending Fire, edited by Paul Kingsnorth of Dark Mountain Project fame. Berry and Kingsnorth, along with the economist Kate Raworth, were on BBC Radio 4’s Start the Week recently chatting about the coming apocalypse and how it might best be avoided. It is a fascinating interview: you can actually hear Berry’s rocking chair creaking and the crows cawing outside the window of his house in Port Royal, Kentucky.

The normally optimistic Berry agrees somewhat crankily to read ‘the poem that you asked me to read’ on the programme. ‘Sabbaths 1989’ describes roads to the future as going nowhere: ‘roads strung everywhere with humming wire. / Nowhere is there an end except in smoke. / This is the world that we have set on fire.’ Berry admits that this poem is about as gloomy as he gets (‘blessed are / The dead who died before this time began’). For the most part his writing is constructive: forming a sensual response to cold, atomised modernity; advocating for conviviality, community, the commonweal.

Paul Kingsnorth talks compellingly in the same programme about transforming protest into action, although in truth no one walks the walk like Berry. Kingsnorth says: ‘We're all complicit in the things we oppose’ - and never were truer words spoken, from our iPhones to our energy use. In terms of design practice, there are worse goals than reducing our level of complicity in environmental harm and empty consumerism. Like Berry, Kingsnorth talks about paths and roads. He asks: ‘Why should we destroy an ancient forest to cut twelve minutes off a car journey from London to Southampton? Is that a good deal?’

It’s a fair question. It also illustrates perfectly what Berry was describing in the passage that started this post: the difference between paths that blend and coexist with the local landscape, preserving the knowledge and history of the land, and roads that cut straight through it. These roads are like a destructive and ill-fitting grid imposed from the centre onto the periphery, without attention to the local terrain or ecology or ways of doing things - both literally (in the case of energy) and figuratively.

Another book we read recently, Holloway, describes ancient paths - specifically the ‘holloways’ of South Dorset - in similar terms:

They are landmarks that speak of habit rather than of suddenness. Like creases in the hand, or the wear on the stone sill of a doorstep or stair, they are the result of repeated human actions. Their age chastens without crushing. They relate to other old paths & tracks in the landscape - ways that still connect place to place & person to person.

Holloways are paths sunk deep into the landscape and into the local history. Roads, in contrast, skip over the local - collapsing time as they move us from one place to the next without, as it were, touching the ground. They alienate us in our comfort.

Here in Madeira there are endless footpaths broken through the woods. Still more unique are the levadas, the irrigation channels that run for more than two thousand kilometres back and forth across the island, having been brought to Portugal from antecedents in Moorish aqueduct systems and adapted to the specific terrain and agricultural needs of Madeira starting in the sixteenth century.

Both the pathways through the ancient laurel forests and the centuries-old levadas (which, though engineered, were cut by hand and still follow the contours and logic of the landscape) contrast with the highways and tunnels that represent a newer feat of human engineering since the 1970s. During his controversial though undeniably successful reign from 1978 to 2015 - he was elected President of Madeira a remarkable ten times - Alberto João Jardim oversaw a massive infrastructure program that completely transformed the island. Places that used to be virtually unreachable became accessible by a short drive. His legacy, in part, is a culture of automobile dependency that is second to none. The American highway system inspired by Norman Bel Geddes’ (and General Motors’) Futurama exhibit at the 1939 New York World’s Fair almost pales in comparison to Jardim’s vision for the rapid modernisation of Madeira.

But when you walk the diesel-scented streets of the capital, or you drive through the holes bored deep into and out of towering volcanic mountains to reach the airport - and even when you think back in history and imagine those first settlers sitting in their ships as half the island’s forest burned, watching the dense smoke of the fires they lit to make Madeira favourable to human habitation - it’s hard not to think what a catastrophically invasive species are human beings.

Bespoke is a word we use a lot. In our vocabulary bespoke is not about luxury or excess - as it has been co-opted by consumer capitalism to suggest. Instead it is about tailored solutions, fitted to the contours of a particular body or landscape. Wendell Berry insists on the role of aesthetics and proportionality in his approach to environmentalism: the goal is not hillsides covered in rows of ugly solar panels, but an integrated and deep and loving relationship with the land. This insistence on aesthetics relates to the ‘reconfiguring’ principles that inform our newest work. The gravity batteries we’ve been building are an alternative not only to the imposed, top-down infrastructure of the grid, but also to the massive scale of such solutions and our desire to work with the terrain rather than against it.

Naomi Klein talked about renewable energy in these terms in an interview a couple of years ago:

If you go back and look at the way fossil fuels were marketed in the 1700s, when coal was first commercialized with the Watt steam engine, the great promise of coal was that it liberated humans from nature … And that was, it turns out, a lie. We never transcended nature, and that I think is what is so challenging about climate change, not just to capitalism but to our core civilizational myth. Because this is nature going, ‘You thought you were in charge? Actually all that coal you’ve been burning all these years has been building up in the atmosphere and trapping heat, and now comes the response.’ … Renewable energy puts us back in dialog with nature. We have to think about when the wind blows, we have to think about where the sun shines, we cannot pretend that place and space don’t matter. We are back in the world.

In a future post we will talk about the related subject of sustainable agriculture. But speaking of food - the time has come for our toast and coffee.

Images: Wendell Berry courtesy of Look & See; all others via Wikimedia Commons

#gravity battery #renewable energy #speculative design #wendell berry #naomi klein

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inexcon · 5 years

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RSI Comm-Link: Galactic Guide: Kallis System

This Galactic Guide originally appeared in Jump Point 5.2.

A Star Is Born

A whirling mass of potential, the recently discovered Kallis system has excited scientists and researchers the Empire over by offering them a rare opportunity: to witness the formation of a stellar system first hand.

Kallis was first visited in 2921 through its jump point connection with Oso, and initial ICC scans of the system revealed a G-class main sequence star anchoring nine protoplanets in various stages of development. Officially, the system’s discovery is credited to OB Station Chimera, the main research facility in Oso, but many still persist that it should be rightly attributed to former PFC Gabby Rifon.

Part of the Army security force detailed under the Fair Chance Act to protect Oso II from poachers, smugglers, and other trespassers, Rifon served as a long-range scan technician tasked with sweeping the system for errant ships. According to later interviews, Gabby was often “bored as hell” looking for ships hours at a time. Instead she would shrug off her duties and adjust the scan station to search for spatial anomalies. It was during one such unauthorized session that Gabby excitedly noted faint indications of a jump point. Informing her commanding officer of the discovery brought to light the fact that Gabby had been “wasting” hours during her shift. A week before the first ship would traverse the Oso-Kallis jump point, Gabby was dishonorably discharged for improper use of Army resources.

A Second Chance

Almost immediately, it was clear that Kallis (meaning “beloved” in a Martian dialect) was a system to be cherished. Once again, Humanity was getting a chance to witness the birth of a solar system firsthand, and scientists around the Empire pledged to not let the opportunity be squandered as it had been in Gurzil.

When Gurzil, a system still in its accretion phase, was discovered in 2539, scientific access was cut short due to security concerns. Upon the arrival of Xi’an ships in 2542, Gurzil was drafted into the UPE’s recently created Perry Line and set aside to protect Humanity’s borders. For the next several centuries, the system was off-limits to everyone but military forces.

Upon the dissolution of the Perry Line, the scientific community hoped that Gurzil would fall under the protection of the Fair Chance Act. However, various industries lobbied that centuries of military intervention had already damaged the system past its original scientific value and that it would better serve the credit-strapped Empire harvested of its valuable resources. In the end, the Senate voted against applying the Fair Chance Act to Gurzil and decided to allow both research and restricted mining in the system.

The scientific community was strongly motivated to make Kallis a different story.

A Front Row Seat

Within a month of the first scan report from Kallis being released, a bill was introduced on the Senate floor to place the system under the protection of the Fair Chance Act and, this time around, thanks to the pristine status of the system as well as a much more favorable Transitionalist-controlled chamber, the vote passed. The system at once became off-limits to commercial development and general traffic. From that point on, Kallis would be a sanctuary for research and discovery.

Under the guidance of a joint Army and Imperial Science and Technology Foundation governing body, the past two decades have already greatly expanded our knowledge and understanding of the universe around us. Undoubtedly, this is just the start of a trend that will continue for decades to come as research continues in Kallis around the clock and new generations of scientists eagerly await their turn to study nature’s mysteries first hand.

Kallis I

A loose fusion of recently merged planetary embryos, this small developing protoplanet has an aggressively eccentric orbit that has many researchers speculating whether it will break apart before it can establish itself.

Kallis Belt Alpha

As the gravity wakes from the nearby forming worlds tug at this dense orbiting collection of planetesimal, frequent collisions can cause chaotic motion and hazardous travel conditions anywhere nearby.

Kallis II & III

These two rocky terrestrial worlds are currently sharing an orbit, but it is estimated that one of the worlds will eventually pull in enough mass from the surrounding asteroid belts to “win the race” and subsume its sibling.

Kallis Belt Beta

A swirling mass of asteroids and dust grains, this belt is composed of materials with high melting points. Although there is enough mass here to compose three to five planets, orbital resonance with the surrounding worlds has prevented this from happening yet.

Kallis IV, V, VI

These three terrestrial worlds hold special interest for researchers as they have the greatest chance for the potential to one day support life. Kallis IV in particular has a striking resemblance to what many believe Earth must have looked like in its infancy. With active volcanoes possibly forming an atmosphere, researchers are looking into creating monitoring methods capable of lasting the lifetimes it will take to see it form. While Kallis V may not currently have any potential for developing an atmosphere, the swirl of debris orbiting its rocky surface indicates that it may soon have a series of moons to call its own. The least developed of the three, Kallis VI has a surface entirely composed of molten rock, giving it a planetary glow.

OB Station Gryphon

Located near the Kallis-Oso jump point, OB Station Gryphon was sealed late in 2922 and has served as the main operational hub for the entire system ever since. In order to preserve the living experiment that is Kallis and its protoplanets, construction throughout the rest of the system has been extremely limited. While there are small observation posts and scan satellites positioned throughout the system, if you are looking to refuel or restock, Gryphon is your only choice. All deliveries to the system are also routed through the station to ensure that the strict Fair Chance Act protocols are followed.

Despites the system’s focus on serious scholastic pursuits, it has begun to gain notoriety for the unique community that has developed over the years. Between the Army personnel stationed here to guard the system and the young grad students conducting research, the median age of the system’s small population is well under thirty. It is no wonder that the habitation decks can get a bit raucous as researchers (looking to blow off steam after days spent alone in remote obervational outposts) and soldiers (with extra energy after long shifts spent patrolling for trespassers) meet for drinks and heated debates. Toss into the mix a growing number of philosophers and spiritualists who have come seeking deeper truths about the universe’s origins, and you can see why OB Station Gryphon is a destination that’s not quite like anywhere else in the Empire.

Kallis VII & VIII

Located out beyond Kallis’ frost line, the system’s two giants formed from volatile icy compounds and captured hydrogen and helium. Kallis VII has drawn its fair share of exoclimatologists interested in studying its burgeoning storm systems, while Kallis VIII has proven exciting for those seeking to construct a more complete model regarding dynamics and chemistry in ice giant atmospheres.

Kallis IX

A small planetesimal in distant orbit around the sun, Kallis IX has the distinction of being the only celestial body in the system whose surface has been marred by orbital mining lasers, thanks to a joint UEE project with mining conglomerate Shubin Interstellar’s research department seeking to better understand this dwarf planet’s role in the system’s formation.

TRAVEL WARNING

All ships arriving in-system are expected to first stop at OB Station Gryphon to officially register. Traveling anywhere without having acquired the proper clearance is a sure way to draw the ire of the Army pilots on patrol here.

HEARD IN THE WIND

“I learned a ton during my two years in Kallis. Unfortunately, I forgot most of it thanks to my two years visiting Gryphon.”

– Dr. Wahid Allimon, Professor of Geology, University of Rhetor, 2945

“Even though my mom didn’t get the credit she deserved for discovering the system, there is some small consolation in that they named that station after her. Sure, if you ask they’ll say it’s named for one of those lion-bird things, but come on, it’s pretty clear that the scientists in charge were sticking it to those Army guys when they chose the name.”

– Alice Thomas, daughter of Gabby Rifon, 2943

http://bit.ly/2WK7vgl

#RSI.CommLink.Repost

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starcitizenprivateer · 5 years

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Galactic Guide: Kallis System

This Galactic Guide originally appeared in Jump Point 5.2.

A Star Is Born

A Second Chance

The scientific community was strongly motivated to make Kallis a different story.

A Front Row Seat

Kallis I

Kallis Belt Alpha

Kallis II & III

Kallis Belt Beta

Kallis IV, V, VI

OB Station Gryphon

Kallis VII & VIII

Kallis IX

TRAVEL WARNING

HEARD IN THE WIND

“I learned a ton during my two years in Kallis. Unfortunately, I forgot most of it thanks to my two years visiting Gryphon.”

– Dr. Wahid Allimon, Professor of Geology, University of Rhetor, 2945

– Alice Thomas, daughter of Gabby Rifon, 2943

#star citizen #squadron 42

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sad-ch1ld · 5 years

Link

via RSI Comm-Link

This Galactic Guide originally appeared in Jump Point 5.2.

A Star Is Born

A Second Chance

The scientific community was strongly motivated to make Kallis a different story.

A Front Row Seat

Kallis I

Kallis Belt Alpha

Kallis II & III

Kallis Belt Beta

Kallis IV, V, VI

OB Station Gryphon

Kallis VII & VIII

Kallis IX

TRAVEL WARNING

HEARD IN THE WIND

“I learned a ton during my two years in Kallis. Unfortunately, I forgot most of it thanks to my two years visiting Gryphon.”

– Dr. Wahid Allimon, Professor of Geology, University of Rhetor, 2945

– Alice Thomas, daughter of Gabby Rifon, 2943

#RSI Comm-Link #star citizen #roberts space industries

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caseinpoints · 7 years

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Why is global maximum power point tracking important in solar modeling?

David Bromberg, senior scientist at Aurora Solar

By: David Bromberg, senior scientist at Aurora Solar

Blog originally published on Aurora Solar

When modeling how much energy a solar design will produce, there are many features of the components that must be taken into account to ensure an accurate estimate. One important factor that modeling software must account for in order to avoid over- or under-estimating the system’s energy production is whether or not the inverter(s) used are capable of “global maximum power point tracking.” In this post, we will examine what global maximum power point tracking means—and why accounting for it is so important.

Understanding current-voltage and power-voltage curves

The datasheet of a solar panel includes a variety of data that allow one to understand the basic parameters of the device and to mathematically model its behavior within an electrical circuit. Typically, this will include graphs that illustrate the panel’s “current-voltage curve”—also known as an IV curve, for the standard abbreviations for current (I) and voltage (V) in mathematical equations—and “power-voltage curve.”

These graphs illustrate relationships between three electrical characteristics: current, voltage, and power. Power is the rate, per unit time, at which electrical energy is transferred by an electric circuit. Current (I) is the rate at which charge is flowing through the circuit, while voltage (V) is the difference in electric potential energy between two points (e.g., the output wires of a solar panel) per unit electrical charge.

A common example used to explain these principles is to think of electricity like water in a tank; the pressure in the tank is analogous to the voltage, while current would be the flow of water out of the tank (Figure 1). The IV curve shows how the panel output current varies with panel output voltage. The power-voltage curve shows how panel output power (the product of the output current and output voltage) varies with panel output voltage.

Figure 1: The concepts of voltage and current as illustrated by the example of water in a tank.

Looking at the power-voltage curve allows us to determine the point (or points) at which the panel’s power output is maximized. On the IV curve, two values that are often indicated are “Vmp” and “Imp”—which indicate the levels of voltage and current at which the solar panel’s output power is maximized under standard test conditions (STC). Nothing about the panel itself dictates that it must operate at maximum power, however; any point along the IV curve is a valid operating point. In designs using string inverters, it is the inverters that “choose” the operating point. The ability of the inverters to locate the operating point of a solar array at which output power is maximized is referred to as maximum power point tracking (MPPT).

If the solar array comprises identical solar panels operating under the same irradiance and at the same temperature—such that each constituent module has the same IV curve and maximum power point—the net IV curve of the entire array (which takes into account the IV curves of each individual module) will have a shape like the blue curve in the left half of Figure 2 below. The green curve shows the output power of the array as a function of output voltage; note that there is a single peak in power, occurring at the “knee” of the IV curve. The inverter will seek out this one point at which array power is maximized.

Accounting for shade: The role of bypass diodes

When parts of the array are shaded, however, determining the IV curve is much more complicated. The IV curves of the shaded modules are different than those of the unshaded modules, especially in regard to how much current the shaded modules can output. When the amount of irradiance on a module is low, the power of the entire string connected to the module can drop. This is due to the fact that the current through the string can only be as high as the current through the most shaded module.

To help mitigate these effects, manufacturers integrate bypass diodes into their modules. A bypass diode can be thought of as an on/off switch, which conducts any amount of current when it is “on” and, conversely, cannot conduct current when it is off. A diode has much less resistance than a shaded module, so when the diode is turned on, it effectively shorts out the shaded module by routing the string current through the diode (and around the module) rather than through the shaded solar cells.

Because bypass diodes allow the inverter to “skip over” shaded panels instead of operating at their lower current, the IV curve of an array that is partially shaded will look different than that of an unshaded array. The resulting IV curve may look like the blue curve on the right in Figure 2, with a corresponding power-voltage curve shown in green. As you can see, there are two distinct operating points at which power is “maximized” – a global maximum where the array operates at a higher current and lower voltage, and a local maximum where the array operates at a lower current and higher voltage. The global maximum occurs when the shaded modules are bypassed, and the local maximum occurs when the shaded modules are not bypassed.

Figure 2: (left) Current-voltage (blue) and power-voltage (green) curve of a solar array with no shading; (right) current-voltage (blue) and power-voltage (green) curve of a solar array with shading, where the activation of bypass diodes results in multiple possible maximum power points.

Global MPPT refers to the ability of an inverter to sweep the full IV curve of the solar array and find the operating voltage at which the global maximum power point occurs. How often the inverter sweeps the curve, and the resolution at which it does so, is generally manufacturer- and model-specific.

Importantly, not all inverters perform global MPPT. Some inverters are limited to only search for the maximum power point in a local region where it “usually” lies, a high voltage solution where no modules are bypassed. This can be beneficial for sites where there is no shading, because whenever the inverter is sweeping the IV curve searching for the maximum power point it is not actually operating at the maximum power point, and thus not producing as much energy as it could. If the maximum power point is not going to vary much because there is no shade and no reason to activate bypass diodes, then there is no reason to sweep the entire IV curve. Most modern residential inverters are capable of global maximum power point tracking because shading due to trees and obstructions is common and expected. Large commercial inverters and central inverters, however, may not have this functionality because it is generally assumed there will not be much shading.

Modeling global maximum power point tracking

If your design includes a string inverter with global MPPT functionality, it is critical that the simulation tool you use to model the system accurately represents that behavior. Consider the residential design in Figure 3, which includes two parallel strings connected to an input of an inverter and a third string connected to another input. The irradiance map (left) and 3D model (right) clearly show the effects of shade on this site. Of particular concern are the chimney on the southeast-facing roof plane and the large tree to the west of the house, both of which cast shade on several panels in the design at various times throughout the year. If we simulate this design without global MPPT, the annual production is 5.94 MWh. However, if the inverter actually does perform global MPPT, and we simulate it accordingly, the production estimate increases to 6.25 MWh (Table 1).

Figure 3: 2D view and irradiance map (left) and 3D view (right) of a residential design with shading from a chimney and tree, produced by Aurora software.

Table 1: Annual energy production for a residential design with and without global maximum power point tracking.

Given the results shown in Table 1, it is clear that knowing when to model global MPPT is just as important as being able to model it at all. Assuming every inverter has this functionality is dangerous, because it could lead to severely underperforming systems post-install. Assuming no inverter has this functionality can be a costly mistake as well, because it may lead the designer to install a larger system size than necessary.

This is why Aurora has worked with leading inverter manufacturers to confirm exactly which inverter models perform global MPPT. If a design includes an inverter with this functionality, Aurora will automatically model it. Aurora will even model global MPPT and bypass diodes down to the cell string-level, including the power losses in the diodes themselves. If Aurora has not confirmed that an inverter has global MPPT, or that an inverter only performs local tracking, this behavior will not be modeled. The performance simulation logs will indicate whether or not the simulation applied global MPPT. In this way, designers can be sure they are getting simulation results that are as accurate as possible given what is known about the equipment in their designs.

Takeaways

Global MPPT allows an inverter to sweep the IV curve of a solar array to find the point at which output power is maximized, even under partial shading.

We found a difference of over 5% in annual production when simulating a design with an inverter that has global MPPT versus one without it.

Aurora has worked with leading inverter manufacturers to confirm which models apply global MPPT and automatically simulates this behavior for those inverters.

David Bromberg is a Senior Scientist at Aurora Solar, where he leads the modeling and computational efforts that underlie Aurora’s advanced performance simulation engine. Before joining Aurora he was a research scientist at Carnegie Mellon University, where he developed new models and algorithms for robustly simulating transmission and distribution power grids. He received the B.S., M.S., and Ph.D. degrees, all from Carnegie Mellon, in 2010, 2012, and 2014, respectively.

Solar Power World

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