Noor III Solar Tower of the Ouarzazate Power Station, at dusk. (Credit: Marc Lacoste)

The Future Of Energy Storage On Both Sides Of The Meter

April 13, 2022 by Maya Posch 81 Comments

That energy storage is a hot topic is hardly a surprise to anyone these days. Even so, energy storage can take a lot of different forms, some of which are more relevant to the utility provider (like grid-level storage), while others are relevant to business and home owners (e.g. whole-house storage), and yet other technologies live in this tense zone between utility and personal interest, such as (electric) vehicle-to-grid.

For utilities a lot of noise is being made about shiny new technologies, such as hydrogen-based storage, while home- and business owners are pondering on the benefits of relying solely on the utility’s generosity with feed-in tariffs, versus charging a big battery from the solar panels on the roof and using the produced power themselves. Ultimately the questions here are which technologies will indeed live up to their promises, and which a home owner may want to invest in.

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Bath County Pumped Storage Station (Credit: CHA)

Grid-Level Energy Storage And The Challenge Of Storing Energy Efficiently

April 6, 2022 by Maya Posch 118 Comments

Although every electrical grid begins with the production of electricity, there are times when storing this power in some form instead of using it immediately is highly convenient. Today’s battery-powered gadgets are an obvious example of such time-shifting, but energy storage plays a major role on the grid itself, too, whether in electrochemical, mechanical or in some other form.

Utility-level energy storage is essential for not only stabilizing the grid, but also to time-shift excess energy and provide a way to deal with sudden spikes in demand (peak-shaving) plus demand drops by absorbing the excess energy. The health of the grid can essentially be regarded as a function of its alternating current (AC) frequency, with strong deviations potentially leading to a collapse of the grid.

Naturally, such energy storage is not free, and the benefits of adding it to the grid have to be considered against the expense, as well as potential alternatives. With the rapid increase of highly volatile electrical generators on the grid in the form of non-dispatchable variable renewable energy, e.g. wind turbines and PV solar, there has been a push to store more excess power rather than curtailing it, in addition to using energy storage for general grid health.

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Circuit VR: The Wheatstone Bridge Analog Computer

March 31, 2022 by Al Williams 13 Comments

We are always impressed with something so simple can actually be so complex. For example, what would you think goes into an analog computer? Of course, a “real” analog computer has opamps that can do logarithms, square roots, multiply, and divide. But would it surprise you that you can make an analog device like a slide rule using a Wheatstone bridge — essentially two voltage dividers. You don’t even need any active devices at all. It is an old idea and one that used to show up in electronic magazines now and again. I’ll show you how they work and simulate the device so you don’t have to build it unless you just want to.

A voltage divider is one of the easiest circuits in the world to analyze. Consider two resistors Ra and Rb in series. Voltage comes in at the top of Ra and the bottom of Rb is grounded. The node connecting Ra and Rb — let’s call it Z — is what we’ll consider the output.

Let’s say we have a 10 V battery feeding A and a perfect voltmeter that doesn’t load the circuit connected to Z. By Kirchoff’s current law we know the current through Ra and Rb must be the same. After all, there’s nowhere else for it to go. We also know the voltage drop across Ra plus the voltage drop across Rb must equal to 10 V. Kirchoff, conservation of energy, whatever you want to call it. Let’s call these quantities I, Va, and Vb. Continue reading “Circuit VR: The Wheatstone Bridge Analog Computer” →

Tech In Plain Sight: Car Doors

March 24, 2022 by Al Williams 54 Comments

There are a lot of common phrases that no longer mean what they used to. For example, you may have used the term “turn on the lights.” What are you actually turning? Where does this come from? Old gas lights had a valve that you did physically turn, and the phrase simply stuck around. Kids of the 90s have no idea why they “dial” a phone number. What about “roll up the car window”? You don’t often encounter old-fashioned car doors with manual locks or a crank to roll up the window. These days it is all electronic. But have you ever wondered what’s going on inside there?

Let’s take a look at car doors, how they keep you safe, and how that sheet of glass slides into place, sealing against wind, rain, and noise. Of course, there are fancy car doors like suicide doors or sexy-but-impractical gull wing doors. At least one concept car even has a door that disappears under the vehicle when it opens; check out the video below. But even garden-variety doors are marvels of mechanical engineering. A compact structure that is secure and — mostly — reliable. Let’s look at how they do that.

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3D Printing Concept Car (Parts)

March 23, 2022 by Al Williams 6 Comments

When you want to fabricate something you either start with something and take away what you don’t want — subtractive manufacturing — or you start with nothing and add material, which is additive manufacturing that we usually call 3D printing. Popular Science recently took a look inside Vital Auto, the British lab that uses 3D printing for high-end concept cars from companies like Rolls-Royce, McLauren, Jaguar, and others. In the video below, [Anthony Barnicott], an engineer for Vital, says that the two technologies — additive and subtractive — work best when used together.

As you might expect, they are not using a $200 FDM printer. They have three Formlabs 3Ls that print with resin and five Formlab Fuse 1 selective laser sintering printers. While metal printers are still uncommon in hacker’s workshops, resin printers are now very affordable although your garage printer is probably a good bit smaller than the 3L’s 335x200x300 mm volume. For comparison, an LCD-based AnyCubic Photon X provides just 165x132x80 mm. Of course, you’re looking at about $11,000 for the dual-laser 3L versus about $240 for the Photon.

Vital started building the EP9 electric car concept for NIO, an electric car maker in China. You can imagine that modern manufacturing machines make it possible to create more sophisticated concept cars faster. How many times do you want to tweak a part that takes a machinist eight hours to produce? But if you can just let a machine run overnight and get the result in the morning, you are more likely to change and refine the part.

Vital Auto is an interesting look at how professional fabrication shops are using the same technologies we do, at least at the core. We’ve noted before how these same technologies are making homebrew projects look better than some commercial products not long ago. You can print big things if you break them up, of course. Or, break the bank and buy a really big printer.

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Ion Thrusters: Not Just For TIE Fighters Anymore

March 3, 2022 by Zoe Skyforest 42 Comments

Spacecraft rocket engines come in a variety of forms and use a variety of fuels, but most rely on chemical reactions to blast propellants out of a nozzle, with the reaction force driving the spacecraft in the opposite direction. These rockets offer high thrust, but they are relatively fuel inefficient and thus, if you want a large change in velocity, you need to carry a lot of heavy fuel. Getting that fuel into orbit is costly, too!

Ion thrusters, in their various forms, offer an alternative solution – miniscule thrust, but high fuel efficiency. This tiny push won’t get you off the ground on Earth. However, when applied over a great deal of time in the vacuum of space, it can lead to a huge change in velocity, or delta V.

This manner of operation means that an ion thruster and a small mass of fuel can theoretically create a much larger delta-V than chemical rockets, perfect for long-range space missions to Mars and other applications, too. Let’s take a look at how ion thrusters work, and some of their interesting applications in the world of spacecraft!

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Remembering The MIT Radiation Laboratory

February 7, 2022 by Chris Lott 32 Comments

Back in the late 80s, our company managed to procure the complete 28 volume MIT Radiation Laboratory (Rad Lab) series, published in 1947, for the company library. To me, these books were interesting because I like history and old technology, but I didn’t understand why everyone was so excited about the acquisition. Only a cursory glimpse at the volumes would reveal that the “circuits” these books described used vacuum tubes and their “computers” were made from mechanical linkages. This was the 1980s, and we worked with modern radar and communications systems using semiconductors, integrated circuits, and digital computers. How could these old musty books possibly be of any practical use? To my surprise, it turned out that indeed they could, and eventually I came to appreciate the excitement. I even used several of them myself over the years.

Radiation Lab? Nuclear Radar?

In the years leading up to WW2, the idea of a civilian organization of scientists that would operate independently of the military and government bureaucracies was being championed by Dr. Vannevar Bush. The military and scientists had not worked well together during the first World War, and it looked like science and technology would be playing a much bigger role in the future.

It seemed certain that America would enter the conflict eventually, and Dr Bush and others believed that a new organizational framework was called for. To that end, the National Defense Research Committee (NDRC), which later became the Office of Scientific Research and Development (OSRD) was pitched to President Roosevelt and he approved it in June of 1940.

Almost immediately, a gift fell in the lap of the new organization — the Tizard Mission which arrived in the states from the UK in Sep 1940. They brought a literal treasure chest of technical innovations from the British, who hoped that US industry’s cooperation could help them survive what looked like certain and imminent invasion. One of those treasures was the cavity magnetron, which our own Dan Maloney wrote about a few years ago.

Within a few weeks, under the guidance of young Welshman “Taffy” Bowen, they had reviewed the design and gathered up the necessary equipment to fire it up. A 10 kV anode power supply and a 1,500 gauss electromagnet were procured, and the scientists gathered at the Bell Radio Laboratories in Whippany New Jersey on Sunday, Oct. 6, 1940. They powered up the cavity magnetron and were blown away by the results — over 10 kW of RF at 3 GHz (10 cm) from something the size of a bar of soap. Continue reading “Remembering The MIT Radiation Laboratory” →