Tag: power

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Analog Electronics Renewable Energy

What the heck is a Smart Grid? (Part 1)

First off, a smart grid does not yet exist. It’s not exactly dumb, but it’s unwieldy and needs some help getting itself under control.

So let’s think of the electricity grid as an elephant.

It’s big, it’s powerful and it takes a ton of work to get it moving in one direction or another. It’s also really expensive to get it from one place to another. If you want to move an elephant over a distance of hundreds of miles, it’s going to want some peanuts, after all.

A Smart Grid in this analogy is the trainer that controls the elephant.  The consumer is a person off in the distance, holding a peanut. And elephants love peanuts, so they will naturally go where they are. The trainer might be able to guide the elephant towards the people willing to pay the most peanuts. The trainer might also be able to tell the consumer to save their peanuts because getting the elephant at certain times of days will be expensive. And for the health of the elephant, he can say “enough is enough” and start to scale back how many peanuts the elephant is really allowed to eat that day. In the end though, the trainer is only guiding the elephant. The things that truly are controlling the elephant are how much energy he has and how many peanuts people are willing to offer him.

So how does an elephant relate back to the actual power grid? Well, think of a typical coal power plant. The coal is used to heat water, the water turns to steam, the steam turns a turbine and then the water is cooled and recycled to be used for another cycle. The AC power is distributed to transformers that step up the voltage of the signal to thousands of volts before the power is pushed through transmission lines. When you flip a switch in your house, you allow current to flow into whatever device is “requesting” power, thereby utilizing some small portion of the total energy on the grid. Now, if there were 10,000 people trying to turn on their clothes dryers simultaneously, the system will likely not be able to keep up. More power stations could come online, but the instantaneous need would instead likely cause blackouts and brownouts to occur, leaving customers without power. So what they do is try to curb everyone turning on their clothes dryer at the same point every day by charging a lot of money for using the power then. They say, “Why not run the dryer at night? We’ll make it worth your while!”. The Smart Grid/Trainer is there to try and balance the needs of the consumer and the ability of the power generators. It will hopefully save people money and allow power generation facilities to avoid turning to readily available energy (coal, natural gas) to fulfill the demand.

A smart grid has a potential to bring a lot of engineering jobs, especially in waning job markets such as the US. I plan to write more about the Smart Grid because I truly believe it will bring some innovation and employment to whoever jumps on the technology first. There are a lot of pieces to the eventual solution–some more interesting than other–but all deserve analysis and consideration in determining what will result in the most efficient eventual system.

Do you know much about the Smart Grid? Have you experienced any development or funding activities for it yet? Please let us all know in the comments!

Thanks to exfordy for the photo

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Blogging Economics Music Politics Renewable Energy

“Hot, Flat and Crowded” By Thomas Friedman — A short review

I love public libraries because it’s like having Amazon.com minus the pesky notion of paying for a book. However, the downside is you don’t get to keep what you’re reading–especially if it is a popular book that other people want before you can renew it. As such, I’m going to review what I’ve read of this book so far, because it’s just that good.

For background, Thomas Friedman also wrote “The World is Flat”, a book detailing how the economy and the world has changed since the September 11th attacks, both good and bad. In that book (written in 2005) he details the benefits of outsourcing and globalization and actually downplays the notion of globalization as an enemy, instead framing it as an opportunity that requires a competitive nature in workers and corporations. While that book was written before there was the possibility of recession, the book explains the rapid growth that is occurring overseas which will likely collapse along with the credit markets. I highly suggest reading that book if you have not, it is a great introduction into Friedman’s writings and is a good preface for the book reviewed here.

Onto the main event. Let’s decode the title of this book:

  • Hot — Not too hard to figure this one out. Global warming is not just a potential threat anymore, it’s real, it’s dangerous and it’s here to stay (or is it?)
  • Flat — See the previous paragraph. The world is quickly trying to elevate more people into the middle class than ever before. This is putting a serious strain on all resources of the planet, including the atmosphere.
  • Crowded — Barring a major war, outbreak or famine, the world population keeps on growing. Add to the mix better drugs, a higher focus on health and longer life expectancies, the people that are here will probably stick around too. Overpopulation is yet another drain and strain on the planet’s resources, multiplicatively so if those people are in the middle class.

Of these, I would put forth that only the “hot” portion has any solution, and at that, reduced consumption and switching to renewable energy will likely only go as far as retaining the current temperature of the earth. For the “flat” and “crowded” parts, the best case scenario is that we find ways to accommodate more and more people entering the middle class and the world in general by changing our perceptions of allowable consumption in the middle class (and any class for that matter). Most notably, Americans who have become accustomed to a particularly wasteful way of life (as chronicled by Duncan)may have to re-assess how they consume products; while it would be nice to think we will do this with conservation in mind, more realistically we will be forced to do this because of the laws of supply and demand are going to make previously cheap products much more expensive.

How do we do it, you ask? With a “green revolution”. This means an economy that is based around locally produced energy that is both renewable and environmentally friendly. Even though it sounds a bit new-agey to conjecture that renewable energy can save the world, it really starts to make sense when you look at current world issues. Here are some problems that a green economy can fix:

  1. Energy supply and demand — The best ways to bring down energy costs is to either flood the market with it (energy) or tell the energy producers you don’t need it. Since the world as a whole will not likely give up our digital and analog electronic gadgets anytime soon and our energy usage will likely increase, it would behoove us to begin making cheap and renewable energy. Since oil doesn’t seem to be an option as cheap energy anymore, we should probably start looking at new exciting options, like solar cells made out of black silicon.
  2. Petropolitics — If we don’t end up going out and figuring out how to make renewable energy, we’ll continue shipping boatloads of money to countries that hate us. Like I had written about these oil barons before, why not hit them where it hurts? In the wallet.
  3. Climate Change — Al Gore knows it and told a lot of the world. There is undeniable climate change happening every day we continue to dump greenhouse gases into the atmosphere. Reduce coal and oil usage and the amount we dump into the air will go down.
  4. Energy Poverty — Without energy, it’s hard to do a lot of things. Most of us would go check into a hotel if the power went out for more than a week. However, one third of the world lives in energy poverty, meaning they cannot even come close to pulling themselves out of monetary poverty; health standards are proven to drop dramatically when people live this way.
  5. Biodiversity Loss — Human consumption of natural resources is threatening damn near every species on the planet, up to and including humans. If we don’t want to have only cockroaches and squirrels running around a polluted planet with us, we need to set up more sanctuaries and reduce

I unfortunately didn’t get to read about all of Friedman’s ideas, but plan to read more as I get my own copy of this book. (More of the basis of his ideas can be read from his entries in the NY Times and Foreign Policy magazine)

I will leave you with one of my favorite statistics and quotes that Friedman puts in the (beginning of the) book; Moisés Naím also writes in Foreign Policy about the Chinese and Indian middle class that is emerging and how “the total population of the planet will increase by about 1 billion people in the next 12 years, [but] the ranks of the middle class will swell by as many as 1.8 billion”. Just think about that for a second. 1.8 BILLION more people leaving the lights on, eating cheeseburgers, driving SUVs and doing everything else they’ve been sold as “the American Dream” (or at least way of life). They can’t be stopped and they are constantly told through advertising that they deserve whatever they want. Something has to change, and fast (besides the economy). I want to find solutions for new renewable energy and I hope you do too; but a quick thing that will help everyone is if you switch those lights off at home when you’re not using them, so be sure to do that too.

Scared by all of this? That wasn’t the point of this post, but it scares the heck out of me too. Go out and read this book and leave some comments about what you think about the future of the world.

Categories
Analog Electronics Economics Supply Chain

DC powered home

Either my readership has extended to people at multinational corporations or the idea is intrinsically viable enough to actually work! Either way, I’m happy.

Junko Yoshida of EE Times reports that Sharp Corp and TDK corp have both displayed home mock-ups that include DC modules running of of solar cells and do not require any AC/DC or DC/AC conversion (thereby saving power wasted on the conversion process). This is reminiscent of when I asked if DC can power an entire home. They cite instances of using DC power to directly use in LED home lighting, flatscreens and various other commercial products.

Looks like the idea is catching on, I can’t wait until it becomes possible for everyone!

Categories
Analog Electronics Digital Electronics Engineering Renewable Energy

Power Saving Techniques

Two things will make people want to use less power: not giving them much to start with and making it prohibitively expensive. Both of these scenarios seem to be dovetailing right now with the shrinking of many devices and energy becoming an ever more expensive and sought after.

Sure, there are people out there trying to create and harvest more energy. Either through more drilling, more wars, more acquisitions or new technologies. But eventually, people start to question why we are using so much energy in the first place. Instead of running device batteries into the ground quickly, why not draw less current? Instead of putting a bigger more expensive battery on a device in the first place, why not come up with new techniques to conserve power? Instead of paying high prices for energy and polluting the environment, why not conserve energy in our devices so that we don’t need as much energy overall?

Here are some of the methods that designers use in increasing numbers to reduce power consumption

  1. New chips — The basic idea is the same for any chip: Try and have the same or better performance of today’s chips with incrementally less power.  Most often, the best way to do so is to reduce the number of electrons it takes to store a value or drive another circuit (or whatever your task may be). However, there is a lower limit to how few electrons are required to complete a task (one, duh). How do we get less electrons doing these tasks?
    • Smaller geometries — Moore’s law tells us that process technologies will allow a doubling of technological ability every 18 months. This could even be a faster rate than previously thought, according to one of my favorite futurists, Ray Kurzweil. As fabrication facilities race to leapfrog one another to the next smallest process technology, they also help to reduce the number of electrons running through a device. If you look at the path of an electron along a trace on a microchip or op amp, it resembles a “tunnel” that electrons flow through. As process technologies get smaller and smaller (32 nm, anyone?) there is less room for electrons to flow through and thus, less power is used.
    • New materials — If you have less electrons flowing through a semiconductor, that means the total current flowing through the semiconductor is lower (current is defined as the number of electrons [measured in charge] flowing past a point for a period of time i.e. Coulombs per second). While less current can also mean less noise (fewer electrons bumping into other molecules and heating them up), it also means that if there is more resistance in a connection between two points, it will be harder for the electrons to travel that distance. As such, semiconductors are now made with new doping compounds (the molecules they force into silicon) or they forgo the silicon and try entirely new materials (Gallium Arsenide is a good example). These new materials allow for more efficient transistors and lower power consumption in devices.
    • New architectures — National Semiconductor has been pushing a new, more consistent power metric called “PowerWise“; it is targeted towards the mobile market and the “green revolution”. While this is a bit of a marketing move, it also helps to highlight their most efficient products across the different product types (LDOs vs Switching Regulators vs Op amps, etc).  Some of these newer, higher effeciency products use new architectures, as in the case of some of the switching regulators
    • Lower supply voltages — This one affects me on a more regular basis. Sure, the lower potential across a junction will drive less current in the off state (Iq) and will have less noise due to lower potentials; but this also throws a wrench in the works if you’re trying to find parts that will drive some significant currents or have any kind of large allowable input voltage ranges to a circuit without bootstrapping the supplies.
  2. PWM — Pulse Width Modulation (or PWM) is an easy way to reduce power in LED lighting situations. The idea is based off the fact that the human eye cannot determine the continuity of a light signal if it is below a certain frequency; instead, pulsing an LED on and off quickly will translate to the human eye as a lower intensity than an LED lit continuously. This idea is used regularly in portable electronics to dim the “backlight” of a laptop screen, cell phone, GPS device, etc. The duty cycle is the time that a device is powered divided by the total time it is on; usually it is given as a percentage. So if an LED is lit for 1 seconds and then off for 3 seconds (1 second on divided by 4 seconds total), the duty cycle is 25. In that example, the LED would appear to be one quarter as bright as a fully powered LED, but will also save a little less than 75% of the power normally required. The power saved can never be the entire difference between the normal case and the PWM case because some amount of power is required in order to switch between the on and off states.
  3. Microcontroller/Code Improvements — One of my favorite new blogs, written by Rick Zarr of National Semiconductor, has two great posts about the energy content of software. In it, he points out some of the ways that software can intelligently shut down portions of the code in order to reduce redundant processes and save on processing power. However, the points that I really like are the ones  he makes about making the simplest possible solution that will still get the job done well. This could mean cutting out some software libraries that were easier to just include in a project or learning how to properly construct a software project. Other techniques could be a combination of better coding and PWM: putting a device to “sleep” for a set period of time only to have it wake up at set intervals to see if it is needed.
  4. Going Analog — One last great point that Rick makes in his first post about energy saving techniques in software actually relates more to hardware. Instead of using a DSP, an ADC and some coded FIR filters, why not pull the filter back into the analog domain? Sure, it’s a little more difficult at the beginning but there won’t be any quantization errors (the error that comes from approximating a real signal with a digital signal). Analog engineers can do the same task with an active filter as digital engineers can do with a digital filter for many simpler applications. With the lower part count and the lower strain on the system of not converting a signal from analog to digital and back again, designers can save some significant power.

The final solution to our energy problems will be a combination of power saving techniques and new renewable energy sources. With some of the above techniques, designers will be able to use smaller batteries that allow longer usage times and have less of an impact on the environment. Please feel free to leave comments or any other power saving techniques you have heard of in the comments!

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Analog Electronics Learning

How an op amp works — Part 2

As promised, this post is a follow up post to explain the real-world behavior of an op amp. Here we will continue to anthropomorphize op amps in order to better understand their behavior and what they “want” to do. Also, we will look at some more complicated (but common) op amp configurations so that they are easily recognizable. Let’s begin.

First, let’s look at the symbol for the op amp:

Whoa-ho! What the heck are those? Last time, there was only 3 lines coming out of the triangle and now there’s five! They’re multiplying!

Really the “D” and “E” inputs are the power inputs to the op amp. This means we are no longer simply dealing with the “ideal” case and are now going to look at the behavior with some realistic expectations. I know that when I was first learning about op amps, I was perplexed by this idea. I thought, “Well what is the point of putting power into an op amp? What do I get for it?” The idea is that as long as the signal at the input (or more accurately the difference between “A” and “B” is smaller than the power at the “D” and “E” terminals, then the op amp can amplify the signal. This gets very useful once you start encountering signals that change over time, or AC signals (as opposed to DC signals). Let’s look at this idea below:


Special thanks to CoolMath.com for the graphing program!

On the top left, we see a SINE wave, which is one of the simplest time varying signals there is. Amplifying this signal would not shift the signal, but instead would make the entire range of the signal larger. If we used a 4x amplification, then we would get the top right picture with the larger signal. Notice in the bottom picture the overlay of these two signals. They do not SHIFT up, but instead look like they are stretched. The easiest way to think of all this is at the extremes. If in the first picture the highest point was 1 and we had 4x amplification, then the output would be 4. However, the middle point is 0 and that multiplied by 4 is still zero. Hence the reason the overlay shows the extreme highs and lows being “stretched” the most. Also, it is important to note that these are analog signals, so EVERY point in between the extremes is being amplified.

The power coming into the op amp also restricts how much the op amp can amplify a signal. Not only that, but sometimes you don’t even get to go to the limits! Say you have +15 volts attached to “D” and -15 volts attached to “E” (most op amps have lower voltages these days but +/- 15 volts still happens sometimes). Now let’s say you have a 1V signal coming into a non-inverting amplifier (shown below). The gain on this amplifier is set to 15 by making the top resistor 14 times less than the resistor connected to the ground (non-inverting amplifiers have a gain of 1+R(top)/R(gnd)). So our 1 volt signal is placed at the non-inverting input (the plus) and the op amp says “15 volts, coming right up!”. Ah, but the op amp doesn’t quite have it. The op amp outputs 13.4 volts are so and then stops. “But WAIT!” you say, “why can’t this op amp output as much as I wanted? The ideal ones can output INFINITY. Can’t I just get one of those?” The short answer: no, you can’t. Op amps have internal protection circuitry that limits how high the input to the op amp can be in order to protect it from blowing up. Additionally, the op amp must consume some of that power in order to actually amplify the input signal; this will be expounded upon in further posts (the internals of an opamp).

The final point in this continuing discussion about op amps, is known as slew rate. Really it is a discussion of how fast an op amp can go and is limited by capacitance. Inside of any op amp, there is a capacitor, or rather a bunch of components that act together as one capacitor. This creates a required charge time for the internals of the circuit (for a more advanced look at this topic, check out the allaboutcircuits.com article on capacitors and calculus). The end result is that the op amp has some limit to how fast it can “decide” what the output should be. If we think back to the signals above that alter with time, we can imagine a situation where they would vary so quickly that an op amp would not be able to keep up. The end result is that a circuit such as the non-inverting amplifier shown above has some frequency above which it can no longer accurately amplify. This is known as the bandwidth of the circuit and has implications in many audio, measurement and communication industries.

This post discussed some of the real world aspects of op amps. The next post will discuss the internals of the op amp, such as the transistor setups. Imperfections in the silicon and the realities of material science will show us that more of the “ideal” op amp model is not possible in every day life; some potential topics are the input bias currents, the voltage offsets across the input terminals and how they can affect everyday circuits.

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Categories
Analog Electronics Renewable Energy

Can DC power an entire home?

AC power vs. DC power: Both are necessary in our everyday lives and switching between the two causes a great deal of strife in electronics. Why do we need both?

As some of you may or may not know, there was a long standing battle between the two types of power raging back in the 1880s between two giants. The proponents of this war knew that whoever won would determine the future of the power distribution in the United States and possibly the world. In the first corner was Thomas Edison and his company that would eventually become General Electric; Edison wanted the world to run on DC. In the other corner was Westinghouse Corporation, funded by George Westinghouse and led (intellectually) by Nikola Tesla. Westinghouse represented AC power and would be the eventual winner. You can read more about the battle HERE, but I thought it would be interesting to point out that this battle eventually became a political one. Edison even started fighting dirty, secretly funding the invention and use of the first electric chair powered by AC, in order to give some bad press.

AC of course won out over DC as the power distribution of choice, mainly because of the ability to have large generators in a central location and then transmit the power efficiently over power lines to homes and businesses. DC would have required local generators on every street or even every home, which was not possible nor economically viable at the time.

Hang on a second though…a DC generator on every home…sounds familiar…where have I heard about something like this before? Oh right, solar power. However, even more interesting than the fact that solar power produces DC power output is that any kind of storage will have to be in DC. So THAT means if you have any kind of renewable energy resource on your premises (wind, geothermal, any kind of generator which will have an AC output) and it’s not continually supplying power to your home, you will likely need to store it somewhere (assuming you are not selling power back to the power company, which is the case in some areas still and a must in the remote areas). Further, barring any possibility of storing AC power (a huge inductor?), you will need to store that power in DC. So let’s look at a theoretical wind turbine on a theoretical property:

The wind blows –> wind turbine spins –> motor in turbine creates AC power –> AC converted to DC –> DC stored in a battery –> DC converted back to AC when needed –> AC powers devices in a home –> (possibly) AC converted back to DC for use in consumer devices

That’s a lot of steps! Not only are there a multitude of steps to convert wind into air conditioning (heh, the electrical way…the natural way is opening the window), there are lots of places that you will be losing energy to inefficiencies. These occur in the power generation (motors have friction), the storage in the batteries (heat and losses due to chemical impurities in the wet cells), the AC to DC conversion and the DC to AC conversion (both processes lose energy to heat in the electronics). All told, it’s not hard to see why this is not the preferred method of powering ones’ home.

So now the real question: Can we take out some of these steps?

Other articles on this site will deal with improving efficiencies of each of these steps, but the simplest method for improving overall efficiency would be to remove one or more of those steps. The way I see it, one of these ways would be to convert a power scheme in a house. Let’s look at all the ways a DC power system in a house could be beneficial or detrimental to ones’ living situation:

Concerns about DC wall power

  1. Many devices have different voltages
    • This would be a definite issue. Have you ever had to power a guitar pedal board? Random question perhaps, but if you saw what the power strip looks like, you’d catch my drift. Every one of those little electronic devices is too small for a transformer, so they all have AC-DC converters which can power the device with a different required voltage. Now take this idea and expand it to all the doo-dads in your house. I would be willing to guess that there are at LEAST 5 different required DC voltages for all of the normal devices in a home.
  2. Converting devices
    • Conversions would be required from DC->DC instead of AC->DC. A possible solution would be to set up the wall sockets to have selectable DC output (perhaps the home runs on 100V DC and each socket can convert this down to 24V, 12V, 5V, 3V).
  3. Selling power back to the power supply company
    • One of the most popular notions in renewable energy today is the idea of selling your excess power back to the power company, hopefully at a decent rate. Then when your device is not outputting power, you simply switch to grid power and start buying it from the power company. This is great because it does not require battery systems. And while this exercise excludes that option (for people living in the middle of nowhere or with unaccommodating power companies), it would be nice to sell any excess power back to make a small profit.
  4. Economies of Scale
    • This is possibly one of the biggest problems that an all DC power system would face: No one does it yet! All parts would have to be custom made and you couldn’t just call an electrician to come out and fix your stuff.
    • This also means that you would have a tough time buying consumer goods. Nearly every device has an AC plug, because that’s what everybody has! Not to mention all of the internal components for AC conversion and occasional power filtering (some devices need very clean DC power). Let’s just say you couldn’t go buy a TV and plug it in…
    • Government regulation would also limit any kind of large scale implementation of DC power sockets. It is almost guaranteed that it would require government certifications on many levels to allow manufacturing large enough quantities to bring the cost down for Mr. John Q Everyman.
  5. Conversion to AC for certain devices
    • Motors are the first kind that come to mind. This is basically how Nikola Tesla got started onto AC, proving that it is much more efficient when using AC than DC AND that these motors do not rely on voltage level (DC motors’ speed can be controlled by the voltage applied). This would mean you would either have to convert your DC back to AC to run the vacuum cleaner or you would have to make sure that your DC could supply constant DC and the whopping currents that those kinds of devices use.
  6. Step up/down transforming
    • You know those big garbage can looking things that are attached to power line poles? Those are changing the ridiculously high voltages in the power lines (done for transmission efficiency) down to something that we can use in our houses. Further, these are VERY high efficiency devices. For power in general, you really can’t beat AC-AC conversion; the system proposed here would have to use transistors (note: not transformers) which will have some amount of heat loss associated with them. So even though we wouldn’t be using the AC power from the power company, we would be losing a critical tool in the electrician/electrical engineers’ arsenal, the transformer.
  7. Leakage currents and phantom power consumption
    • No transistor is perfect, they all let just a little bit of current through. The more components in a system or the higher voltage you run at, the more leakage you will tend to have (Ever wonder why electronic devices run out of batteries eventually, even if you don’t use them for a long time?). This would apply to any DC system too and when you don’t have the lights on or anything running, there’s still a chance that the power devices are leaking. This will cut into overall efficiency.

Benefits of using DC instead of AC:

  1. Higher efficiencies off of battery power
    • This point was discussed above, but is THE main point of the article and for going to all this trouble. The less you need to convert between AC and DC, the less energy will go to waste. And if you do need an AC power source, the inverter could be much smaller, in order to handle smaller loads or in order to sell power back to the power company (once the battery is fully charged)
  2. LED Lighting
    • Currently any LED fixture installed in homes requires an AC-DC converter. Using a DC wiring system throughout a home would allow easy installation of LED fixtures and elements (the LEDs themselves)
  3. No 60 Hz hum
    • I’m sure most of you know what this sounds like from a faulty light switch, an older device with poor power supplies or even by sticking a fork in the wall. The native frequency of power coming out of the wall is 60Hz in the US, but varies by region. Either way, this is something that I’ve had to deal with at my job and that all electronics designs have to deal with. With an all DC system there would be other issues such as power filtering and voltage stability… no hum though!
  4. Shrinking power supplies
    • As devices continue to get smaller, the power supplies are reaching a lower limit. 1.8V is currently the lower end of DC supplies for microchips. This allows for less power consumption, as is governed by the formula P = V² * f * C (where P = power, V = voltage, F = frequency and C = capacitance). Have you ever noticed how they stopped increasing the frequency of microchips past a certain point (~3.5 GHz)? Yeah, it was because they started getting so hot you could fry eggs on the processors. Plus mobile processors became much more prevalent. As more and more devices go towards these lower voltages, there will be less need for conversion (or alternately, more need for AC-DC converters if wall power remains as AC).

So the final question comes back to that posed by the giants of the 19th century: AC or DC power? Well, really the answer will be both, as history has shown. Perhaps over time we’ll see a shift back towards DC power as devices continue to shrink and manufacturers don’t want to include bulky transformers or as people hopefully begin producing their own power at home; but one thing that is for certain is this battle will continue raging for a long time and hopefully we’ll help renewable energy find it’s place.

I welcome any and all comments on this idea and if you know of something being developed similarly, please let me know!

“If I have been able to see further than others, it is because I have stood on the shoulders of giants.” ~Sir Isaac Newton