Dear Control Engineering: I see there is new environmental legislation moving through congress involving a system called “cap and trade.” How is that supposed to work?

Cap and trade environmental regulation schemes are intended to provide polluting industries an opportunity to reduce emissions in a way that makes economic sense rather than simply imposing an arbitrary limit that hits everyone the same way.

Consider this scenario as an example: In your fictitious country you have 100 coal-burning power plants of roughly the same size. Let’s say the group breaks down as follows:

40 burn lo...Read More

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Dear Control Engineering:

When I hear the awful sound of a ball screw that’s beginning to fail on a CNC milling center, I have to wonder if there isn’t a better way to get that kind of linear movement. Are there other technologies?

We put that question to John Meyer at Siemens Motion Control Group, and he suggests linear motor technology:

Linear motors have not been part of the progression of modern machine design that has seen quantum leaps in control technology. Rather, modern machines still, for the most part, use slide propulsion that was designed in your grandfather’s day. We have gone from tape driven NC machines driven by dc servo motors and ball screws, to sophisticated CNC controls that can take a CAD file and produce a machine ...Read More

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Dear Control Engineering: With the price of gas headed up again, higher mileage cars are back in the news. What’s the story with a gasoline/pneumatic hybrid?

Hybrid cars are indeed back in the news. Chevrolet just suspended production of its hybrid Malibu because it didn’t deliver a high enough mileage gain to justify the additional cost. Adding the electric motor, batteries, and other equipment necessary for a hybrid isn’t cheap, so car builders are hunting for ways to get the benefits of hybrid technology with a lower sticker price. One technology under development is a pneumatic hybrid.

Basically the idea is that a piston engine is a lot like an air compressor, so a multi-cylinder engine can be configured such that s...Read More

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Dear Control Engineering: With reference to your discussion of in-ground CO₂ sequestration with FutureGen, my only concern with the "store the fizzy-water underground" concept is the incident that played-out in the Lake Nyos incident in Africa. The water released its stored CO₂ supply and flooded a village in the middle of the night when the lake erupted.

One technique for reducing the amount of atmospheric CO₂ (carbon dioxide) is to capture it at a source, typically a coal-fired power plant, and pump it into suitable rock formations and ...Read More

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Dear Control Engineering: Where is the price of oil headed? How much does the price of crude oil affect the price of gasoline?

You'd be hard pressed to find something more complicated than the global oil market given the huge number of factors influencing cost and the sheer scale of the industry. Macroeconomic pressures direct the price level globally, but most of us are more concerned with the pump price at the local gas station.

There is another entry in Pillar to Post that brings you more detail on where the industry is currently. Long story short, the oil industry in general has been experiencing a long period of underinvestment which will come back to haunt us all sooner or later.

There is an organizat...Read More

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Dear Control Engineering: You’ve been talking about advances in rechargeable batteries and capacitors. My i-Phone and laptop get all kinds of things wirelessly. How come I can’t receive power wirelessly? Is wireless power for wireless instrumentation in the works?

The most common way to transmit power without a direct electrical connection is through induction. It’s going on all around you in transformers, however those don’t cover a significant amount of distance.

Induction is being used to charge small devices like a Palm hand organizer or wireless handsets where the device is placed on a special pad or in a dock. The dock has a coil which serves effectively as the primary of the transformer. The device has a corresponding coi...Read More

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Dear Control Engineering: Your posting about developments in capacitor technology last week was interesting, but batteries have also made some major technical advances. Since the two technologies compete, how about some equal time?

Batteries have made many advances to move out of the carbon rod and zinc era. They fall into two major categories: disposable and rechargeable designs. (Technically, they’re known as primary and secondary batteries, respectively.) If you want to know about the former, check out Powering instrumentation: Batteries in the July 2008 issue of Control Engineering.

...Read More

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Dear Control Engineering: I've heard that capacitors can benefit from current research in nanotechnology. What are the hurdles keeping so-called "fuzzy capacitors" from being used today? Robert Paloutzian, Fresno, CA.

Let’s begin by explaining that a fuzzy capacitor is a super- or ultra-capacitor that uses carbon nanotubes to create surface area that stores the charge, sort of like all the individual threads of a fuzzy terrycloth towel increase its ability to soak up water. If this analogy doesn't make much sense to you, let’s put it in a larger context of capacitors and batteries as electrical storage devices.

If you remember your basic electrical training, you will r...Read More

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Dear Control Engineering:

I was reading a blog posting about using electric motors for cars and locomotives. I can understand how modern electronics can be used to control motors in those high torque applications like starting a train moving, but how was it done back in the pre-solid state times?

If you think back to the 1930s when Diesel-electric locomotives got serious, technology then was primarily "stone knives and bear skins," ...Read More

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Dear Control Engineering:

When I see articles about alternative generation technologies for electricity, they mention that a wind farm or solar park has an output of so-many kW or MW. What does this figure mean for technologies that don't operate all the time? Is it an average?

You're correct that neither solar nor wind generating technologies work all the time. Obviously sunlight is only available part of the day at best, and the wind isn't always blowing. My experience suggests that utility owners rate these projects at their maximum normal operating level, but they don't always produce at that level.

Wind turbines are placed in locations where average wind speed is sufficient to drive the turbine 60 to 80% of the time,...Read More

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Dear Control Engineering:

I was reading the story about the European biofuels group, making car and truck fuel from wood. What’s the chemical process that makes this possible, and is it practical in large volumes?

The process involved isn’t particularly new, but it has become more sophisticated over time. Basically, wood, coal or any biomass can be gasified by partial burning without enough oxygen for full combustion. The resulting synthetic gas stream contains primarily hydrogen (H₂) and carbon monoxide (CO). This product can be burned by itself, and often was in towns and cities serviced by a district gas supply plant. ...Read More

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Dear Control Engineering:

Most of the projects our company builds are used in North America, but we sometimes have to adapt equipment for overseas applications. Why is it that transformers capable of operating in a 50 Hz environment cost more than those for domestic 60 Hz operation? Is this a marketing ploy or is there a real justification for the cost difference?

We put this question to Steven Ensign at Ensign PowerVolt, a producer of transformers and power supplies. He answers:

In customer transformer specifications, it is frequently assumed that the transformer will operate at 60 Hz, and Ensign often must ask if the customer also requires 50 Hz operation. This is more than simply our version of, "Do you want fries with that?" The ability to operate at 50 H...Read More

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