Be a player when it comes to electrical energy efficiency

Industrial Energy Management: The U.S. electrical grid is characterized by mechanical switches with slow response times, a lack of analytics, and poor system visibility. Sounds like a job for an automation engineer.

01/17/2012


Electricity can be compared to a tomato – it doesn’t travel well or store easily. Just like the tomato, it must be consumed soon after and close to where it’s produced.

The electrical power grid comprises all utilities, networks, and systems used to generate power and deliver it to consumers. Generation plants produce on demand; the electricity radiates out through a series of substations and progressively lower-voltage transmission lines until it reaches its use point. In fact, except for very small amounts stored in batteries or capacitors, electricity is consumed as it is produced.

In a hydroelectric power plant, for example, demand coming from energy users draws power from the turbine. The greater the demand, the harder the turbine is to turn and the more energy transfers from the water into electrical power. When demand slackens, the turbine turns more easily; the water’s excess energy continues down river.

In the U.S., peak demand almost invariably occurs between late morning and evening on summer days. Since generating facilities must meet demand at any given moment, some generation plants sit idle until needed. Maintaining these “peaker” plants is expensive and inefficient.

Currently, utility pricing varies by region. In some places, like California, tiered pricing structures and usage- curtailment programs discourage consumption during peak loads. In other places, costs are lower and utilities still charge flat rates, with less incentive for demand reduction.

Reaching its limits

Hailed by the National Academy of Engineering as the most important engineering achievement of the 20th century, the U.S. electrical power grid serves with remarkable reliability. But, despite computer, telecommunications, and automation advances, and while both total power demand and intolerance of power fluctuations have increased, the system hasn’t evolved.

“Our nation’s electric power infrastructure that has served us so well for so long—also known as ’the grid’—is rapidly running up against its limitations…the largest interconnected machine on Earth…It consists of more than 9,200 electric generating units with more than 1,000,000 MW of generating capacity connected to more than 300,000 miles of transmission lines,” notes a U.S. Department of Energy publication, The Smart Grid: An Introduction.

Transmission and delivery are fairly well automated within individual substations. Data sharing among utility companies is increasing. But coordination at a higher level is in its infancy. Interoperability among grid stakeholders is immature. The current grid needs a major overhaul, the same Department of Energy publication notes: “More blackouts and brownouts are occurring due to the slow response times of mechanical switches, a lack of automated analytics, and ‘poor visibility’—a lack of situational awareness on the part of operators.”

What’s a Smart Grid?

The Smart-Grid vision is for a reworked infrastructure:

  • Prices reflect what it costs to produce electricity at that time.
  • All methods of generation and storage are incorporated.
  • The system is secure, efficient, and environmentally sound.

Because a Smart Grid allows supply-demand response, electricity is managed real time, at increasing levels of automation. Utilities know how much and where electricity is produced and where it’s used. They can anticipate potential problems and shift supply to high-demand areas. This reduces brownouts and blackouts and leads to better quality electrical energy.

But this vision of two-way communication and automated energy management demands open standards. Data from many sources must be aggregated, integrated, and presented visually in varied formats. The standard expected to ensure Smart Grid interoperability is IEC 61850. Developed by the International Electrotechnical Commission and originally meant for substation automation, IEC 61850 denotes use of standard Ethernet communications.

Pricing is determined by real-time production, transmission, and distribution costs. With tiered or actual-cost pricing, users have incentives to adjust consumption to avoid peaks. More predictable demand and automation use save capital and operating costs. The Smart Grid accepts energy from distributed, variable-output sources and accommodates new storage methods as well. If a plant has a photovoltaic system on its roof, the grid may be able to rely on it for electricity during high demand periods. The Smart Grid envisions a future with reliable, secure power that’s automatically adjusted for the greatest efficiency. But major automation projects take a long time, and this will be one of the largest automation projects ever undertaken.

Playing with the Smart Grid

There’s no need to wait for the Smart Grid, smart machines, or further technology innovation. Working with your utility or power broker, become a player in the Smart Grid right now, using these three steps:

  1. Get detailed data on your company’s energy usage.
  2. Control energy usage and costs.
  3. Gain a revenue stream through utility company rebates, credits, and curtailment programs.

You may already be monitoring things such as refrigeration units. Use or expand this data. Add I/O to the current automation system to measure energy use or put in a separate control system for that purpose. In either case, Ethernet networking and open standards simplify energydata reporting. Look for vendors offering Ethernet-based programmable automation controllers, switches, wireless radios, and other open-standard components.

Initially you may choose to monitor usage as an aggregate, e.g., for a building or process. Note usage change when certain motors, compressors, or even lights come on. In some cases, wiring direct to a pump, motor, or other heavy energy user may be more direct. Maintenance will be interested to know when a motor starts drawing extra current.

Once you analyze the data, the next step is to control use. Choose a system that can control as well as monitor.

Detailed usage data can be analyzed for patterns:

  • Which equipment or processes require the most energy and which the least?
  • What is the daily energy usage pattern? What is the seasonal pattern?
  • Look for quick benefits:
  • Replace an energy-hogging motor with one having a variable-frequency drive.
  • Run processes sequentially rather than concurrently to reduce the electrical load at certain times of day.
  • Change the temperature slightly to make a big difference in compressor run time.

Control energy use and costs

The next step is to tie usage to costs and control both. Pricing structures vary. However, the trend is toward dynamic pricing based upon total usage during a billing period or even time-of-use per day. TOU billing is a move toward real-time pricing and already available in much of California.

When paying a flat rate, the only way to save is by reducing overall usage. But if pricing is dynamic, opportunities are greater. Tie the energy data from machinery, processes, and buildings to the electric rates, and see what savings are possible. For example, schedule a highenergy- use process for early in the day. Or shed loads when overall usage approaches a higher-priced tier.

You are now ready to better manage process energy use. Based on the usage-data analysis, start with one or two areas where the impact will be greatest; then move on from there. Large corporations may hire consultant services. For small- and medium-sized industrial companies, however, their own engineers and technicians know the facilities and processes intimately and are usually the best choice to make energy decisions.

Utility companies can also help. Many offer free energy audits or testing programs to identify problems and suggest solutions. Testing may include power-factor studies, locating transient voltage problems, and detailing load profiles. Cash rebate and curtailment programs not only save money but can even provide a revenue stream.

Gain a revenue stream

To gain a revenue stream you need to look at energy in a different way. Consider it another raw material required to make a product. That cost is then an item on the product bill of material, reflected in the price charged for the product and production decisions.

Many utility companies and power brokers offer cash rebates and curtailment programs. Cash-rebate programs pay for replacing inefficient equipment with variable frequency drives or more efficient motors, chillers, and lighting devices.

Financial assistance may be available for installing self-generation systems, such as solar photovoltaic and wind power, or equipment to permanently shift loads. For example, make ice or chill water during summer nights. Check the return on investment before investing, keeping rebates and financial assistance in mind.

Curtailment programs pay companies each month in return for reduced energy use, either automatically or upon request. Curtailment programs deliver an effective revenue stream and may be offered by private aggregator firms. Dynamic-demand programs involve devices attached to, for example, a compressor or air conditioner. These devices, usually provided by the utility company at little or no cost, sense stress in the grid and respond by temporarily shutting off power to that equipment.

Demand-response programs are not usually automatic. Instead, the utility provider calls to request load shedding. A response within a specified period of time—say 30 minutes—must then reduce energy use to a predetermined level. Realize that if the response isn’t within the time required or to the level agreed upon, there’s a penalty. With a smart meter, request and response can be automated.

www.opto22.com

www.iec.ch/smartgrid

Sinha has more than 20 years’ experience in instrumentation, controls, and automation. He started his career as an engineer in the power industry, then transitioned to the business side of the technology, holding marketing and sales positions with Emerson Process Management and Schneider Electric. Sinha joined Opto 22 in 2006 and is currently director of business development. He has a BS in mechanical engineering from the University of California, San Diego, and an MBA from Webster University. Femia has written about technical products and trends for more than 20 years. She is currently information architect at Opto 22, where she focuses on industrial control and energy management.

This is part of the Control Engineering December 2012 Industrial Energy Management supplement.


Manage energy smarter today: 5 tips

The national automation project known as the Smart Grid will take decades to complete. But your company’s interest in energy management can begin now.

Here are some easy ways to start:

 

  • Think about energy as a raw material and even a revenue source.
  • Use automation technology and products available now to acquire data. Analyze energy usage in as granular a form as needed.
  • Use readily available products based on open communication standards to send this data to company computer networks, online software services, and operator interfaces.
  • Based on the data acquired, set up automated or operator-driven control for devices and processes to use energy efficiently.
  • Take advantage of rebate and curtailment programs offered by energy providers to acquire new equipment or even produce a new revenue stream.

- Arun Sinha and Jean W. Femia are with Opto 22.

www.opto22.com

 



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