ENERGY BASICS

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Energy Basics

Energy or Power?

Because energy is such a part of daily life, some of its basics tend to be overlooked.  For example, what is the difference between energy and power? The two terms are used interchangeably in conversation, but they have different meanings.  We’re all familiar with energy in a broad sense – in the sense of its physical meaning.  Power, however, refers to the rate of energy being used, generated, transferred, etc.  In other words, a kilowatt is a measure of energy, and a kilowatt-hour is a measure of power.

Measuring Energy

Kilowatts are only one way of measuring energy.  We also measure energy in terms of tons, cubic feet, gallons, and barrels.  The British Thermal Unit (commonly referred to simply as “Btu”) is a unit for comparing these different commonly used metrics.  The U.S. Energy Information Administration provides a useful list of common energy units expressed in terms of a Btu:

For more energy conversions, visit the EIA website, which offers several energy conversion calculators.

Distributed Energy

In contrast to large public utilities, “distributed energy” refers to smaller-scale power generators.  Typically, distributed power systems are more localized – serving individual residences, businesses, or other consumer groups.  Distributed energy has two main advantages: its flexibility and its reliability.  Distributed power can be generated from both renewable and non-renewable fuel sources (gas-fueled, hybrid, and renewable), which offers flexibility, and can serve as an alternative to more expensive power sources when need be.  Distributed power also offers an added level of reliability for businesses or other operations that require dependable and high-quality power.  The California Energy Commission provides an excellent overview of the definition and applications of different types of distributed generation.

Net Metering

For consumers who are connected to the grid and who also generate renewable energy, they may arrange a net metering agreement with the public utility.  If a net metering arrangement can be made, the consumer can draw electricity from the grid when needed, and can feed it back to the grid when the consumer has generated excess energy.  The public utility would then charge the consumer for their “net metering” – the energy they drew from the grid that was not made up for by energy they fed into it.   Net metering can be a highly beneficial arrangement, and provides for greater efficiency in electric use for all parties.  In Wyoming, all utilities are required to net meter renewable energy systems under 25 kW.

“On-the-Grid”

The vast majority of energy consumers are connected to the public grid.  Even those interested in generating renewable energy independently from the public electric utility provider may find it desirable to remain “on-the-grid.”  When connected to the public electric grid, power can be supplied during times when intermittent renewable resources are not available.  If you wish to generate renewable energy and remain connected to the grid, there are many requirements and regulations that you must become familiar with.  See our Codes and Requirements section below for more.

“Off-the-Grid”

For some consumers, choosing to be “off-the-grid” is a cost-effective and/or personal choice.  In very rural areas, the cost of extending power lines between the public electric grid and the residence can be high, making a stand-alone system more cost-effective.  However, a stand-alone system has several requirements.  Because renewable energies might be intermittent, a stand-alone system should have a reliable energy storage component and might combine electricity generation from multiple renewable resources.  A stand-alone system might include using geothermal or solar thermal technologies for indoor heating and cooling and water heating, in addition to electricity-generating technologies. 

Before choosing to live off-the-grid, consumers should carefully assess their renewable resources to make sure they can generate ample power, and ensure that they’ve met the regulatory and technical requirements of such a system.  If you are interested in making the transition off the grid, consult Extension before you get started.

Codes and Requirements

General

Whether you choose to be on the grid or off, investments in renewable energy will be subject to regulations on many levels.  Before investing in a stand-alone system or a grid-connected system, check with your local covenants, ordinances and building codes.  The U.S. Department of Energy offers a useful overview of the codes and requirements for small renewable energy systems, which consumers are encouraged to consult before moving forward with a renewable energy project.

Additionally, Wyoming residents should contact the Wyoming Public Service Commission and read carefully through the WPSC rules before undertaking a renewable energy project.

Grid-connected Systems

For obvious safety reasons, renewable energy systems that will be connected to the grid will need to meet several public utility requirements.  Technical requirements may include a means of disconnecting energy feed into the grid, power quality requirements, and automatic shut down capabilities, in addition to other power conditioning, safety, and metering equipment.  Additionally, the public utility will likely require the consumer to take out system liability insurance to protect the utility’s equipment.  Be sure to contact your local utility or the Wyoming Public Service Commission for this information.