Reply #103: You should enhance your understanding of "energy carriers" [View All]

[kristopher]

A. What is an Energy Carrier?
An energy carrier is a means of transforming energy from a less useful form, location, or intensity into a more useful state. It is more of an economic than a thermo-dynamic concept. Historically, people were the first purposeful energy carriers. They consumed plants and animals' low-intensity carbohydrate energy; and transformed this food into useful and highly controllable work in locations at some distance from the food source. Humans soon co-opted other humans, then draft animals, shaft power, coal gas, fossil distillates, and electricity for use as energy carriers. These carriers allowed a variety of primary energy sources such as solar energy captured via plants, the potential energy of water flowing downhill, and the thermo-chemical energy of fossil fuels to become useful for tilling crops, building homes, fighting wars, providing pinpoint mechanical power, lighting buildings, and performing computations. Hydrogen and liquid biofuels are now being considered as potential additional energy carriers.

B. Characterizing Energy Carriers
Some desired characteristics of energy carriers are deducible from first principles, while others spring from analogy and reflection.

The first law of thermodynamics tells us that energy can be moved around but cannot be created or destroyed except via nuclear processes. Characterizations of energy carriers depend in part on this conservation law, which allows us to say how efficient carriers are in terms of energy in versus energy out. Yet, the first law also reminds us that energy carriers are always embedded in a longer production chain, so that we should not forget what comes before and after the carrier. The extraction and transportation processes of the coal fuel and the end use performance of the light bulb are both relevant when evaluating electricity as an energy carrier <1>.

The second law of thermodynamics tells us that energetic order tends toward disorder. Much of engineering practice and, arguably, of human civilization and of life itself are efforts to fight increasing entropy. Energy carriers play a crucial role in this drama by helping to transform inconveniently located and low-quality energy into high-quality energy located where and when we want it. Yet, there is an associated cost in mine tailings, waste heat, and other inevitable dissipative losses. Such waste is "virtuous" to the extent that it allows local increases in energetic order <2>, although a proper calculation of virtue would weigh the net of these dispersed costs and concentrated benefits as they impact society. Thus, the second law forces consideration of both the positive and negative impacts associated with energy carriers, as well as the spatial and social scope of those impacts.

By analogy, a good energy carrier is like money, it... (pg 1853)


Andrews: and Implementing Public Policy for New Energy Carriers
Vol. 94, No. 10, October 2006 | Proceedings of the IEEE

http://policy.rutgers.edu/faculty/andrews/031IEEE.pdf


And if you'd like to review something a bit more detailed that looks at a specific path of energy though a subset of our infrastructure. Similar analysis exist for all areas. They ask for people not to post the content of the paper, but they do make it available for download.

Optimal Power Flow of Multiple Energy Carriers Martin Geidl, Student Member, IEEE, and Goran Andersson, Fellow, IEEE
IEEE TRANSACTIONS ON POWER SYSTEMS, VOL. 22, NO. 1, FEBRUARY 2007 145
http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.164.5417&rep=rep1&type=pdf