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	Net energy gain - Wikipedia, the free encyclopedia
		Net Energy Gain is an important concept in energy economics, referring to the difference between the energy required to harvest the energy source against the energy provided by using that source.
		The term net energy gain can be used in slightly different ways: if the energy content of non-renewables is taken into account, they will always have a NEG below one; If only the extraction energy is counted, it can be higher.
		To calculate the NEG for society as a whole, in theory all externalities would have to be taken into account.
	en.wikipedia.org /wiki/Net_energy_gain (344 words)

	Energy balance (Site not responding. Last check: 2007-10-20)
		Theoretical basis for an energy balance is the first law of thermodynamics according to which energy cannot be created or destroyed, only modified in form.
		In energy economics, the energy balance of a country is an aggregate presentation of all human activities related to energy, except for natural and biological processes.
		Common methodology for compilation and presentation of energy balances allows simple addition of national energy balances to form supranational ones, such as is compiled for the European Union.
	www.1bx.com /en/Energy_balance.htm (238 words)

	Encyclopedia: Net energy gain
		Energy economics is a subfield of economics that focuses on energy relationships as the foundation of all other relationships.
		Energy balance has meanings in several fields: In physics, energy balance is a systematic presentation of energy flows and transformations in a system.
		EROEI (energy returned on energy invested) is the ratio between the amount of energy expended to obtain a resource, compared with the amount of energy obtained from that resource.
	www.nationmaster.com /encyclopedia/Net-energy-gain (607 words)

	Renewable Resources The Ethanol Forum
		The net energy gain is often expressed as a percent of the input energy.
		Using the latest energy data for agricultural requirements and ethanol plant use, several studies released in 2002 estimated that the net energy gain for corn ethanol is between 21 and 34 percent.
		The net energy is the sum of the energy content of ethanol and avoided energy related to co-products less the energy of all inputs.
	egov.oregon.gov /ENERGY/RENEW/Biomass/forum.shtml (4491 words)

	What's New at Prairie Swine Centre (Site not responding. Last check: 2007-10-20)
		Net energy, the efficiency of utilization of ME, is therefore defined as energy retained in the body or as the ME minus the energy lost as heat.
		Unlike the net energy used for maintenance (NEm) which is a non-productive use of energy, the producer is interested in the net energy used for gain, (NEg) which includes the energy required for growth - and the accompanying protein and lipid deposition - reproduction, lactation and work.
		Weight gain during gestation is required for growth of the reproductive tissues, storage of body reserves and possibly growth of the gilt or sow to mature size.
	www.prairieswine.ca /whatsnew/july2003/NetEnergy.htm (1163 words)

	Champion Feeders
		In growing finishing cattle, the maximum amount of energy that can be given to the cattle normally results in the maximum growth and the least units of feed per unit of cattle gain, as long as all other nutrient requirements are met.
		The energy content of feedstuffs using the net energy system is stated in terms of calories.
		Net energy calculations determine expected body gains, or are used to formulate rations for certain body gains.
	www.championfeeders.com /Newsletters_900389489/February01.htm (911 words)

	Energy consumption • Saskatchewan Eco Network (Site not responding. Last check: 2007-10-20)
		Energy consumption is dependent on the type of feedstock, the production process used, and the level of technology employed.
		If energy consumed in the production of ethanol is generated through the use of "dirty" fuels such as coal, the overall environmental impact is less positive.
		The net energy gain and environmental benefits of ethanol blended fuel are comprimised when "dirty" fuels are used to power any of the various stages of the production process.
	www.econet.sk.ca /issues/ethanol/energy.html (89 words)

	[No title]
		Gains can be estimated from past experience or by using net energy equations, which have been used for years to predict feedlot gain with a high degree of accuracy.
		When predicting gains with the program, the user is asked to calculate the Net energy for maintenance (NEm) and Net energy for gain (NEg) values of the diet on a dry matter basis.
		The net energy equations used are the steer and the heifer equations published in the 1976 and 1984 editions of the NRC Nutrient Requirements for Beef Cattle.
	www.ansi.okstate.edu /software/CR-304.DOC (1314 words)

	Body Condition Scoring II: Using the Net Energy (NE) System to Improve Body Condition Score
		The purpose of this guide is to help define the most commonly used system for expressing energy requirements for beef cows and energy concentration of feedstuffs, as well as using the system to improve cow body condition through evaluation of pasture or ration energy availability.
		A pound of gain on a thin cow is primarily made up of water and protein (muscle), whereas a pound of gain in a fat cow is mostly fat.
		For practical purposes, the efficiency of using energy for lactation and pregnancy is similar to using energy to meet maintenance requirements.
	www.ext.nodak.edu /extpubs/ansci/beef/as1198w.htm (1105 words)

	Nat' Academies Press, Nutrient Requirements of Dairy Cattle: Seventh Revised Edition, 2001 (2001)
		Energy and protein requirements for growth are estimated from the energy and protein content of the tissue deposited during growth (National Research Council, 19961.
		However, the equations used to compute the net energy and protein content of gain were not adjusted to account for the effect of mature weight.
		The maintenance requirement for energy was defined in Nutrient Requirements of Beef Cattle (National Research Council, 1996) as the intake of feed energy that results in no net loss or gain of energy from the tissues of the animal's body.
	www.nap.edu /books/0309069971/html/234.html (6326 words)

	Missouri Agricultural Experiment Station - Forage System Research Center
		Energy demand of yearling steers grazing these pastures was determined based on net energy requirements for maintenance and growth.
		Net energy available per acre was greatest throughout the season for the lowest stocking rate and least for the highest stocking rate ( Figure 3).
		Net energy available per acre varied through the season and was significantly affected by stocking rate.
	aes.missouri.edu /fsrc/research/rotate.stm (1503 words)

	Basic Information - Interpreting Lab Reports
		However, it is important to remember that the energy values presented are only estimates of the energy in the feedstuff calculated from Total Digestible Metabolizable energy (in kilocalories/lb).
		Net energy for maintenance (in megacalories/lb) is the portion of the metabolizable energy needed for the basal metabolism, that is, to keep the animal alive but not to grow, produce milk, etc. Net energy for maintenance must be met before any growth or other type of production can take place.
		Net energy/growth and net energy/lactation define the energy value of the feed to promote gain and lactation, respectively, when fed above maintenance.
	grasslands.clemson.edu /basic/lab.html (1389 words)

	CommonDefinitions (Site not responding. Last check: 2007-10-20)
		The energy of lipid (fat) is not used by microbes, so high fat diets will result in lower microbial protein per unit dietary energy and therefore will need to be supplemented with more UndegP.
		Energy is used less efficiently for growth than for meeting maintenance requirements.
		Generally the NEg value of grains is 60-70% of the NEm calue, and the NEg value of forages is 40-50% of the NEm calue.
	www.mmbiotech.com /commondefinitions.htm (1207 words)

	More or less energy? (Site not responding. Last check: 2007-10-20)
		More energy is contained in the ethanol and the other by-products of corn processing than is used to grow the corn and convert it into ethanol and by-products.
		Thus, the total energy output is 111,679 BTUs and the net energy gain is 30,589 BTUs for an energy output-input ratio of 1.38:1.
		In best-existing operations, assuming the corn is grown on the most energy efficient farms and the ethanol is produced in the most energy efficient plants, the net energy gain would be almost 58,000 BTUs for a net energy ratio of 2.09:1.
	www.alcohol4fuel.com /id18.html (2511 words)

	Karasov: Optimal digestion
		The shapes of the gain curves for the sugarbird and sunbirds are unknown.
		In the case of the decelerating gain curve, unless costs are extremely high the optimal amount of energy gained from the food is less than the total possible.
		However, in the case of the linear gain curve of hummingbirds digesting sucrose, the optimal amount of energy gained is near the maximum, so one predicts nearly complete digestion of sucrose meals.
	wildlife.wisc.edu /faculty/karasov/publications/s37.5.htm (5395 words)

	7. Factors affecting net energy accretion
		The energy unaccounted for, expressed as a percentage of the energy available for growth (293 kJ (70 kcal)/kg per day) would be: for fat 22%; for CHO 23%; and for pectin 61%.
		The energy is used by the intestinal microflora for growth, whereas most of the SCFA are absorbed through the colonic mucosa and may contribute to the host's energy supply.
		This represents approximately 75% of the original energy content of the carbohydrate; the remaining 25% may be used by the colonic microflora for growth.
	www.unu.edu /unupress/food2/UID09E/uid09e0r.htm (3967 words)

	The Energy Amplifier
		If the energy liberated becomes substantially greater than that needed to drive the accelerator, the process has a net gain and becomes self supporting.
		To illustrate the case for a beam energy of 7 Megawatts (7 mA protons produced by a state-of-the-art 1 GeV cyclotron) the EA would produce 280 MW of thermal energy, corresponding to about 100 MW of electrical power.
		The measured energy gain is of the order of 30, consistent with the simulation predictions.
	einstein.unh.edu /FWHersman/energy_amplifier.html (1196 words)

	Is ethanol energy-efficient?: Journey to Forever
		In this updated paper the numbers look even more attractive: more energy is contained in the ethanol and the other by-products of corn processing than is used to grow the corn and convert it into ethanol and by-products.
		David Pimentel's 1998 assessment of corn ethanol concluded that corn ethanol achieved a negative energy balance (which is usually defined as the energy in a product minus energy used to produce the product).
		This means that ethanol "yields 34% more energy than it takes to produce it, including growing the corn, harvesting it, transporting it and distilling it into ethanol." These data are consistent with a study by Dr. Bruce Dale, Michigan State University (2002), and a study by Argonne National Laboratory (1999).
	journeytoforever.org /ethanol_energy.html (2062 words)

	06.05.2003 - Producing ethanol from corn drains resources, says new report by UC Berkeley researchers
		The paper comes as the U.S. Senate debates a provision in the Energy bill that would double the amount of ethanol to be used as a gas additive to 5 billion gallons a year by 2012.
		Patzek and his students found that by the time ethanol is burned as a gasoline additive in our vehicles, the net energy lost is 65 percent, a figure that factors in the energy spent growing the corn and converting it into ethanol.
		In other words, the energy input of 4.93 gallons of gasoline equivalent leads to an energy output of 1.74 gallons of gasoline equivalent, or a net energy loss of 65 percent.
	www.berkeley.edu /news/media/releases/2003/06/05_ethanol.shtml (805 words)

	Estimating the Net Energy Balance of Corn Ethanol
		The net energy value (NEV) of corn ethanol was calculated as 16,193 Btu/gal when fertilizers are produced by modern processing plants, corn is converted in modern ethanol facilities, farmers achieve normal corn yields, and energy credits are allocated to coproducts.
		Energy used for planting the seed and other farm activities such as land preparation, plowing, weeding, distribution of fertilizer and chemicals, irrigating, harvesting, and drying, are included in the total farm fuels and electricity estimates.
		The energy used for blending along with the electricity used for dispensing the fuel from the pump is 672 Btu per gallon of ethanol.
	www.ethanol-gec.org /corn_eth.htm (7290 words)

	Solar Energy network
		In the face of deregulation and stringent environmental regulations, many utilities are looking for ways to gain customer loyalty and reduce pollution.
		Renewable energy sourcesalone will supply at least 80% of this with a combination of photovoltaics (PV), solar water heating, solar thermal electric, biomass, biogas and low impact hydro.
		With the electrical and natural gas energy distribution in a state utter chaos, great attention have been brought to alternative energy sources such as solar Parabolic concentrators and receiver tube applications which has been a proven technology for power generation for several years in California and manyother regions.
	www.solarenergy.net (766 words)

	WARMAIR.NET - Heat Gain
		The quantity of heat that needs to be removed to maintain indoor comfort, on a specific warm day for your region, is known as the heat gain for your structure*.
		It gains heat from the people inside of it, from the lights, computers, copiers, dishwashers and ovens.
		The sum of all of this heat accumulation is known as the heat gain of the building.
	www.warmair.net /html/heatgain.htm (514 words)

	Environment News Service ENS Latest Environmental Information Education Current Issues RSS
		The study concludes that the cumulative energy consumed in corn farming and ethanol production is six times greater than the power the ethanol provides in a car engine.
		The paper, published in the journal "Critical Reviews in Plant Science," comes as Congress debates a provision in the energy bill that would double the amount of ethanol to be used as a gasoline additive to five billion gallons a year by 2012.
		So, the energy input of 4.93 gallons of gasoline equivalent leads to an energy output of 1.74 gallons of gasoline equivalent, or a net energy loss of 65 percent.
	www.ens-newswire.com /ens/jul2005/2005-07-13-01.asp (1083 words)

	Planet Ark
		A BTU is the amount of energy needed to raise the temperature of a pound of water by one degree F. A gallon of gasoline contains 125,070 BTU.
		In calculating the "energy balance" of ethanol, researchers looked at energy use, including so-called farm inputs such as fuel, fertilizer and pesticides, energy used in converting grain into ethanol and fuel used for transportation, compared with the BTU value of ethanol and co-products from corn milling.
		If co-products were not considered, ethanol would have a net energy value of 1.08, the new study said.
	www.planetark.com /avantgo/dailynewsstory.cfm?newsid=17186 (702 words)

	Suomi Virtual Museum - Net Radiation (Site not responding. Last check: 2007-10-20)
		This absorption, and thus energy gain, by the atmosphere is primarily accomplished by water vapor, clouds, aerosols and ozone.
		Some of the surface-emitted energy escapes to space and the rest is absorbed by the atmosphere.
		This is not the case when the radiation gains and losses are averaged as a function of latitude.
	itg1.meteor.wisc.edu /wxwise/museum/a2/a2global.html (473 words)

	Considerations Regarding Net Energy Balance • Saskatchewan Eco Network
		The net energy gain (or loss) of ethanol production under various conditions is an important consideration that directly impacts the environmental benefits that can be achieved through the use of ethanol.
		Some argue that, if ethanol production consumes more energy than it produces, the result is an overall increase in fossil fuel consumption, with simply a shift in the polluting effects away from urban centres (where ethanol-blended is consumed) to rural areas, where fossil fuels are consumed to produce ethanol.
		Proponents of ethanol production say that if we can use a harmful fossil fuel at a net energy loss, we can certainly use a renewable source of liquid fuel that is less harmful to the environment and better for the domestic economy.
	www.econet.sk.ca /issues/ethanol/considerations.html (232 words)

	Introducing the "Net Gain" Concept
		However, concern generated by the California energy crisis and the earlier "Y2K" issue have begun to change peoples' awareness.
		Whether concerns of flouts, a natural disaster, or a future restriction of the availability of oil and natural gas, many people are considering independence from the grid by turning their homes into energy producers.
		They are creating homes which show a "net gain" of energy, not a net loss.
	solarquest.net /products/brochure/brochure2 (783 words)

	WestStart-CALSTART
		Critics have suggested that the renewable fuel had a net energy loss, based on the entire production process.
		The U.S. Department of Energy's Office (DOE) of Energy Efficiency and Renewable Energy said the Argonne study, conducted by Michael Wang, should help quell debate about the net energy balance of ethanol.
		In the last 10 years, only two studies - both conducted by Cornell University entomologist David Pimentel - have found the net energy balance of ethanol to be negative.
	www.calstart.org /info/newsnotes/nn_detail.php?id=7306 (291 words)

	TOPIC 2. OPTIMALITY MODELS
		THE NET RATE OF ENERGY GAIN AFTER TIME t IS; [f(t)-C(T+t)]/T+t WHICH SIMPLIFIES TO [f(t)/(T+t)] - C. WOULD MAXIMIZE THIS FUNCTION WRT t.
		IN THIS CASE THE NET RATE OF ENERGY GAIN WOULD BE [f(t) - g(t,T,f(t))]/(T+t) WHICH DOES NOT SIMPLIFY (DIFFERENT DERIVATIVE) AND WOULD PREDICT A DIFFERENT OPTIMAL BEHAVIOUR.
		THEREFORE WHEN THE BEES DID NOT APPEAR TO BE MAXIMIZING THE RATE OF GAIN OF NECTAR (GROSS ENERGY) THIS DOES NOT MEAN THAT THEY WERE NOT MAXIMIZING THE NET RATE OF ENERGY GAIN, THIS WAS NOT TESTED AS THE COSTS WERE NOT QUANTIFIED.
	www.ucs.mun.ca /~dunbrack/4701optimality.html (889 words)

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