Waste heat

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Thermal oxidizers can use a regenerative process for waste heat from industrial systems. Regenerative thermal oxidizer.jpg
Thermal oxidizers can use a regenerative process for waste heat from industrial systems.
Air conditioning units extract heat from a dwelling interior with coolant, and transfer it to the dwelling exterior as waste. They emit additional heat in their use of electricity to power the devices that pass heat to and from the coolant. 2008-07-11 Air conditioners at UNC-CH.jpg
Air conditioning units extract heat from a dwelling interior with coolant, and transfer it to the dwelling exterior as waste. They emit additional heat in their use of electricity to power the devices that pass heat to and from the coolant.

Waste heat is heat that is produced by a machine, or other process that uses energy, as a byproduct of doing work. All such processes give off some waste heat as a fundamental result of the laws of thermodynamics. Waste heat has lower utility (or in thermodynamics lexicon a lower exergy or higher entropy) than the original energy source. Sources of waste heat include all manner of human activities, natural systems, and all organisms, for example, incandescent light bulbs get hot, a refrigerator warms the room air, a building gets hot during peak hours, an internal combustion engine generates high-temperature exhaust gases, and electronic components get warm when in operation.

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Instead of being "wasted" by release into the ambient environment, sometimes waste heat (or cold) can be used by another process (such as using hot engine coolant to heat a vehicle), or a portion of heat that would otherwise be wasted can be reused in the same process if make-up heat is added to the system (as with heat recovery ventilation in a building).

Thermal energy storage, which includes technologies both for short- and long-term retention of heat or cold, can create or improve the utility of waste heat (or cold). One example is waste heat from air conditioning machinery stored in a buffer tank to aid in night time heating. Another is seasonal thermal energy storage (STES) at a foundry in Sweden. The heat is stored in the bedrock surrounding a cluster of heat exchanger equipped boreholes, and is used for space heating in an adjacent factory as needed, even months later. [1] An example of using STES to use natural waste heat is the Drake Landing Solar Community in Alberta, Canada, which, by using a cluster of boreholes in bedrock for interseasonal heat storage, obtains 97 percent of its year-round heat from solar thermal collectors on the garage roofs. [2] [3] Another STES application is storing winter cold underground, for summer air conditioning. [4]

On a biological scale, all organisms reject waste heat as part of their metabolic processes, and will die if the ambient temperature is too high to allow this.

Anthropogenic waste heat can contribute to the urban heat island effect. [5] The biggest point sources of waste heat originate from machines (such as electrical generators or industrial processes, such as steel or glass production) and heat loss through building envelopes. The burning of transport fuels is a major contribution to waste heat.

Conversion of energy

Machines converting energy contained in fuels to mechanical work or electric energy produce heat as a by-product.

Sources

In the majority of applications, energy is required in multiple forms. These energy forms typically include some combination of heating, ventilation, and air conditioning, mechanical energy and electric power. Often, these additional forms of energy are produced by a heat engine running on a source of high-temperature heat. A heat engine can never have perfect efficiency, according to the second law of thermodynamics, therefore a heat engine will always produce a surplus of low-temperature heat. This is commonly referred to as waste heat or "secondary heat", or "low-grade heat". This heat is useful for the majority of heating applications, however, it is sometimes not practical to transport heat energy over long distances, unlike electricity or fuel energy. The largest proportions of total waste heat are from power stations and vehicle engines.[ citation needed ] The largest single sources are power stations and industrial plants such as oil refineries and steelmaking plants.[ citation needed ]

Air conditioning

Conventional air conditioning systems are a source of waste heat by releasing waste heat into the outdoor ambient air whilst cooling indoor spaces. This expelling of waste heat from air conditioning can worsen the urban heat island effect. [5] Waste heat from air conditioning can be reduced through the use of passive cooling building design and zero-energy methods like evaporative cooling and passive daytime radiative cooling, the latter of which sends waste heat directly to outer space through the infrared window. [6] [7]

Power generation

The electrical efficiency of thermal power plants is defined as the ratio between the input and output energy. It is typically only 33% when disregarding usefulness of the heat output for building heat. [8] The images show cooling towers, which allow power stations to maintain the low side of the temperature difference essential for conversion of heat differences to other forms of energy. Discarded or "waste" heat that is lost to the environment may instead be used to advantage.

A coal-fired power station. These transform chemical energy into 36-48% electricity and the remaining 52-64% to waste heat. Coal power plant Datteln 2 Crop1.png
A coal-fired power station. These transform chemical energy into 36–48% electricity and the remaining 52–64% to waste heat.

Industrial processes

Industrial processes, such as oil refining, steel making or glass making are major sources of waste heat. [9]

Electronics

Although small in terms of power, the disposal of waste heat from microchips and other electronic components, represents a significant engineering challenge. This necessitates the use of fans, heatsinks, etc. to dispose of the heat.

For example, data centers use electronic components that consume electricity for computing, storage and networking. The French CNRS explains a data center is like a resistor and most of the energy it consumes is transformed into heat and requires cooling systems. [10]

Biological

Humans, like all animals, produce heat as a result of metabolism. In warm conditions, this heat exceeds a level required for homeostasis in warm-blooded animals, and is disposed of by various thermoregulation methods such as sweating and panting. [11]

Cooling towers evaporating water at Ratcliffe-on-Soar Power Station, United Kingdom RatcliffePowerPlantBlackAndWhite.jpg
Cooling towers evaporating water at Ratcliffe-on-Soar Power Station, United Kingdom

Disposal

Low temperature heat contains very little capacity to do work (Exergy), so the heat is qualified as waste heat and rejected to the environment. Economically most convenient is the rejection of such heat to water from a sea, lake or river. If sufficient cooling water is not available, the plant can be equipped with a cooling tower or air cooler to reject the waste heat into the atmosphere. In some cases it is possible to use waste heat, for instance in district heating systems.

Uses

Conversion to electricity

There are many different approaches to transfer thermal energy to electricity, and the technologies to do so have existed for several decades.

An established approach is by using a thermoelectric device, [12] where a change in temperature across a semiconductor material creates a voltage through a phenomenon known as the Seebeck effect.

A related approach is the use of thermogalvanic cells, where a temperature difference gives rise to an electric current in an electrochemical cell. [13]

The organic Rankine cycle, offered by companies such as Ormat, is a very known approach, whereby an organic substance is used as working medium instead of water. The benefit is that this process can reject heat at lower temperatures for the production of electricity than the regular water steam cycle. [14] An example of use of the steam Rankine cycle is the Cyclone Waste Heat Engine.

Cogeneration and trigeneration

Waste of the by-product heat is reduced if a cogeneration system is used, also known as a Combined Heat and Power (CHP) system. Limitations to the use of by-product heat arise primarily from the engineering cost/efficiency challenges in effectively exploiting small temperature differences to generate other forms of energy. Applications utilizing waste heat include swimming pool heating and paper mills. In some cases, cooling can also be produced by the use of absorption refrigerators for example, in this case it is called trigeneration or CCHP (combined cooling, heat and power).

District heating

Waste heat can be used in district heating. Depending on the temperature of the waste heat and the district heating system, a heat pump must be used to reach sufficient temperatures. These are an easy and cheap way to use waste heat in cold district heating systems, as these are operated at ambient temperatures and therefore even low-grade waste heat can be used without needing a heat pump at the producer side. [15]

Pre-heating

Waste heat can be forced to heat incoming fluids and objects before being highly heated. For instance, outgoing water can give its waste heat to incoming water in a heat exchanger before heating in homes or power plants.

Anthropogenic heat

Anthropogenic heat is heat generated by humans and human activity. The American Meteorological Society defines it as "Heat released to the atmosphere as a result of human activities, often involving combustion of fuels. Sources include industrial plants, space heating and cooling, human metabolism, and vehicle exhausts. In cities this source typically contributes 15–50 W/m2 to the local heat balance, and several hundred W/m2 in the center of large cities in cold climates and industrial areas." [16] In 2020, the overall anthropogenic annual energy release was 168,000 terawatt-hours; given the 5.1×1014 m2 surface area of Earth, this amounts to a global average anthropogenic heat release rate of 0.04 W/m2. [17] [18]

Environmental impact

Anthropogenic heat is a small influence on rural temperatures, and becomes more significant in dense urban areas. [19] It is one contributor to urban heat islands. Other human-caused effects (such as changes to albedo, or loss of evaporative cooling) that might contribute to urban heat islands are not considered to be anthropogenic heat by this definition.

Anthropogenic heat is a much smaller contributor to global warming than greenhouse gases are. [20] In 2005, anthropogenic waste heat flux globally accounted for only 1% of the energy flux created by anthropogenic greenhouse gases. The heat flux is not evenly distributed, with some regions higher than others, and significantly higher in certain urban areas. For example, global forcing from waste heat in 2005 was 0.028 W/m2, but was +0.39 and +0.68 W/m2 for the continental United States and western Europe, respectively. [21]

Although waste heat has been shown to have influence on regional climates, [22] climate forcing from waste heat is not normally calculated in state-of-the-art global climate simulations. Equilibrium climate experiments show statistically significant continental-scale surface warming (0.4–0.9 °C) produced by one 2100 AHF scenario, but not by current or 2040 estimates. [21] Simple global-scale estimates with different growth rates of anthropogenic heat [23] that have been actualized recently [24] show noticeable contributions to global warming, in the following centuries. For example, a 2% p.a. growth rate of waste heat resulted in a 3 degree increase as a lower limit for the year 2300. Meanwhile, this has been confirmed by more refined model calculations. [25]

A 2008 scientific paper showed that if anthropogenic heat emissions continue to rise at the current rate, they will become a source of warming as strong as GHG emissions in the 21st century. [26]

See also

Related Research Articles

<span class="mw-page-title-main">Urban heat island</span> Situation where cities are warmer than surrounding areas

Urban areas usually experience the urban heat island (UHI) effect, that is, they are significantly warmer than surrounding rural areas. The temperature difference is usually larger at night than during the day, and is most apparent when winds are weak, under block conditions, noticeably during the summer and winter. The main cause of the UHI effect is from the modification of land surfaces while waste heat generated by energy usage is a secondary contributor. Urban areas occupy about 0.5% of the Earth's land surface but host more than half of the world's population. As a population center grows, it tends to expand its area and increase its average temperature. The term heat island is also used; the term can be used to refer to any area that is relatively hotter than the surrounding, but generally refers to human-disturbed areas.

<span class="mw-page-title-main">Passive solar building design</span> Architectural engineering that uses the Suns heat without electric or mechanical systems

In passive solar building design, windows, walls, and floors are made to collect, store, reflect, and distribute solar energy, in the form of heat in the winter and reject solar heat in the summer. This is called passive solar design because, unlike active solar heating systems, it does not involve the use of mechanical and electrical devices.

In the study of heat transfer, radiative cooling is the process by which a body loses heat by thermal radiation. As Planck's law describes, every physical body spontaneously and continuously emits electromagnetic radiation.

<span class="mw-page-title-main">Heat transfer</span> Transport of thermal energy in physical systems

Heat transfer is a discipline of thermal engineering that concerns the generation, use, conversion, and exchange of thermal energy (heat) between physical systems. Heat transfer is classified into various mechanisms, such as thermal conduction, thermal convection, thermal radiation, and transfer of energy by phase changes. Engineers also consider the transfer of mass of differing chemical species, either cold or hot, to achieve heat transfer. While these mechanisms have distinct characteristics, they often occur simultaneously in the same system.

<span class="mw-page-title-main">Thermoelectric cooling</span> Electrically powered heat-transfer

Thermoelectric cooling uses the Peltier effect to create a heat flux at the junction of two different types of materials. A Peltier cooler, heater, or thermoelectric heat pump is a solid-state active heat pump which transfers heat from one side of the device to the other, with consumption of electrical energy, depending on the direction of the current. Such an instrument is also called a Peltier device, Peltier heat pump, solid state refrigerator, or thermoelectric cooler (TEC) and occasionally a thermoelectric battery. It can be used either for heating or for cooling, although in practice the main application is cooling. It can also be used as a temperature controller that either heats or cools.

Active cooling is a heat-reducing mechanism that is typically implemented in electronic devices and indoor buildings to ensure proper heat transfer and circulation from within.

<span class="mw-page-title-main">Heat recovery ventilation</span> Method of reusing thermal energy in a building

Heat recovery ventilation (HRV), also known as mechanical ventilation heat recovery (MVHR) or energy recovery ventilation (ERV), is a ventilation system that recovers energy by operating between two air sources at different temperatures. It is used to reduce the heating and cooling demands of buildings.

The climate in urban areas differs from that in neighboring rural areas, as a result of urban development. Urbanization greatly changes the form of the landscape, and also produces changes in an area's air. The study of urban climate is urban climatology.

<span class="mw-page-title-main">Thermal energy storage</span> Technologies to store thermal energy

Thermal energy storage (TES) is the storage of thermal energy for later reuse. Employing widely different technologies, it allows surplus thermal energy to be stored for hours, days, or months. Scale both of storage and use vary from small to large – from individual processes to district, town, or region. Usage examples are the balancing of energy demand between daytime and nighttime, storing summer heat for winter heating, or winter cold for summer cooling. Storage media include water or ice-slush tanks, masses of native earth or bedrock accessed with heat exchangers by means of boreholes, deep aquifers contained between impermeable strata; shallow, lined pits filled with gravel and water and insulated at the top, as well as eutectic solutions and phase-change materials.

<span class="mw-page-title-main">Sustainable architecture</span> Architecture designed to minimize environmental impact

Sustainable architecture is architecture that seeks to minimize the negative environmental impact of buildings through improved efficiency and moderation in the use of materials, energy, development space and the ecosystem at large. Sustainable architecture uses a conscious approach to energy and ecological conservation in the design of the built environment.

Renewable heat is an application of renewable energy referring to the generation of heat from renewable sources; for example, feeding radiators with water warmed by focused solar radiation rather than by a fossil fuel boiler. Renewable heat technologies include renewable biofuels, solar heating, geothermal heating, heat pumps and heat exchangers. Insulation is almost always an important factor in how renewable heating is implemented.

<span class="mw-page-title-main">Ground-coupled heat exchanger</span> Underground heat exchanger loop that can capture or dissipate heat to or from the ground

A ground-coupled heat exchanger is an underground heat exchanger that can capture heat from and/or dissipate heat to the ground. They use the Earth's near constant subterranean temperature to warm or cool air or other fluids for residential, agricultural or industrial uses. If building air is blown through the heat exchanger for heat recovery ventilation, they are called earth tubes.

Seasonal thermal energy storage (STES), also known as inter-seasonal thermal energy storage, is the storage of heat or cold for periods of up to several months. The thermal energy can be collected whenever it is available and be used whenever needed, such as in the opposing season. For example, heat from solar collectors or waste heat from air conditioning equipment can be gathered in hot months for space heating use when needed, including during winter months. Waste heat from industrial process can similarly be stored and be used much later or the natural cold of winter air can be stored for summertime air conditioning.

<span class="mw-page-title-main">Energy recovery</span>

Energy recovery includes any technique or method of minimizing the input of energy to an overall system by the exchange of energy from one sub-system of the overall system with another. The energy can be in any form in either subsystem, but most energy recovery systems exchange thermal energy in either sensible or latent form.

<span class="mw-page-title-main">Passive cooling</span> Building design approach

Passive cooling is a building design approach that focuses on heat gain control and heat dissipation in a building in order to improve the indoor thermal comfort with low or no energy consumption. This approach works either by preventing heat from entering the interior or by removing heat from the building.

<span class="mw-page-title-main">Thermoelectric generator</span> Device that converts heat flux into electrical energy

A thermoelectric generator (TEG), also called a Seebeck generator, is a solid state device that converts heat directly into electrical energy through a phenomenon called the Seebeck effect. Thermoelectric generators function like heat engines, but are less bulky and have no moving parts. However, TEGs are typically more expensive and less efficient. When the same principle is used in reverse to create a heat gradient from an electric current, it is called a thermoelectric cooler.

<span class="mw-page-title-main">Photovoltaic thermal hybrid solar collector</span>

Photovoltaic thermal collectors, typically abbreviated as PVT collectors and also known as hybrid solar collectors, photovoltaic thermal solar collectors, PV/T collectors or solar cogeneration systems, are power generation technologies that convert solar radiation into usable thermal and electrical energy. PVT collectors combine photovoltaic solar cells, which convert sunlight into electricity, with a solar thermal collector, which transfers the otherwise unused waste heat from the PV module to a heat transfer fluid. By combining electricity and heat generation within the same component, these technologies can reach a higher overall efficiency than solar photovoltaic (PV) or solar thermal (T) alone.

<span class="mw-page-title-main">Radiant heating and cooling</span> Category of HVAC technologies

Radiant heating and cooling is a category of HVAC technologies that exchange heat by both convection and radiation with the environments they are designed to heat or cool. There are many subcategories of radiant heating and cooling, including: "radiant ceiling panels", "embedded surface systems", "thermally active building systems", and infrared heaters. According to some definitions, a technology is only included in this category if radiation comprises more than 50% of its heat exchange with the environment; therefore technologies such as radiators and chilled beams are usually not considered radiant heating or cooling. Within this category, it is practical to distinguish between high temperature radiant heating, and radiant heating or cooling with more moderate source temperatures. This article mainly addresses radiant heating and cooling with moderate source temperatures, used to heat or cool indoor environments. Moderate temperature radiant heating and cooling is usually composed of relatively large surfaces that are internally heated or cooled using hydronic or electrical sources. For high temperature indoor or outdoor radiant heating, see: Infrared heater. For snow melt applications see: Snowmelt system.

<span class="mw-page-title-main">Cold district heating</span> District heating with very low temperatures

Cold district heating is a technical variant of a district heating network that operates at low transmission temperatures well below those of conventional district heating systems and can provide both space heating and cooling. Transmission temperatures in the range of approx. 10 to 25 °C are common, allowing different consumers to heat and cool simultaneously and independently of each other. Hot water is produced and the building heated by water heat pumps, which obtain their thermal energy from the heating network, while cooling can be provided either directly via the cold heat network or, if necessary, indirectly via chillers. Cold local heating is sometimes also referred to as an anergy network. The collective term for such systems in scientific terminology is 5th generation district heating and cooling. Due to the possibility of being operated entirely by renewable energies and at the same time contributing to balancing the fluctuating production of wind turbines and photovoltaic systems, cold local heating networks are considered a promising option for a sustainable, potentially greenhouse gas and emission-free heat supply.

<span class="mw-page-title-main">Passive daytime radiative cooling</span> Management strategy for global warming

Passive daytime radiative cooling (PDRC) is the use of unpowered, reflective/thermally-emissive surfaces to lower the temperature of a building or other object.

References

  1. ↑ Andersson, O.; Hägg, M. (2008), "Deliverable 10 - Sweden - Preliminary design of a seasonal heat storage for IGEIA – Integration of geothermal energy into industrial applications Archived 11 April 2020 at the Wayback Machine , pp. 38–56 and 72–76, retrieved 21 April 2013
  2. ↑ Wong, Bill (June 28, 2011), "Drake Landing Solar Community" Archived 2016-03-04 at the Wayback Machine , IDEA/CDEA District Energy/CHP 2011 Conference, Toronto, pp. 1–30, retrieved 21 April 2013
  3. ↑ Wong B., Thornton J. (2013). Integrating Solar & Heat Pumps. Archived 2013-10-15 at the Wayback Machine Renewable Heat Workshop.
  4. ↑ Paksoy, H.; Stiles, L. (2009), "Aquifer Thermal Energy Cold Storage System at Richard Stockton College" Archived 2014-01-12 at the Wayback Machine , Effstock 2009 (11th International) - Thermal Energy Storage for Efficiency and Sustainability, Stockholm.
  5. 1 2 Kovats, Sari; Brisley, Rachel (2021). Betts, R.A.; Howard, A.B.; Pearson, K.V. (eds.). "Health, Communities and the Built Environment" (PDF). The Third UK Climate Change Risk Assessment Technical Report. Prepared for the Climate Change Committee, London: 38. Although uptake may increase autonomously in the future, relying on air conditioning to deal with the risk is a potentially maladaptive solution, and it expels waste heat into the environment - thereby enhancing the urban heat island effect.
  6. ↑ Chen, Meijie; Pang, Dan; Yan, Hongjie (November 2022). "Colored passive daytime radiative cooling coatings based on dielectric and plasmonic spheres". Applied Thermal Engineering. 216: 119125. Bibcode:2022AppTE.21619125C. doi:10.1016/j.applthermaleng.2022.119125. S2CID   251420566 – via Elsevier Science Direct. One such promising alternative is radiative cooling, which is a ubiquitous process of losing surface heat through thermal radiation. Instead of releasing waste heat into ambient air as conventional cooling systems, radiative cooling passively discharges it into outer space.
  7. ↑ Aili, Ablimit; Yin, Xiaobo; Yang, Ronggui (February 2022). "Passive sub-ambient cooling: radiative cooling versus evaporative cooling". Applied Thermal Engineering. 202: 117909. arXiv: 2107.04151 . Bibcode:2022AppTE.20217909A. doi:10.1016/j.applthermaleng.2021.117909. S2CID   235790365 – via Elsevier Science Direct.
  8. ↑ "Annual Electric Generator Report". U.S. Energy Information Administration. 1 January 2018.
  9. ↑ Fernández-Yáñez, P. (2021). "Thermal management of thermoelectric generators for waste energy recovery". Applied Thermal Engineering. 196 (published 1 September 2021): 117291. Bibcode:2021AppTE.19617291F. doi: 10.1016/j.applthermaleng.2021.117291 .
  10. ↑ "New Technologies' Wasted Energies". CNRS News. Retrieved 6 July 2018.
  11. ↑ Fiala D, Lomas KJ, Stohrer M (November 1999). "A computer model of human thermoregulation for a wide range of environmental conditions: the passive system". J. Appl. Physiol. 87 (5): 1957–72. doi:10.1152/jappl.1999.87.5.1957. PMID   10562642. S2CID   5751821.
  12. ↑ Fernández-Yáñez, P. (2021). "Thermal management of thermoelectric generators for waste energy recovery". Applied Thermal Engineering. 196 (published 1 September 2021): 117291. Bibcode:2021AppTE.19617291F. doi: 10.1016/j.applthermaleng.2021.117291 .
  13. ↑ Gunawan, A; Lin, CH; Buttry, DA; Mujica, V; Taylor, RA; Prasher, RS; Phelan, PE (2013). "Liquid thermoelectrics: review of recent and limited new data of thermogalvanic cell experiments". Nanoscale Microscale Thermophys Eng. 17 (4): 304–23. Bibcode:2013NMTE...17..304G. doi:10.1080/15567265.2013.776149. S2CID   120138941.
  14. ↑ Quoilin, Sylvain; Broek, Martijn Van Den; Declaye, Sébastien; Dewallef, Pierre; Lemort, Vincent (1 June 2013). "Techno-economic survey of Organic Rankine Cycle (ORC) systems". Renewable and Sustainable Energy Reviews. 22: 168–186. doi: 10.1016/j.rser.2013.01.028 . Archived from the original on 3 October 2016. Retrieved 7 May 2018.
  15. ↑ Simone Buffa; et al. (2019), "5th generation district heating and cooling systems: A review of existing cases in Europe", Renewable and Sustainable Energy Reviews , vol. 104, pp. 504–522, doi: 10.1016/j.rser.2018.12.059
  16. ↑ "Glossary of Meteorology". AMS. Archived from the original on 26 February 2009.
  17. ↑ Ritchie, Hannah; Roser, Max; Rosado, Pablo (27 October 2022). "Energy Production and Consumption". Our World in Data. Retrieved 24 March 2023.
  18. ↑ "What is the Surface Area of the Earth?". Universe Today. 11 February 2017. Retrieved 24 March 2023.
  19. ↑ "Heat Island Effect: Glossary". United States Environmental Protection Agency. 2009. Archived from the original on 20 April 2009. Retrieved 6 April 2009.
  20. ↑ Zhang, Xiaochun (2015). "Time scales and ratios of climate forcing due to thermal versus carbon dioxide emissions from fossil fuels". Geophysical Research Letters. 42 (11): 4548–4555. Bibcode:2015GeoRL..42.4548Z. doi: 10.1002/2015GL063514 .
  21. 1 2 Flanner, M. G. (2009). "Integrating anthropogenic heat flux with global climate models" (PDF). Geophys. Res. Lett. 36 (2): L02801. Bibcode:2009GeoRL..36.2801F. CiteSeerX   10.1.1.689.5935 . doi:10.1029/2008GL036465. S2CID   8371380.
  22. ↑ Block, A., K. Keuler, and E. Schaller (2004). "Impacts of anthropogenic heat on regional climate patterns". Geophysical Research Letters . 31 (12): L12211. Bibcode:2004GeoRL..3112211B. doi: 10.1029/2004GL019852 . Archived from the original on 6 June 2011.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  23. ↑ R. Döpel, "Über die geophysikalische Schranke der industriellen Energieerzeugung." Wissenschaftl. Zeitschrift der Technischen Hochschule Ilmenau, ISSN   0043-6917, Bd. 19 (1973, H.2), 37-52. (online).
  24. ↑ H. Arnold, "Robert Döpel and his Model of Global Warming. An Early Warning – and its Update." (2013) online. 1st ed.: "Robert Döpel und sein Modell der globalen Erwärmung. Eine frühe Warnung - und die Aktualisierung." Universitätsverlag Ilmenau 2009, ISBN   978-3-939473-50-3.
  25. ↑ Chaisson, E. J. (2008). "Long-Term Global Heating from Energy Usage" (PDF). Eos. 89 (28): 253–260. Bibcode:2008EOSTr..89..253C. doi: 10.1029/2008eo280001 .
  26. ↑ Cowern, Nick E.B.; Ahn, Chihak (November 2008). "Thermal emissions and climate change: Cooler options for future energy technology". Cowern Science. arXiv: 0811.0476 .
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