Lower Heat Production Research Articles

Waste incineration with production of clean and reliable energy

Discussion about utilization of waste for energy production (waste-to-energy, WTE) has moved on to next development phase. Waste fired power plants are discussed and investigated. These facilities focus on electricity production whereas heat supply is diminished and operations are not limited by insufficient heat demand. Present results of simulation prove that increase of net electrical efficiency above 20% for units processing 100 kt/year (the most common ones) is problematic and tightly bound with increased investments. Very low useful heat production in Rankine-cycle based cogeneration system with standard steam parameters leads to ineffective utilization of energy. This is documented in this article with the help of newly developed methodology based on primary energy savings evaluation. This approach is confronted with common method for energy recovery efficiency evaluation required by EU legislation (Energy Efficiency—R1 Criteria). New term highly-efficient WTE is proposed and condition under which is the incinerator classified as highly efficient are specified and analyzed. Once sole electricity production is compelled by limited local heat demand, application of non-conventional arrangements is highly beneficial to secure effective energy utilization. In the paper a system where municipal solid waste incinerator is integrated with combined gas–steam cycle is evaluated in the same manner.

An automatic gas-phase molecular absorption spectrometric system using a UV-LED photodiode based detector for determination of nitrite and total nitrate

An automatic gas-phase molecular absorption spectrometric (GPMAS) system was developed and applied to determine nitrite and total nitrate in water samples. The GPMAS system was coupled with a UV-light emitting diode photodiode (UV-LED-PD) based photometric detector, including a 255nm UV-LED as the light source, a polyvinyl chloride (PVC) tube of 14cm as the gas flow cell, and an integrated photodiode amplifier to measure the transmitted light intensity. The UV-LED-PD detector was compact, robust, simple and of low heat production, comparing with detectors used in other GPMAS works. For nitrite measurement, citric acid was used to acidify the sample, and ethanol to catalyze the quantitative formation of NO2. The produced NO2 was purged with air flow into the UV-LED-PD detector, and the gaseous absorbance value was measured. The total nitrate could be determined after being reduced to nitrite with a cadmium column. Limits of detection for nitrite and nitrate were 7μmol/L and 12μmol/L, respectively; and linear ranges of 0.021–5mmol/L for nitrite and 0.036–4mmol/L for nitrate were obtained. Related standard deviations were 1.81% and 1.08% for nitrite and nitrate, respectively, both at 2mmol/L. The proposed method has been applied to determine nitrite and total nitrate in some environmental water samples.

The use of excimer laser for complex coronary artery lesions

Excimer laser coronary atherectomy (ELCA) has been used for coronary intervention for more than 20 years. Advances in delivery systems for laser energy using the xenon-chlorine pulsed laser catheter deliver higher energy density with lower heat production. The Spectranetics CVX-300 (Spectranetics, Colorado Springs, CO, USA) excimer laser catheter system has been used for the treatment of complex coronary lesions. We report our experience with the use of this advanced system for stenoses for which were unsuitable for standard percutaneous coronary intervention; for example, balloon-resistant lesions, chronic total occlusions, and for underexpanded stents in calcified lesions. ELCA may also be valuable for thrombus-containing lesion. We find ELCA to be indispensable in the catheterization laboratory for specific complex or calcified lesions. Its role should be explored in a large randomized trial of thrombus containing lesions and saphenous vein grafts.

Scaling of heat production by thermogenic flowers: limits to floral size and maximum rate of respiration

Effect of size of inflorescences, flowers and cones on maximum rate of heat production is analysed allometrically in 23 species of thermogenic plants having diverse structures and ranging between 1.8 and 600 g. Total respiration rate (, micromol s(-1)) varies with spadix mass (M, g) according to in 15 species of Araceae. Thermal conductance (C, mW degrees C(-1)) for spadices scales according to C = 18.5M(0.73). Mass does not significantly affect the difference between floral and air temperature. Aroids with exposed appendices with high surface area have high thermal conductance, consistent with the need to vaporize attractive scents. True flowers have significantly lower heat production and thermal conductance, because closed petals retain heat that benefits resident insects. The florets on aroid spadices, either within a floral chamber or spathe, have intermediate thermal conductance, consistent with mixed roles. Mass-specific rates of respiration are variable between species, but reach 900 nmol s(-1) g(-1) in aroid male florets, exceeding rates of all other plants and even most animals. Maximum mass-specific respiration appears to be limited by oxygen delivery through individual cells. Reducing mass-specific respiration may be one selective influence on the evolution of large size of thermogenic flowers.

Effects of feeding fat on lactation performance of the laboratory mouse, <i>Mus musculus</i>

Laboratory mice (strain MF1) were used to investigate the effects of dietary fat intake on lactation performance. The specific dynamic action (SDA) for high fat (HF), medium fat (MF) and a low fat (LF) diets was measured using open-flow respirometry at 4.5%, 3.9% and 6.1%, respectively. The same three diets were fed ad libitum to mice between days 4 and 18 of lactation. Mice fed HF, MF and LF diets reached plateau in their daily food intake at 14.95±1.14 g day-1, 16.30±0.61 g day-1 and 16.57±0.26 g day-1, respectively between days 12-17 of lactation. At weaning, litters from HF and MF-fed mice were significantly heavier than pups on LF diet. This was because the HF and MF-fed mice not only consumed more energy at peak lactation but also delivered more milk energy to their pups than the LF-fed mice. Evidence suggested that the positive effects of feeding fat to mice were in part due to the low SDA and probably low heat production for milk synthesis. Probably, the ability of the HF and MF-fed mice to directly transfer absorbed fat into the milk might have reduced the heat production of lactogenesis. The HF and MF diets had beneficial effects on lactation because they increased the capacity of mice to generate milk more efficiently and wean heavier offspring than mice fed LF diet. The daily energy expenditure (DEE) of mice in the three dietary groups was fixed.KEY WORDS: Laboratory mouse, dietary fat, specific dynamic action, doubly labelled water, daily energy expenditure, milk energy output, reproductive performance

Practical Application of UV-LED Curing Technology to UV Inkjet

UV-LED curing systems have started to play a larger role in many UV curing applications - including wide format and single pass UV inkjet – and their application and adoption will likely continue to accelerate over the next several years.Adoption is increasing based on the wider availability of suitable UV-LED inkjet ink formulations. The inherent advantages of UV-LED technology - in terms of lifetime, consistency of output, instant on/off and lower heat production, as well as the possibility for systems that are smaller and more robust when compared to existing traditional lamp solution - makes it particularly attractive for UV Inkjet applications.Just like all new technologies there are important differences, distinctions and choices that must be made if a successful implementation is to be achieved. UV-LED curing systems are not the same as traditional mercury vapor lamp systems and the issues of required irradiance/power output, measurement of irradiance/power and understanding of the effects and availability of wavelengths available today in UV-LED are key in making appropriate decisions about the suitability of the technology. These and other system level considerations will be discussed and the paper will outline several successful implementations of UV-LED for inkjet that are currently in the public domain.The paper will also outline the challenges and will share some data and insight into the practical application and efficacy of newer generation UV-LED systems when applied to optimized inks sets for UV Inkjet applications.

Multispectral Image Acquisition with Flash Light Sources

We set up a multispectral image acquisition system using a flash light source and a camera featuring optical bandpass filters. The filters are mounted on a computer-controlled filter wheel between the lens and a grayscale sensor. For each filter wheel position, we fire the flash once within the exposure interval and acquire a grayscale image. Finally, all grayscale images are combined into a multispectral image. The use of narrowband filters to divide the electromagnetic spectrum into several passbands drastically reduces the available light at the sensor. In case of continuous light sources, this requires powerful lamps producing a lot of heat and long exposure times. In contrast, a flashgun emits its energy in a very short time interval, allowing for short exposure times and low heat production. Our detailed colorimetric analysis comparing the color accuracy obtainable with our flashgun and a halogen bulb shows that our acquisition system is well suited for multispectral image acquisition. We computed a mean color error of 1.75 CIE ΔE00 using the flashgun. Furthermore, we discuss several practical aspects arising from the use of flash light sources; namely, the spectrum, repeat accuracy, illumination uniformity, synchronization, and calibration of the system. To compensate for intensity variations of the flash, we propose two calibration methods and compare their performance.

Shoshonites, vaugnerites and potassic lamprophyres: similarities and differences between ‘ultra’-high-K rocks

ABSTRACTA comparative study of three main igneous rock associations that plot in the K2O–SiO2 diagram shoshonite field: shoshonite series absarokites–shoshonites–banakites (henceforth referred to as shoshonites s.l.), vaugnerites, and potassic lamprophyres, reveals that similarities between the associations are superficial. Vaugnerites and lamprophyres are more magnesian, richer in large ion lithophile and high field strength elements and have higher light rare earth/heavy rare earth ratios than shoshonites. Furthermore, shoshonites have low radiogenic heat production, typical of subduction-related rocks, but most vaugnerites and some lamprophyres are highly radioactive. Relative to bulk-Earth, shoshonites have depleted, asthenospheric mantle-like Sr and Nd isotope signatures, whereas vaugnerites and potassic lamprophyres have enriched, crust or lithospheric mantle-like compositions. Though vaugnerites and some lamprophyres show evidence of crustal contamination, the contaminated magma was not originally shoshonitic. Their composition is consistent with derivation from a metasomatised upper mantle source enriched long before melting, thus precluding an active subduction setting. In conclusion, the term shoshonite, implying late-stage arc magmas, cannot be applied to a rock series simply because it plots into the K2O–SiO2 diagram shoshonite field. Shoshonites with a subduction-related source may, however, be identified by discriminant function analysis.

Estimation of heat generation by radioactive decay of some phosphate rocks in Egypt

Radiogenic heat production data for phosphate rocks outcropping on the three main areas Eastern Desert, Western Desert and Nile Valley are presented. They were derived from uranium, thorium and potassium concentration measurements of gamma radiation originating from the decay of 214Bi ( 238U series), 208Tl ( 232Th series) and the primary decay of 40K. A low radioactive heat production rate (0.32±0.1 μW m −3) was found for Wadi Hegaza, whereas the highest value (19±4.1 μW m −3) was found for Gabel Anz, Eastern Desert of Egypt.

Heat production and energy balance of sheep and goats fed sole diets of Acacia saligna and Medicago sativa

We hypothesized that the heat production and energy balance of small ruminants are affected by diet quality, in particular plants with high levels of detrimental secondary compounds, and that there are differences among livestock in the ability to utilize forage. The ability to utilize high tannin fodders would be very important in drylands for livestock production. Energy intake and change in energy balance in sheep ( n = 10; 44.5 kg) and goats ( n = 10; 36.5 kg) were determined when consuming an ad libitum sole diet of either Acacia saligna, a low quality, tannin-rich fodder or Medicago sativa (lucerne hay), a high quality fodder. Dry matter digestibility of A. saligna in goats was higher than in sheep, 44.6 and 25.9%, respectively, but was similar between ruminant species for M. sativa. Daily heat production of goats and sheep when consuming A. saligna was 360.4 and 321.0 kJ kg −0.75 day −1, respectively, and when consuming M. sativa was 432.3 and 445.8 kJ kg −0.75 day −1, respectively. There was no difference between livestock species, but heat production was higher on M. sativa than on A. saligna. Metabolizable energy intake of A. saligna was higher in goats than in sheep, 232.4 and 78.1 kJ kg −0.75 day −1, but there was no difference between goats and sheep when consuming M. sativa. Goats and sheep were in negative energy balance when consuming A. saligna but were in positive energy balance when consuming M. sativa. However, the energy loss in goats was less than in sheep when consuming A. saligna, 128.0 and 242.9 kJ kg −0.75 day −1, respectively, but there was no difference in energy gain between species when consuming M. sativa. Results indicated that (1) the lower heat production when consuming A. saligna than M. sativa is mainly a consequence of the lower dry matter intake and heat increment of feeding; (2) digestibility of high quality forage is similar between goats and sheep, but that goats are better able to digest poor quality forage; and (3) that goats can tolerate higher tannin levels than sheep.

High radiogenic heat production in the Kerala Khondalite Block, Southern Granulite Province, India

In situ radioelemental (K, U and Th) analysis and heat production estimates have been made at 59 sites in the Kerala Khondalite Block (KKB) of the Southern Granulite Province (SGP) of India. Together with the in situ analyses on granulites and gneisses previously reported from 28 sites, and heat production estimated from the published geochemical analyses on granites and syenites of the KKB, the new data set allows good characterization of heat production for the major granulite facies rocks and granitoids of the KKB. Garnet biotite gneisses are characterized by high levels of Th and U, with mean values of 60 and 3 ppm, respectively. Khondalites, leptynites and charnockites have slightly lower levels of Th (23, 20 and 22 ppm, respectively) and U (2.9, 2.4 and 0.9 ppm, respectively). The mean K, U, Th abundances for the granites, leucogranites and granitic gneisses ranges from 3.9 to 4.3%, 2.6 to 4.3 ppm, 22 to 50 ppm respectively, and for the syenites 4.8%, 2 ppm and 5.7 ppm. Mean radiogenic heat production values for garnet–biotite gneiss, khondalite, leptynite and charnockite are 5.5, 2.7, 2.4 and 2.2 μW m−3, respectively. For the granites, leucogranites, granitic gneisses and syenites it is 2.6, 3.4, 4.6 and 1.4 μW m−3, respectively. Heat production of granulite facies rocks, which are the most abundant rocks in KKB, correlate well with Th, but less with U, suggesting that variation is caused by Th and U bearing accessory minerals such as monazite and zircon. The high heat production of the KKB granulites are in contrast to the low heat production of the Late Archaean granulites of the Northern Block (NB) of the SGP which are highly depleted in radioelements and also the granulites of Madurai Block (MB) that have higher radioelemental abundances than in the granulites of the NB. The high heat production of the KKB granulites could be due to the nature of protoliths and/or metasomatism associated with Neoproteroic- to- Pan African alkaline magmatic activity represented by alkali granite and syenite–carbonatite emplacements and emplacement of pegmatites.

Comparison of heat production and plasma lipid metabolites between meat‐ and egg‐types of Nagoya breed chicken during embryonic development

ABSTRACTWe compared heat production (HP) and plasma lipid metabolites between meat‐ and egg‐types of Nagoya breed chickens during embryonic development. To investigate HP and respiratory quotient, oxygen consumption and carbon dioxide production were measured using an open‐circuit calorimeter system. HP was significantly lower in meat‐ than in egg‐type chickens during embryonic development, and HP gradually decreased with developmental stage in both types. The respiratory quotient was constant at approximately 0.68 at every embryonic stage investigated, and the value was similar in both types. Plasma concentrations of triacylglycerol, nonesterified fatty acid, glycerol and D‐3‐hydroxybutyrate, which are associated with lipid metabolism, were similar in both types during embryonic development. These results demonstrate that chicken embryos selected for rapid growth of Nagoya breed have characteristic lower HP, and that when selecting chickens for rapid growth, HP is an important parameter during embryonic stages.

Triiodothyronine differentially regulates key metabolic factors in lean and obese cats

The effect of a 2-week administration of 75 μg triiodothyronine (T3) on substrate oxidation, heat production, non-esterified fatty acids, and leptin was evaluated in eight lean (three females and five males) and eight obese (five females and three males) age-matched adult neutered cats. In addition, using real-time RT-PCR, expression of muscle and adipose tissue uncoupling proteins (UCP2 and UCP3), deiodinase 1 and 2 (D1; D2), and peroxisome proliferator-activated receptor (PPAR) α and γ and peroxisome-proliferator-activator receptor-gamma co-activator 1α (PGC1) was examined. Compared to lean cats, obese cats had increased NEFA, leptin, UCP2, and D1mRNA in muscle and UCP3mRNA levels in fat, but lower heat production, and fat PPARs and PGC1. T3 administration increased thermogenesis and NEFA in lean and obese cats, and adipose tissue PPARγ in lean cats. It also increased muscle D1 in lean and D2 in obese cats. The increase in muscle D2 was interpreted to be reflective of the reduced serum total T4 concentration following T3 suppression of the pituitary. No effect was seen on leptin, or UCP2 and 3. This shows that T3 regulates thermogenesis but not through changes in uncoupling protein expression. It also indicates that PPARs have an important role in the pathogenesis of obesity in cats.

Protein Levels for Heat-Exposed Broilers: Performance, Nutrients Digestibility, and Energy and Protein Metabolism

Heat stress causes significant economic losses on broilers production due to poorer performance and carcass quality. Considering that protein has the highest heat increment among nutrients, it has been suggested that protein levels should be reduced in diets for heat-exposed broilers. Nevertheless, there are no conclusive results on the benefits of such practice, and further studies should be performed to elucidate some reported discrepancies. Thus, a trial was carried out to evaluate the effects of dietary protein levels (17, 20 and 23%) and environmental temperature (22 and 32oC) on the performance, nutrients digestibility, and energy and protein metabolism of broiler chickens from 21 to 42 days of age. Nutrients digestibility was determined by total excreta collection, and energy and protein metabolism was evaluated by comparative slaughter method. It was concluded that (1) heat exposure impairs broilers performance and increases nitrogen excretion, but do not change nutrients digestibility; (2) high-protein diets are technically feasible and promotes lower heat production for broilers reared under thermoneutral or hot environments, however, highprotein diets increases nitrogen excretion.

Thermal ecology of Interior Alaska dragonflies (Odonata: Anisoptera)

Summary We examined the thermal ecology of Interior Alaska dragonflies (Odonata: Anisoptera). The relationships between mass and passive cooling rate, wing loading, minimum flight temperature (MFT) and thermoregulating ability were examined. These properties were also compared between the behavioural classes: perchers and fliers. All factors with the addition of seasonal and daily flight activity were related to generalized thermal strategies. Passive cooling rate decreased while wing loading and MFT increased with mass. While all species were able to elevate thoracic temperature, larger species were better able to maintain a constant temperature. Both the smallest and largest species of dragonflies were capable of activity at ambient temperatures of approximately 14 °C by employing different thermal strategies: low MFT and physiological heat production, respectively. For small species active in cool conditions low MFT may be favoured even if accompanied by poor thermoregulating ability. By contrast, thermoregulation and specialization for high‐temperature performance may be favoured in both small and large species during the warmer summer flight season. The smallest and largest dragonflies in Interior Alaska have the shortest and longest daily activity periods, respectively. However this pattern does not hold for the intermediate‐sized dragonflies. Thermal strategy displays no clear relationship to daily activity pattern.

Physiological and Metabolic Aspects of Very Prolonged Exercise with Particular Reference to Hill Walking

Hill walking is a popular recreational activity in the developed world, yet it has the potential to impose severe stress simultaneously upon several regulatory systems. Information regarding the physiological strain imposed by prolonged walking outdoors in adverse climatic conditions was reported almost four decades ago and recent research has extended some of this work. These data indicate that once the walker fatigues and starts to slow or stops walking altogether, the rate of heat production falls dramatically. This decrease alone predisposes to the development of hypothermia. These processes, in adverse weather conditions and/or during periods when the level of exertion is low (with low heat production), will be accelerated. Since the majority of walkers pursue this activity in groups, the less fit walkers may be more susceptible to fatigue when exercising at a higher relative intensity compared with their fitter counterparts. The best physiological offset for hypothermia is to maintain heat production by means of exercise, and so fatigue becomes a critical predisposing factor; it is as important to facilitate heat loss, especially during periods of high exertion, as it is to maintain heat production and preserve insulation. This can be partly achieved by clothing adjustments and consideration of the intensity of exercise. Failure to provide adequate energy intake during hill walking activities has been associated with decreased performance (particularly with respect to balance) and impaired thermoregulation. Such impairments may increase susceptibly to both fatigue and injury whilst pursuing this form of activity outdoors. The prolonged low to moderate intensity of activity experienced during a typical hill walk elicits marked changes in the metabolic and hormonal milieu. Available data suggest that during hill walking, even during periods of acute negative energy balance, blood glucose concentrations are maintained. The maintenance of blood glucose concentrations seems to reflect the presence of an alternative fuel source, a hormonally induced increase in fat mobilisation. Such enhancement of fat mobilisation should make it easier to maintain blood glucose by decreasing carbohydrate oxidation and promoting gluconeogenesis, thus sparing glucose utilisation by active muscle. During strenuous hill walking, older age walkers may be particularly prone to dehydration and decreased physical and mental performance, when compared with their younger counterparts. In summary, high rates of energy expenditure and hypohydration are likely to be closely linked to the activity. Periods of adverse weather, low energy intake, lowered fitness or increased age, can all increase the participants' susceptibility to injury, fatigue and hypothermia in the mountainous environment.

An overview of adakite, tonalite–trondhjemite–granodiorite (TTG), and sanukitoid: relationships and some implications for crustal evolution

Examination of an extensive adakite geochemical database identifies two distinct compositional groups. One consists of high-SiO 2 adakites (HSA) which is considered to represent subducted basaltic slab-melts that have reacted with peridotite during ascent through mantle wedge. The second group consists of low-SiO 2 adakites (LSA) which we interpret to have formed by melting of a peridotitic mantle wedge whose composition has been modified by reaction with felsic slab-melts. The chemical composition of less differentiated (primitive) Archaean tonalite–trondhjemite–granodiorite (TTG) magmas evolved from 4.0 to 2.5 Ga. Mg# (molecular Mg/(Mg+Fe 2+), Ni, and Cr contents increased over this period of time and we interpret these changes in terms of changes in the degree to which the TTG magmas interacted with mantle peridotite. Over the same period, concentrations of (CaO+Na 2O) and Sr also increased, as the amount of plagioclase, residual from basalt melting, decreased in response to increased pressures at the site of slab-melting. In the Early Archaean, it appears that these interactions were very rare or absent thus leading to the conclusion that subduction was typically flat and lacked the development of a mantle wedge. In contrast, the relatively lower heat production by ∼2.5 Ga meant that slab-melting occurred at greater depth, where plagioclase was no longer stable, and where the development of a thick mantle wedge ensured interaction between the slab-melts and mantle peridotite. Close compositional similarities between HSA and Late Archaean TTG ( T<∼3.0 Ga) strongly suggest a petrogenetic analogy. However, an analogy between the older Archaean TTG and HSA is not complete because evidence for mantle wedge interaction is missing in most Early Archaean TTGs. Late Archaean sanukitoids and the compositionally similar Closepet-type granites have compositions significantly different from TTG of all ages. However, they show some affinity with LSA which could be considered as their possible analogue. These magmas are all thought to result from melting of a mantle peridotite whose composition has been modified by reaction with slab-melts. We propose that all these magmas are directly linked to slab-melting. Archaean TTG and HSA represent slab-melts that have interacted with peridotite to varying extent, whereas sanukitoids, Closepet-type granites, and LSA correspond to melts of peridotite previously metasomatised by slab-melt. The changes observed from Early Archaean TTG to Late Archaean TTG and to sanukitoids reflect change in both the nature and efficiency of interaction between slab-melt and mantle wedge peridotite. Comparisons between all of these rocks suggest that ancient styles of subduction that have operated since at least ∼3.3 Ga persist in a limited way today. The secular changes in the degree and style of these interactions is a direct consequence of the cooling of Earth that modified the thermal and dynamic parameters at the subducted slab–mantle wedge interface.

Assessment of heat production, heat loss, and core temperature during nitrous oxide exposure: a new paradigm for studying drug effects and opponent responses

Studies using core temperature (T(c)) have contributed greatly to theoretical explanations of drug tolerance and its relationship to key features of addiction, including dependence, withdrawal, and relapse. Many theoretical accounts of tolerance propose that a given drug-induced psychobiological disturbance elicits opponent responses that contribute to tolerance development. This proposal and its theoretical extensions (e.g., conditioning as a mechanism of chronic tolerance) have been inferred from dependent variables, such as T(c), which represent the summation of multiple underlying determinants. Direct measurements of determinants could increase the understanding of opponent processes in tolerance, dependence, and withdrawal. The proximal determinants of T(c) are metabolic heat production (HP) and heat loss (HL). We developed a novel system for simultaneously quantifying HP (indirect calorimetry), HL (direct gradient layer calorimetry), and T(c) (telemetry) during steady-state administrations of nitrous oxide (N(2)O), an inhalant with abuse potential that has been previously used to study acute and chronic tolerance development to its hypothermia-inducing property. Rats were administered 60% N(2)O (n = 18) or placebo gas (n = 16) for 5 h after a 2-h placebo baseline exposure. On average, N(2)O rapidly but transiently lowered HP and increased HL, each by approximately 16% (P < 0.001). On average, rats reestablished and maintained thermal equilibrium (HP = HL) at a hypothermic T(c) (-1.6 degrees C). However, some rats entered positive heat balance (HP > HL) after becoming hypothermic such that acute tolerance developed, i.e., T(c) rose despite continued drug administration. This work is the first to directly quantify the thermal determinants of T(c) during administration of a drug of abuse and establishes a new paradigm for studying opponent processes involved in acute and chronic hypothermic tolerance development.

Thermal modeling of the UHP Maksyutov Complex in the south Urals

Two-dimensional thermal modeling of the subduction and exhumation of the ultrahigh-pressure (UHP) Maksyutov Complex in the south Ural Mountains tests factors influencing the low modern heat flow in the Urals and the feeble preservation of UHP index minerals. Best-fit models are obtained with initial surface heat flow of 60 mW m−2 indicating that low modern heat flow in the Urals is a recent anomaly. Ultrahigh-pressure metamorphism was modeled at 388 Ma based on new U–Pb SHRIMP dating of zircon; the average modeled exhumation rate for the UHP eclogites to the mid-crust is ∼5.0 mm/year, much slower than other UHP complexes. The model predicts that cooling during exhumation is strongly dependent on concomitant subduction/underthrusting in the footwall of the UHP unit and normal faulting in the hanging wall. Low radiogenic heat production in the crust and a relatively thin UHP slab (3–10 km) also favor cooling. For Maksyutov, the modeling shows that cooling was controlled by low radiogenic heat production and underthrusting during decompression to lower crustal levels; these cooling mechanisms accompany exhumation despite low exhumation rates (∼5 mm/year) thereby denying the call for fast exhumation in order to preserve UHP index minerals.

Modelling a district heating system: Introduction of waste incineration, policy instruments and co-operation with an industry

The capacity for waste incineration in Swedish municipalities is increasing due to regulations aimed at decreasing landfill with waste. This has a large impact on the municipal energy systems, since waste is an important fuel for district heating production. The object of this study is a municipality, Skövde, which is planning to build a waste incineration plant to produce electricity and heat. The municipality is also planning to extend the district heating grid to include a large industrial heat consumer. The economic effect on the energy system of these measures is analysed as well as environmental effects in terms of carbon dioxide emissions. The consequences of two different policy instruments, green electricity certificates and a tax on waste incineration, are also studied. Economic optimisations show that the advantage of co-operation with industry is twofold: lower heat production costs and a considerable reduction of carbon dioxide emissions. It is economically feasible to invest in a waste incineration plant for heat production. An important measure to lower carbon dioxide emissions is to introduce combined heat and power production on the assumption that locally produced electricity replaces electricity produced by coal condensing power.