Promocijas darbs

Elektroniskā versija nesatur pielikumusJau iepriekš ir bijuši eksperimentālie pētījumi, kuros tika mērītas sūnas un novērtēts to pieaugums, tomēr savā promocijas darbā realizēju sūnu skenēšanas metodes aprobāciju. Sūnu skenēšanas metode tika veikta tāpēc, lai turpmākos pētījumos nevajadzētu veikt katra sūnas segmenta atsevišķu parametru (segmenta stumbra un zaru) mērīšanu, kas ir laika un darba ietilpīgs process. Veicot Hylocomium splendens skenēšanas efektivitates novērtēšanu secināts, ka segmenta virsmas laukums būtiski korelēja ar segmentu svaru un arī ar zaru garumu, bet nebūtiska korelācija bija ar sūnas segmentu stumbra mērījumiem. Pēc sūnas dinamikas pētījuma rezultātiem acīmredzot varētu ieteikt sūnu bioindikācijai ņemt tikai trīs jaunākos H. splendens pieauguma gada segmentus. Zinot to, ka sūnas stumbram ir vairāki šūnu slāņi nekā sūnas lapā, tad tāpēc tika veikts laboratorijas eksperiments, kurā pārbaudījām seriālās ekstraģēšanas efektivitāti, nosakot ķīmisko elementu koncentrācijas dažādās sūnu šūnu frakcijās un sūnas daļās. No šī eksperimenta secināts, ka šī metode ir nepiemērota Ca un Mg daudzuma novērtēšanai stumbra audos atsevišķās sūnu šūnu frakcijas daļās, kā arī to, ka sūnas stumbrs var būt tikai kā ūdens un barības vielu rezervuārs, un stumbrs ir tikai kā ceļš K+ jonu kustībai un nevis kā kālija avots priekš šīs kustības. Stumbram, salīdzinot ar sūnas zariem, lielāka ir arī rezistence pret izkalšanu, kas var nodrošināt mazākus elementu zudumus. Promocijas darba mērķis bija noskaidrot Hylocomium splendens nozīmi, kas ir kā viena no priežu meža ekosistēmas komponenta sastāvdaļām un, izmantojot sūnas, novērtēt vides piesārņojuma līmeni visā Latvijas teritorijā. Veicot mākslīgus traucējumus ekosistēmā novērojām, ka pat pēc 4,5 gadiem sūnu stāva traucētajos parauglaukumos, kur noņēma sūnu stāvu, pilnībā nesasniedza sākotnējos biomasas apjomus, kā arī to, ka sūnu stāva transformācija būtiski neietekmēja ķīmisko elementu koncentrāciju izmaiņas Vaccinium myrtillus lapās un Picea abies skujās. Sūnu pārstādīšanas eksperiments starp dažādas pakāpes piesārņojuma vietām (piesārņoto un nepiesārņoto) parādīja, ka notiek ķīmisko elementu izlīdzināšanās ar jaunajiem vides apstākļiem, tas ir, liela ir elementu absorbcijas kapacitāte, kā arī to, ka sūnās esošo ķīmisko elementu koncentrāciju neietekmē zem tā esošais substrāts. Bez tam arī šie eksperimenti parādīja, ka pārstādīšanas procesā radītais stress neietekmē sūnas augšanas intensitāti. Novērtējot atmosfēras vides piesārņojumu visā Latvijas teritorijā secināts, ka nedaudz paaugstinātas smago metālu koncentrācijas sūnās konstatētas ap Liepāju (Zn, Pb, Cd, Cr), Brocēniem (Cu, V, Zn), Olaini (V, Cd), Rīgu (Cd), Daugavpili (V), tomēr vidējās ķīmisko elementu koncentrācijas sūnās Latvijā atbilst Ziemeļeiropas nepiesārņoto reģionu līmenim. Retrospektīvi analizējot smago metālu daudzumu sūnā novērots, ka Latvijā samazinās smago metālu, izņemot Cd, Zn un Cu, izsēšanās no atmosfēras. Smago metālu koncentrāciju izmaiņas Latvijā galvenokārt ir izskaidrojamas arī ar ekonomiskajām izmaiņām, un tas ir tāpēc, ka lielās ražotnes tika slēgtas vai nu vispār, vai arī tās ir samazinājušas savu ražošanas jaudu.Though earlier experimental studies including measuring mosses and estimating their growth have been made already, still I exercised approbation of moss scanning methods during my own promotion work. Moss scanning method was applied with a view to avoid measuring of separate parameters of each moss segment (stem and branches of a segment) that would comprise time-consuming and labour-intensive works in further studies. Through assessment of scanning effectiveness of Hylocomium splendens mosses it was concluded that surface area of a segment strongly correlated with weight of the segment and also length of branches, but there was insignificant correlation with stem measurements of moss segments. Based on results of moss dynamics study it could be advised to take only three younger annual segments of H. splendens moss growth for moss bioindication evidently. Knowledge of the fact that moss stem consists of more cell layers than a moss leaf was the reason why we carried out laboratory experiment during which we tested effectiveness of serial extraction by determining concentration of chemical elements in different fractions of moss cells and parts. It was concluded from this experiment that this method was not appropriate for estimating content of Ca and Mg in stem cells within separate fraction parts of moss cells, and moss stem might serve only as a reservoir of water and nutrients and the stem was just a pathway for K ions movement instead of being K source for this movement. Compared to sprigs the stem is more resistant to desiccation thus being able to ensure less element losses. The aim of the promotion work was to determine significance of Hylocomium splendens moss which was one of the components within pine forest ecosystem, and by using the mosses to assess environmental pollution degree on the entire territory of Latvia. Having made artificial disturbances within the ecosystem we observed that mosses did not reach the absolute previous amounts of biomass even in 4,5 years within disturbed sample plots where the moss cover was removed, as well as transformation of the moss cover had weak influence on changes in concentration of chemical elements in spruce needles and bilberry bushes. The experiment of transplanting mosses among places with different pollution degree (polluted and non-polluted) showed that evening out of chemical elements with the new habitat conditions was taking place, i.e., capacity of element absorption was great, and that content of chemical elements present in mosses was not affected by the substrate underneath them. Moreover, these experiments also showed that the stress caused by transplanting process did not affect intensity of moss growth. By studying atmospheric environmental pollution on the entire territory of Latvia it was concluded that slightly increased concentration of heavy metals in mosses were detected around Liepaja (Zn, Pb, Cd, Cr), Broceni (Cu, V, Zn), Olaine (V, Cd), Riga (Cd), Daugavpils (V), still the average concentration of chemical elements in mosses in Latvia corresponded to the degree of non-polluted regions in Northern Europe. Through retrospective analysis of amount of heavy metals in mosses it was observed that deposition of heavy metals from the atmosphere in Latvia decreased, except Cd, Zn and Cu. Changes in concentrations of heavy metals in Latvia are generally explained by economic changes, and this is due to complete closing of large manufactures or decreased production volume there

Methodology for Calculation of the Marginal Emission Rates from a ComplexCogeneration Facility compared with that of the co-located NY ISO Bus

Cogeneration facilities at commercial and institutional locations are significant emitters carbon dioxide. Many large universities, hospitals and large commercial complexes maintain combined heat and power facilities that are interfaced with wholesale power markets. These facilities both buy and sell electricity in the organized markets while maintaining what is their principle function of provision of thermal energy for heating and cooling. In this paper we provide the theoretical background to calculation of Marginal Emission Rates (MERs), provide an overview of the optimal operation of those facilities, and present the results of a detailed case analysis of the results of a comparison of the MER of an operating cogeneration facility at Cornell University compared with the MER for consumption of electricity at the closest wholesale bus of the New York Independent System Operator (NYISO)

A Wake-Up Call for the Utility Industry: Extreme Weather and Fundamental Lessons from 2021

We have examined the critical extreme weather events of 2021 that resulted in disruptions of normal power system operations, the loss of life, and multibillion dollar losses to the US economy. These impacts occurred due to extreme cold, extreme heat, drought, slower post-landfall dissipation of hurricanes, and more intense large-scale thunderstorm systems. We point to the causes but also argue for the changes in planning and operations required to be prepared for and have responses to these events. Specifically, we focus on recognizing the reality of extreme events and planning for their increasing frequency, intensity, duration, and geographic scope; modifying resource planning and adequacy metrics to incorporate common mode events; enabling the power system to depend on reliable natural gas fuel supplies; redesigning power markets to better compensate resources and flexible demand for reducing the probability of outages; and developing resilient systems

Application of sector and location specific models of the "worth" of renewable energy technologies

Renewable energy sources such as solar and wind hold the potential for providing a significant portion of the U.S. energy requirements in the decades ahead. Unlike other energy sources their availability is determined by nonrandom events beyond the control of the consumer. In addition, macro-, meso-, and microclimatic conditions play a major role in determining the worth of such renewable energy sources to their owners. The worth of these new technologies will be a function of owner, location, and application as well as the traditional capital and operating cost, i.e., their worth to an owner in the southwest will be different form that to an owner in the northeast or the southeast. Dealing with energy sources, with geographic and sectorally specific energy values and with energy technologies with which we have little or no experience in the marketplace has created a set of challenges in analysis and modeling of these new technologies in competition with traditional energy technologies and with other emerging technologies. This paper will look at one simulation methodology for estimating the worth of renewable energy systems providing electricity, such as wind or solar photovoltaic power systems, and will discuss the interaction between such systems and traditional electric utilities with which they may or may not be integrated, be owned or be co-located. The paper concludes with a discussion of the issues associated with the incorporation of econometric techniques into such a simulation modeling structure

The economics of water lifting for small scale irrigation in the third world: |b traditional and photovoltaic technologies

Previously issued as MIT Energy Laboratory Working paper # MIT-EL-78-015wp, August 1978.Much of the non-traditional, irrigated, agricultural land in developing nations utilizes pumping technologies which have been adapted from the developed nations. These technologies are adaptable to the medium and large scale farms (individual farms in excess of 2 hectares) but are not adaptable to smaller farms. It has been these larger third world farmers who have been able to take the fullest advantage of the benefits of new seed varieties in wheat and rice combined with fertilizer and water, the ingredients of the "green revolution." This short paper summarizes the experience to date of developing water pumping systems for small farms in selected deltaic areas of the 'third world,' those areas in which irrigation water is available at depths between 1.5 and 4.5 meters (m). These areas include the Nile, Euphrates, Indus, Ganges, Irrawaddy, and Mekong River Basins which combined encompass 50 million hectares of the earth's surface (less than one percent of the earth's land area) and contain roughly 250 million people (nearly 7 percent of the world's population). The analyses evaluate water supplied by traditional means--human and animal--by conventional systems--diesel, gasoline and electric--and by renewable resource systems, in particular photovoltaic powered systems. A review of previous studies indicate that the value of water for irrigation is in the range of two to three cents (U.S.) per cubic meter (m3). The methods of lifting water, available to farmers on land areas of one hectare or less, provide water at costs in excess of this two to three cents (U.S.) per m3. Investigations of the Shadoof systems of North Africa and Asia show costs of water as high as seven cents (U.S.) per cubic meter. An evaluation of animal power used to operate a Persian wheel resulted with water costs that varied with the amount of feed required by the animal from 1 to 4/m3. Four pumping systems were investigated using conventional power systems: two diesel, one gasoline, and one electric. Since pumping systems have relatively fixed sizes and prices, the costs generally exceed the benefits for the small farmer. The cost per cubic meter for irrigating one hectare averaged: 3.5¢ (U.S.) for diesel in Chad; 4.0¢ (U.S.) for gasoline in Chad; 3.5Q (U.S.) for diesel in India; and 3.0t (U.S.) for electricity in India. In each of these instances, the cost of supplying small scale farmers with water using conventional systems was greater than the economic value of the water supplied. A fifth pumping system investigated herein utilized a high technology power system, photovoltaic cells combined with efficient electric motor and pump devices. The cost of providing water utilizing the photovoltaic power system resulted in costs of 2.8t/m3 (U.S.) to lift the water 1.5m and 5.44/m3 (U.S.) for lifting heads of 4.5m, at today's cell prices ($10/Wp). If photovoltaic power system costs are reduced to$4.00 per peak watt (Wp), the cost of irrigation water for a lift of 1.5m would be 1.2¢/m3, and for a lift of 4.5m would be 2.3*/m3

The Impact of Distributed Energy Resources on the Bulk Power System: A Deeper Dive

solar photovoltaics (PV), electric storage and electric \ vehicles, demand response, combined heat and \ power, wind, fuel cells, and micro-turbines are \ typically installed on the low or medium voltage \ distribution network. Changes on the distribution \ network can have rippling effects throughout the rest \ of the power system. In this paper, we have \ calculated both traditional locational marginal \ prices (LMPs) and distributed locational marginal \ prices (DLMPs) using an optimal power flow (DC \ OPF). This paper provides an analysis of the energy \ price impacts resulting from significant additions of \ Distributed Energy Resources (DER), namely solar \ PV, electric batteries and demand response, in a \ distribution feeder. The impact is measured in terms \ of nodal approximations to DLMPs, realistic \ calculation of LMPs in the transmission system and \ overall price suppression effects that trickle down to \ consumers on the feeder. Policy implications are \ drawn concerning the potential impacts of \ penetration of DER on future planning, and \ operation of the power system as well as on energy \ markets and the environment