Evaluation of cold thermal energy storage in fishing vessels

Depending on the operational mode, fishing vessels and fish transporting well-boats have varying cooling demands. There is a possible benefit of peak shaving and energy saving with the use of cold thermal energy storage (CTES), which has been explored in this paper. Fishing vessels have limited space availability and the focus is therefore on compact and efficient systems. A CO2 system is suitable for that purpose due to its compactness and high volumetric refrigeration capacity. One application is to use ice slurry systems, which can be used to reduce the storage temperature of the fish and thereby keep the fish quality longer, compared with no chilling or chilling in refrigerated seawater (RSW). The chilling rates are faster and there is no significant damage to the fish surface. In this study, theoretical calculations were conducted to find the requirements of an ice slurry system according to the reference conditions of the studied case. The calculation model was built using the thermodynamic properties of ice and fish.acceptedVersio

Energy consumption of ammonia refrigeration system on board a fishing vessel

When assessing the carbon footprint of seafood from capture fisheries, the fuel use during fishing operation is the major contributor to overall greenhouse gas emissions. While the necessary shift towards low-carbon fuels and advancement in propulsion technology has commenced, also a more efficient use of energy is a key strategy for reduction of the emissions. Furthermore, leakage of high-GWP refrigerants contributes to emissions and a transition towards natural refrigerants (NH3, CO2) is essential. Introducing efficiency measures depends on knowledge of current performance. Due to the wide range of different fishing vessels with different on-board processing equipment and different modes of operation, the performance needs to be evaluated for each fleet segment before proper advise can be given. This paper presents energy measurement results from a research cruise conducted during autumn 2020 on a combined purse seiner/pelagic trawler. The vessel's refrigeration system was instrumented with sensors logging the electrical input to frequency converters (compressors and seawater pumps) and temperatures on the RSW side, while the vessels mode of operation and fuel consumption was logged on a regular basis during the cruise. The results provide insight on the vessel's energy flow, performance of the refrigeration system and fuel intensity of the fishing operation, which gives valuable input for design of efficiency measures.acceptedVersio

Energy flow analysis of an industrial ammonia refrigeration system and potential for a cold thermal energy storage

There is an increasing effort to reduce energy demand at food processing plants, mainly to reduce the total carbon footprint. The energy demand of a fish processing plant (using ammonia as refrigerant) has been evaluated in this study. Results show that production follows a seasonal cycle throughout the year, with no (or very low) production in the spring (Mar-May), and peak production in the autumn (Sep-Nov). By investigating data from the plant's energy management system, it was revealed that the refrigeration systems are responsible for about 75% of the total electric power demand and the compressors for 90-95% of that. Because of the large discrepancy in energy demand over the year, and also daily variation within production periods, there is a good potential for installing a cold thermal energy storage. An initial evaluation on how a CTES system can be implemented at the plant is included, discussing type of storage, choice of PCM (e.g. solid CO2) and effect on heat production, but this evaluation will be developed further.Energy flow analysis of an industrial ammonia refrigeration system and potential for a cold thermal energy storageacceptedVersio

Dietary replacement of fishmeal with marine proteins recovered from shrimp and herring process waters promising in Atlantic salmon aquaculture

There is a general agreement that fish meal (FM) and fish oil (FO) are valuable resources for aquafeed, but that the production cannot keep the same pace as the current growth of the aquaculture industry. Therefore, there is a need to find alternative sources for lipids and protein. This study examines the possibility of using proteins recovered from seafood industry side stream waters as a complement to FM in feed for Atlantic salmon. To recover the proteins, herring and shrimp process side streams waters were flocculated then treated with dissolved air flotation (DAF), which is considered a gentle technology. Shrimp steam water was used to obtain shrimp protein (SP) and herring salt brine to obtain herring protein (HP). The recovered semi-solid protein fraction was spray dried and formulated into experimental diets at inclusion levels of 1.9–10% (dw/dw). Two feeding trials were conducted to investigate; 1) the properties of different flocculants to recover SP from shrimp steam water, alginate (Alg; 1.9% inclusion), carrageenan (Carr; 2.0% inclusion) and a synthetic flocculant from Kemira (Kem; 3.8% inclusion). 2) total or partial replacement of FM with SP-Alg (10% and no FM) and HP-Alg (3% and 8% FM). For both feeding trials each diet was provided to triplicate tanks (n = 31 and 30/tank) of Atlantic salmon with a start weight of 193 g (duration 10 weeks) and 304 g (duration 7 weeks) respectively. All fish showed similar feed intake, feed conversion ratio (on tank basis) and weight gain. The inclusion of SP or HP as total or partial replacement of FM did neither influence adiposity of the fish, as measured by condition factor, nor heposomatic index (HSI). No negative effect of the alternative protein could be found through histological examination of the intestine. In feeding trial two, diets did not affect the adaptive immune indicators CD8α and MHC II. The SP-Alg diet did not affect intestinal barrier and transporting functions, assessed using Ussing-chamber technology. However, HP-Alg affected the trans-epithelial resistance, which indicate that the intestinal barrier function could be affected by low inclusions. We conclude that from a biological perspective, SP recovered from shrimp steaming waters using Alg and DAF technology represents a new marine biomass with potential as a replacement for FM in Atlantic salmon feed. To diversify the possibility of using flocculants to retrieve proteins we also suggest further investigation of the potential to use Carr in larger inclusions

Veileder - Industrielle konsepter for refresh produkter av hvitfisk

En refresh-produksjon henviser til produkter som har vært fryst, lagret og tint en eller flere ganger gjennom verdikjeden fra fangst til butikk. En vanlig metode for en refresh-produksjon av hvitfisk er å produsere konsumentforpakninger av filet eller loins som fryses, transporteres og deretter tines nært utsalgsstedene [13,16,18]. En annen tilnærming er å fryse inn porsjoner i blokk eller IQF (individuelt raskt frosset), for deretter å tine og pakke produktene nært markedet (Se figur 1, s.4). Det norske fisket etter torsk er sesongbasert. Hovedtyngden av volumet landes i løpet av årets første måneder i perioden januar til april. Sesongvariasjonene skaper utfordringer for ferskfiskindustrien som er avhengig av jevn produksjon. Markedet ønsker stabile leveranser slik at forbrukerne kan tilbys torsk hele året. En løsning på dette er å fryse fisken i høysesong for deretter å tine og selge "refresh"-produkter utenfor sesong [4,13,18]. Refresh-produksjon kan gi flere fordeler knyttet til holdbarhet og matsvinn, mer miljøvennlig distribusjon, lavere distribusjonskostnader, jevn og høy kvalitet og mer stabile leveranser. Norsk industri ønsker også å øke andelen innenlands foredling fremfor å eksportere fisk til prosessering i utlandet. Refresh-produksjon kan bidra til dette. I dag er den kun en norsk industriell aktør som har en slik produksjon, men flere industriaktører er interessert i å starte opp. Skal det satses ytterligere på en slik produksjon, er det avgjørende at den beste teknologien og produksjonskonseptene blir benyttet. Fersk selvfangstet fisk eller fisk som man kjøper direkte fra fisker har selvsagt den ideelle kvaliteten så lenge den har blitt optimalt behandlet. Men, med utgangspunkt i råstoff av høy kvalitet og god kunnskap om innfrysing, lagring og tining kan man også produsere tinte produkter av høy kvalitet også utenom høysesong. Denne veilederen oppsummerer "best practice" for en refresh-produksjon basert på kunnskapsstatus og resultater fra FHF prosjektet ReFresh (Kartlegging og optimalisering av industrielle konsepter for refresh-produkter av hvitfisk, prosjektnr 901596).FHF - Fiskeri– og havbruksnæringens forskningsfinansieringpublishedVersio

Development of a Antibacterial Disc Diffusion Assay to Differentiate Fusarin C from Non-Fusarin C activity in Early Screening of Mutant Fusarium graminearum Extracts

The discovery of novel compounds with antibacterial properties continues to be critically important.3 One potential source of such compounds is the cryptic genome of fungi known to produce biologically active molecules. A kmt6 mutant of the cereal pathogen Fusarium graminearum was previously developed through a histone H3 lysine 27 methyltransferase gene knockout, and has been shown to express hundreds of additional genes compared to wild type under the same growth conditions.1 Both the kmt6 mutant and the wild type F. graminearum produce the biologically active metabolite fusarin C, shown in Figure 1, and its analogs. Activity due to fusarin C can mask any activity of non-fusarin C compounds during early screening of extracts. Using a broad panel of bacteria, two samples were tested for differentiating activity profiles. These included an ethyl acetate extract of kmt6 growth media (i.e., the “160001E” fraction), and a more purified flash column fraction containing fusarin C and its analogs (i.e., the “fusarin C isolate”). Intriguingly, both Bacillus cereus and Staphylococcus aureus were inhibited by the 160001E extract, but were not inhibited by the fusarin C isolate. This indicates that activity from the 160001E fraction is not due to fusarin C or its analogs, but rather due to non-fusarin C compounds. With these results, a panel of 5 bacteria, including both gram negative and gram positive strains, has been developed as an early screening tool to differentiate activity between fusarin C isolates and non-fusarin C compounds from kmt6 mutant F. graminearum. This will aid in the bioassay-guided fractionation of extracts exhibiting antibacterial activity due to non-fusarin C compounds and toward the important aim of identifying novel compounds with antibacterial activity

Sykefravær og arbeidsstabens sammensetning: En empirisk analyse av Trondheims kommunale barnehager

Sykefraværet i Trondheims kommunale barnehager har de siste årene vært bekymringsfullt høyt, og det er store variasjoner i sykefraværet mellom barnehagene. Å finne årsaker og løsninger til det høye fraværet er derfor et viktig forskningsområde for kommunen. Formålet med denne oppgaven er å undersøke i hvilken grad det er en sammenheng mellom bemanningssammensetningen og sykefraværet i Trondheims kommunale barnehager. Vi bruker månedsdata fra 56 barnehageenheter, fra januar 2018 til desember 2020. Først estimerer vi en modell basert på hele utvalget. Vi finner da en sammenheng mellom sykefraværet i enhetene og forklaringsvariablene antall ansatte og andel menn. Et annet viktig resultat er at sykefraværet kan reduseres betydelig dersom man finner hvilke forhold som forårsaker de store variasjonene i sykefraværet mellom enhetene. Deretter estimerer vi fire modeller hvor hver modell er et delutvalg av enhetene. Delutvalgene er konstruert etter gjennomsnittssykefravær og standardavvik. Vi finner at bemanningssammensetning ikke påvirker sykefraværet i enheter med lavt gjennomsnittlig sykefravær, men at det derimot er en sammenheng mellom bemanningssammensetning og sykefravær i enheter med høyt gjennomsnittssykefravær. Dette kan skyldes at det er andre forhold som forklarer hvorfor noen enheter har lavt sykefravær, og hvordan disse enhetene organiserer arbeidsstaben blir derfor relativt ubetydelig. Videre finner vi resultater som tyder på at bemanningssammensetning har størst effekt i enheter med høyt gjennomsnittlig sykefravær og lav variasjon. Vi konkluderer også med at den store variasjonen i sykefravær mellom enhetene ikke kan skyldes forskjeller i bemanningssammensetningen, og at det trolig ikke finnes én "riktig" bemanningssammensetning som isolert sett minimerer sykefraværet i alle enhetene