The effect of wind power forecasts on balancing power pricing:case Finland

Abstract. In European electricity systems, more and more electricity is produced from renewable energy sources, and in Finland, particularly from wind power. Wind power is intermittent by nature. Most wind power is sold in day-ahead markets, where the sellers are basing their bids on weather forecasts. The intermittency of wind power is expected to shift the trading from day-ahead markets to closer to real time markets, such as intraday and balancing power market markets. This thesis studies the impact of wind power forecast errors, i.e., the surplus or deficit of the actual production compared to the forecasted volume, on the balancing power market prices in Finland. Using data from January 2017 to January 2021, we use the general additive model to study the inference between wind power surplus and the balancing power premium, defined as a difference between the price in the balancing power market and the day-ahead market, to estimate the effect. The main finding is that for up-regulation the balancing power premia respond negatively to wind surplus, and positively for down-regulation, even when controlling for other covariates. To estimate the magnitude of the effect of wind surplus, we calculated the predicted values of balancing power price premium at the 5th and 95th percentiles of wind surplus for both up- and down-regulation. For up-regulation, the predicted values based on the sample, are 30.1 €/MWh and 16.01 €/MWh. For down-regulation, the predicted values based on the sample, were -16.0 €/MWh and -12.0 €/MWh for the 5th and 95th percentiles respectively. Both the results are economically significant.Tuulivoimaennusteiden vaikutus säätösähkön hinnoitteluun : case Suomi. Tiivistelmä. Eurooppalaisissa sähköjärjestelmissä yhä suurempi osa sähköstä tuotetaan uusiutuvan energian tuotantomuodoilla. Suomessa erityisesti tuulivoiman osuus on kasvanut, ja sen odotetaan yhä kasvavan tulevina vuosina. Tuulivoiman tuotanto on luonteeltaan epäsäännöllistä. Suurin osa tuulivoimalla tuotetusta sähköstä myydään vuorokausimarkkinoilla, jolloin tuulivoiman tuottajat perustavat myyntitarjouksensa seuraavan päivän tuotantoennusteisiin. Tuulivoiman epäsäännöllisestä luonteesta johtuen päivänsisäisten markkinoiden ja säätösähkön markkinoiden odotetaan kasvattavan painoarvoaan suhteessa perinteisiin vuorokausimarkkinoihin. Tämä opinnäytetyö tarkastelee tuulivoiman ennustevirheitä, toisin sanoen tuulivoiman yli- tai alituotantoa ennusteeseen verrattuna, ja näiden virheiden vaikutusta säätösähkön markkinahintoihin Suomessa. Käytetty data on vuosilta 2017- 2021, ja vaikutusten arviointiin käytetään epälineaarista GAM-menetelmää (Generalized Additive Methods), jolla arvioidaan tuulivoiman ennustevirheen vaikutusta säätösähkön hinnan ja vuorokausimarkkinahinnan erotukseen, eli niin sanottuun säätösähkön hintapreemioon. Pääasiallinen tutkimustulos on, että ylössäädössä tuulivoiman positiivisen ennustevirheen vaste säätösähkön hintapreemioon on negatiivinen, ja alassäädössä vastaavasti positiviinen, vaikka muut kovariaatit on kontrolloitu. Tuulivoiman ennustevirheen vaikutuksen suuruuden arvioimiseksi laskettiin arvioidut säätösähkön hintapreemiot 5. ja 95. prosenttipisteille. Ylössäädön osalta hintapreemiot ovat 30,1 €/MWh ja 16,0 €/MWh. Alassäädölle preemiot ovat vastaavasti -16.0 €/MWh ja -12,0 €/MWh. Molemmat tulokset ovat taloudellisesti merkitsevi

Effect of Carbon Nanotube Aqueous Dispersion Quality on Mechanical Properties of Cement Composite

An effect of the quality of carbon nanotube (CNT) dispersions added to cement on paste mechanical properties has been studied. High-quality dispersions of few-walled CNT (FWCNTs) were produced in two steps. First, FWCNTs were functionalized in a mixture of nitric and sulfuric acids (70 wt.% and 96 wt.%, resp.) at 80 ∘C . Second, functionalized FWCNTs were washed out by acetone to remove carboxylated carbonaceous fragments (CCFs) formed during CNT oxidation. Mechanical test results showed 2-fold increase in the compressive strength of the cement paste prepared from the dispersion of acetone-washed functionalized FWCNTs, which is believed to occur due to the chemical interaction between cement matrix and functional groups (–COOH and –OH). Utilisation of unwashed FWCNTs led to a marginal improvement of mechanical properties of the cement pastes, whereas surfactant-treated functionalized FWCNT dispersions only worsened the mechanical properties.Peer reviewe

Synthesis of Carbon Nanotubes and Nanofibers on Silica and Cement Matrix Materials

In order to create strong composite materials, a good dispersion of carbon nanotubes (CNTs) and nanofibers (CNFs) in a matrix material must be obtained. We proposed a simple method of growing the desirable carbon nanomaterial directly on the surface of matrix particles. CNTs and CNFs were synthesised on the surface of model object, silica fume particles impregnated by iron salt, and directly on pristine cement particles, naturally containing iron oxide. Acetylene was successfully utilised as a carbon source in the temperature range from 550 to 750 C. 5–10 walled CNTs with diameters of 10–15 nm at 600 C and 12–20 nm at 750 C were synthesised on silica particles. In case of cement particles, mainly CNFs with a diameter of around 30 nm were grown. It was shown that high temperatures caused chemical and physical transformation of cement particles.Peer reviewe

A novel cement-based hybrid material

Carbon nanotubes (CNTs) and carbon nanofibers (CNFs) are known to possess exceptional tensile strength, elastic modulus and electrical and thermal conductivity. They are promising candidates for the next-generation high-performance structural and multi-functional composite materials. However, one of the largest obstacles to creating strong, electrically or thermally conductive CNT/CNF composites is the difficulty of getting a good dispersion of the carbon nanomaterials in a matrix. Typically, time-consuming steps of purification and functionalization of the carbon nanomaterial are required. We propose a new approach to grow CNTs/CNFs directly on the surface of matrix particles. As the matrix we selected cement, the most important construction material. We synthesized in a simple one-step process a novel cement hybrid material (CHM), wherein CNTs and CNFs are attached to the cement particles. The CHM has been proven to increase 2 times the compressive strength and 40 times the electrical conductivity of the hardened paste, i.e. concrete without sand.Peer reviewe

Human cytomegalovirus tegument protein pp65 is detected in all intra- and extra-axial brain tumours independent of the tumour type or grade

Human cytomegalovirus (HCMV) has been indicated being a significant oncomodulator. Recent reports have suggested that an antiviral treatment alters the outcome of a glioblastoma. We analysed the performance of commercial HCMV-antibodies applying the immunohistochemical (IHC) methods on brain sample obtained from a subject with a verified HCMV infection, on samples obtained from 14 control subjects, and on a tissue microarray block containing cores of various brain tumours. Based on these trials, we selected the best performing antibody and analysed a cohort of 417 extra- and intra-axial brain tumours such as gliomas, medulloblastomas, primary diffuse large B-cell lymphomas, and meningiomas. HCMV protein pp65 immunoreactivity was observed in all types of tumours analysed, and the IHC expression did not depend on the patient's age, gender, tumour type, or grade. The labelling pattern observed in the tumours differed from the labelling pattern observed in the tissue with an active HCMV infection. The HCMV protein was expressed in up to 90% of all the tumours investigated. Our results are in accordance with previous reports regarding the HCMV protein expression in glioblastomas and medulloblastomas. In addition, the HCMV protein expression was seen in primary brain lymphomas, low-grade gliomas, and in meningiomas. Our results indicate that the HCMV protein pp65 expression is common in intra- and extra-axial brain tumours. Thus, the assessment of the HCMV expression in tumours of various origins and pathologically altered tissue in conditions such as inflammation, infection, and even degeneration should certainly be facilitated

Heme oxygenase-1 repeat polymorphism in septic acute kidney injury

Abstract Acute kidney injury (AKI) is a syndrome that frequently affects the critically ill. Recently, an increased number of dinucleotide repeats in the HMOX1 gene were reported to associate with development of AKI in cardiac surgery. We aimed to test the replicability of this finding in a Finnish cohort of critically ill septic patients. This multicenter study was part of the national FINNAKI study. We genotyped 300 patients with severe AKI (KDIGO 2 or 3) and 353 controls without AKI (KDIGO 0) for the guanine–thymine (GTn) repeat in the promoter region of the HMOX1 gene. The allele calling was based on the number of repeats, the cut off being 27 repeats in the S–L (short to long) classification, and 27 and 34 repeats for the S–M–L₂ (short to medium to very long) classification. The plasma concentrations of heme oxygenase-1 (HO-1) enzyme were measured on admission. The allele distribution in our patients was similar to that published previously, with peaks at 23 and 30 repeats. The S-allele increases AKI risk. An adjusted OR was 1.30 for each S-allele in an additive genetic model (95% CI 1.01–1.66; p = 0.041). Alleles with a repeat number greater than 34 were significantly associated with lower HO-1 concentration (p<0.001). In septic patients, we report an association between a short repeat in HMOX1 and AKI risk