Helsingin Energia

Helsinki, Finland

Helsingin Energia

Helsinki, Finland

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Sipila J.,Helsingin Energia | Auerkari P.,VTT Technical Research Center of Finland | Holmstrom S.,Joint Research Center Petten | Vela I.,BAM Federal Institute of Materials Research and Testing
Risk Analysis | Year: 2014

Early warning or leading indicators are discussed for unexpected incidences in case of large-scale underground coal storage at a power plant. The experience is compared with above-ground stockpiles for which established procedures are available but where access for prevention and mitigation are much easier. It is suggested that while the explicit organization, procedures, and the general safety systems aim to provide the targeted levels of performance for the storage, representing new technology without much precedence elsewhere in the world, the extensive experience and tacit knowledge from above-ground open and closed storage systems can help to prepare for and to prevent unwanted incidents in the underground storage. This kind of experience has been also found useful for developing the leading or early warning indicators for underground storage. Examples are given on observed autoignition and freezing of coal in the storage silos, and on occupational hazards. Selection of the leading indicators needs to consider the specific features of the unique underground facility. © 2014 Society for Risk Analysis.


Kymalainen M.,University of Helsinki | Makela M.R.,University of Helsinki | Hilden K.,University of Helsinki | Kukkonen J.,Helsingin Energia
European Journal of Wood and Wood Products | Year: 2015

Storage is a challenging stage in the supply chain of any solid biofuel, as they readily absorb moisture. Increased moisture content (MC) bears many negative consequences, such as biological degradation, reduced heating value and worker health problems. A five-month storage trial served to determine how certain properties of torrefied wood, charcoal and thermally treated pellets change when exposed to natural weathering in a covered and uncovered storage area. Biological degradation and changes in MC and composition were recorded. The pellets also underwent a durability test. Different fungi were isolated from the stored samples and the genus of selected isolates was identified with internal transcribed spacer polymerase chain reaction. Significant changes were detected in the carbon content of the wood material following the trial. The samples in the uncovered storage area had absorbed substantial amounts of water and, after incubation, 99 % of these samples showed visible fungal growth, compared to only 20 % of the covered samples. The pellets showed varying responses to storage in terms of durability and moisture absorption, with the steam explosion pellets possessing more favourable properties than torrefied and untreated pellets. © 2015, Springer-Verlag Berlin Heidelberg.


Korpinen L.,Tampere University of Technology | Kuisti H.,Fingrid Oyj | Paakkonen R.,Finnish Institute of Occupational Health | Vanhala P.,Helsingin Energia | Elovaara J.,Fingrid Oyj
Annals of Occupational Hygiene | Year: 2011

The aim of the study was to measure occupational exposure to electric and magnetic fields during various work tasks at switching and transforming stations of 110 kV (in some situations 20 kV), and analyze if the action values of European Union Directive 2004/40/EC or reference values of International Commission on Non-ionizing Radiation Protection (ICNIRP) were exceeded. The electric (n = 765) and magnetic (n = 203) fields were measured during various work tasks. The average values of all measurements were 3.6 kV m -1 and 28.6 μT. The maximum value of electric fields was 15.5 kV m -1 at task 'maintenance of operating device of circuit breaker from service platform'. In one special work task close to shunt reactor cables (20 kV), the highest magnetic field was 710 μT. In general, the measured magnetic fields were below the reference values of ICNIRP. © 2011 The Author.


Sipila J.,Helsingin Energia | Auerkari P.,VTT Technical Research Center of Finland | Heikkila A.-M.,VTT Technical Research Center of Finland | Krause U.,Otto Von Guericke University of Magdeburg
Journal of Risk Research | Year: 2013

The risk and prevention of autoignition in underground coal storage facilities are reviewed in the light of the recent incidents of smouldering fires. Also, the opportunities are considered on the efficiency of the alternatives to prevent and extinguish closed-space fires. The complexities in avoiding and extinguishing underground fires are highlighted in the case example, describing the observations and outcome of a smouldering coal fire in the storage. The principles of self-heating and most critical factors in spontaneous combustion such as the condition and quality of coal are fairly well known, but usually only provide partial help in fire prevention. The documented cases and the case example suggest that nitrogen injection can be useful for extinguishing controllable fires. Three-phase foams and oxygen-displacing exhaust gases appear preferable against uncontrolled fires, particularly if access to the fire area is limited or impossible. Otherwise, efficient fire extinction during power plant operation can be challenging, as any air ingress tends to feed the fire and results in losses of the extinguishing agent and the heating value of coal. Methods and indicators for detecting and predicting the ignition are discussed, and improvements are suggested to enhance the storage and plant availability. © 2013 Taylor and Francis Group, LLC.


Judl J.,Finnish Environment Institute | Koskela S.,Finnish Environment Institute | Korpela T.,Tampere University of Technology | Karvosenoja N.,Finnish Environment Institute | And 2 more authors.
Energy | Year: 2014

The EU's energy sector depends heavily on fossil fuels, which contribute to climate change. This is why climate mitigation targets for energy production have been set, including an increased biomass use requirement. In Finland, biomass is commonly utilised but its capital, Helsinki, is still dependent on fossil fuels. With the ambition of becoming climate neutral by 2050, Helsinki is testing, inter alia, low-share wood pellet and coal co-combustion in a CHP (combined heat and power) plant. The objectives of this paper were to assess the net environmental impacts of the co-combustion and changes in urban air quality connected to pellet transport, and to identify environmental hotspots relevant to possible future higher-share co-combustion. The applied methods were screening LCA (life cycle assessment) and fine particle dispersion modelling. The results prove that low-share wood pellet co-combustion in CHP production leads to net environmental impact reductions and does not deteriorate air quality in the urban environment. If higher-share co-combustion were to be implemented, the environmental hotspots to focus on would be the operational issues of a power plant and the origin and sustainability aspects of wood pellet production. © 2014 Elsevier Ltd.


Sipila J.,Helsingin Energia | Sipila J.,Aalto University | Auerkari P.,VTT Technical Research Center of Finland | Holmstrom S.,VTT Technical Research Center of Finland | And 2 more authors.
Journal of Fire Sciences | Year: 2012

Self-heating of coal depends partly on intrinsic, coal-related factors. This article aims to discuss the Smith-Glasser index as a potential indicator of the self-heating propensity of a large set of bituminous coals with similar heating value but different origins. For this purpose, recorded properties and experience were reviewed for 7.5 million tonnes of coal delivered to the same power plant operator. The results suggest that the propensity to self-heat can be conveniently indicated by Smith-Glasser index that only involves routinely measured moisture and volatile contents of coal. The results appear consistent with the observed incidences of self-heating in storage. © The Author(s) 2012.


Santasalo-Aarnio A.,Aalto University | Lokkiluoto A.,Helsingin Energia | Virtanen J.,Aalto University | Gasik M.M.,Aalto University
Journal of Power Sources | Year: 2016

One of the largest obstacles for SO2 depolarized electrolyser (SDE) commercialization is the material stability in rough operating conditions. In this work stainless steel bipolar plates have been coated with thin Au layer having bifunctional role: providing electrocatalytic surface for both electrode reactions and simultaneously improves the stainless steel support corrosion tolerance at the potential window of SDE. The stability and performance of the coated bipolar plates were tested in a bench-scale electrolyser set-up and the results indicate that these plates can be utilized as economic catalyst for SDE, moreover, they show corrosion resistance in SDE operation. © 2015 Elsevier B.V.


Sipila J.,Helsingin Energia | Sipila J.,Aalto University | Auerkari P.,VTT Technical Research Center of Finland | Heikkila A.-M.,VTT Technical Research Center of Finland | And 5 more authors.
Journal of Loss Prevention in the Process Industries | Year: 2012

While the self-heating and spontaneous combustion of coal is a known challenge at coal mines and storage sites, there are known methods for mitigating this challenge for typical open stockpile storage. However, closing the storage will reduce access for corrective action, and it is then important to manage the storage and its transport system with added attention without unduly adding cost or hindering availability. This paper aims to discuss the risk, prevention and extinguishing of fires in closed coal storage facilities, particularly in light of the experience with the Salmisaari underground rock storage facility in Finland. The observed autoignition events have indicated an array of contributing factors, some of which are unique to underground silo storage facilities. On the other hand, many features of the storage facilities can be compared with other extant closed storage systems. The factors affecting fire risk are described and the associated fault and event trees are outlined for autoignition at underground storage. Drawing upon the experiences with past events of self-heating and spontaneous combustion, recommendations are given on cost-effective preventive, corrective and other mitigating action for minimising fire risk and promoting storage availability. © 2012.


Sipila J.,Helsingin Energia | Sipila J.,Aalto University | Auerkari P.,VTT Technical Research Center of Finland | Holmstrom S.,VTT Technical Research Center of Finland | And 2 more authors.
Cold Regions Science and Technology | Year: 2012

A coal freezing incident in the underground coal storage of the Salmisaari power plant in Helsinki represents a unique risk factor in terms of the contributing mechanisms. Filling with subzero temperature coal in winter froze silo drains with seepage water, resulting in its leakage into the silo to form large lumps of icy coal that blocked the fuel discharge system. Compared to any previous experience with freezing of coal in transport or storage, including closed storage silos, the unexpected direction of heat transfer from storage wall to coal means an additional challenge in its mitigation, for example, by application of freeze conditioning agents. To assess the accompanying risk and options, the strength of the frozen coal has been modelled from the expected behaviour bounded by the extremes of moisture content. Based on this strength model and realistic distributions of the input variables, a Monte Carlo analysis has been used to assess the expected strength of frozen coal under the local winter climatic conditions. The results suggest that the strength of frozen coal in the discharge hoppers is typically strong to render immediate remedial action tedious and thus explain the challenge to the plant operation. © 2012 Elsevier B.V.


PubMed | Helsingin Energia
Type: Journal Article | Journal: Risk analysis : an official publication of the Society for Risk Analysis | Year: 2015

Early warning or leading indicators are discussed for unexpected incidences in case of large-scale underground coal storage at a power plant. The experience is compared with above-ground stockpiles for which established procedures are available but where access for prevention and mitigation are much easier. It is suggested that while the explicit organization, procedures, and the general safety systems aim to provide the targeted levels of performance for the storage, representing new technology without much precedence elsewhere in the world, the extensive experience and tacit knowledge from above-ground open and closed storage systems can help to prepare for and to prevent unwanted incidents in the underground storage. This kind of experience has been also found useful for developing the leading or early warning indicators for underground storage. Examples are given on observed autoignition and freezing of coal in the storage silos, and on occupational hazards. Selection of the leading indicators needs to consider the specific features of the unique underground facility.

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