Lisardo Núñez-Regueira

Calorific values and flammability of forest species in Galicia. Coastal and hillside zones

Abstract Changes in heat values and in flammability with the seasons of the year for the different species which make up the woodland map of two zones, Sada (coastal area) and Santiago (hillside and plateau area), situated in La Coruna (Galicia, Spain), are reported. These data were evaluated as a help for fighting forest fires, which have been very frequent in this region during the last decade. The species studied are the most abundant in the areas: Eucalyptus globulus Labill., Pinus pinaster Aiton, Ulex europaeus L., Rubus fructicosus L., Pteridium aquilinum L., Sarothamnus scoparius (L.) Link, Quercus robur L., Castanea sativa Miller and Acer pseudoplatanus L. The calorific values were measured by static bomb calorimetry. These data were complemented with flammability determinations and completed with chemical analyses of the different species.

Calorific values and flammability of forest species in Galicia. Continental high mountainous and humid Atlantic zones

Abstract Calorific value, flammability and chemical composition during the seasons of the year for the different forest species which make up the woodland map of two zones, Devesa da Rogueira (continental high mountainous zone) and As Neves (humid atlantic zone), situated in Galicia (Spain), are reported. The species characteristic of the zones are: Sorbus aucuparia L., Acer pseudoplatanus L., Taxus baccata L., Fagus sylvatica L., Quercus robur L. and Castanea sativa Miller. in Devesa da Rogueira (Orense), and: Alnus glutinosa (L.) Gaertner., Betula celtiberica L., Prunus avium (L.) L., Fraxinus excelsior L., Laurus nobilis L. and Salix Atrocinera L. , in As Neves (La Coruāna). The calorific values were measured by static bomb calorimetry and the flammability using a method proposed by Valette.

Energy evaluation of forest residues originated from shrub species in Galicia

In this study we present an alternative for the management of the excess of shrub species that nowadays take up around 800000 ha in Galicia (NW Spain). This alternative is based on the exploitation of the energetic resources contained in the excess of shrubs by their combustion in specially designed plants for production of electric energy. The different species were sorted into three groups: Ulex europaeus L. (furze), Sarothamnus scoparius (L.) Link (broom) and Erica sp. (heaths). Their LHV were calculated through measurements of the corresponding HHV and resulted 7600, 7300 and 7200 kJ kg(-1) respectively. Biomass productions (T ha(-1)) were also calculated resulting 20 T ha(-1) (furze), 30 T ha(-1) (broom), and 15 T ha(-1) (heaths). Analyses of all these values make these species very valuable for their energy exploitation. Samples were collected over one year in different zones to study the effect of the environmental conditions on the calorific values.

Energy evaluation of forest residues originated from Eucalyptus globulus Labill in Galicia.

The possibility of retrieving the energy contained in forest residues originating from wood exploitation in Galicia (Spain) is evaluated. This study was made on Eucalyptus globulus Labill occupying a forest surface of 240000 ha. This species plays an important role in the economical development of Galicia, as it is the main forest species for production of pulp. Sampling was made over 1999 in seven different zones, three main stations plus four selected for comparison, situated in Galicia. The residues originating from cutting were sorted into three different groups and their calorific values were measured by static bomb calorimetry. These calorific values, close to 7200 kJ kg(-1), make possible the use of this residual biomass as an energy source. Calorific values were measured by static bomb calorimeter in an oxygen atmosphere. Flammability was determined using a standard epiradiator. Simultaneously, some other parameters, elementary chemical composition, heavy metal contents, moisture, density, ash percentage after combustion in the bomb, and main bioclimatic characteristics, were also determined.

The influence of some physicochemical parameters on the microbial growth in soils

Abstiact Microcalorimetric techniques have been used to study the influence of different physicochemical parameters on microbial growth in different soils in Galicia (NW Spain). The study was carried out using a 4 channels Thermal Activity Monitor (Thermometric, Sweden). Two types of soil, humic cambisol and umbric regosol, with different uses, vineyard, orchard, maize field, and scrubland, were investigated. Microbial activity in all the soils studied was stimulated by the addition of 1.25 mg of glucose g - 1 soil. The power-time curves recorded from every experiment were analysed and from these analyses characteristic parameters such as peak time, peak height and microbial growth rate constants were determined. The influence of different environmental parameters, temperature (ambience and soil), moisture content (sample and residual), pH in water, and C/N ratio, were considered.

Energy evaluation of forest residues originated from pine in Galicia.

Pine residues originated from cuts and forestry tasks were studied with the main objective of using them as an alternative source of energy. Calorific values were measured using a static bomb calorimeter in an oxygen atmosphere. From these measurements a value of 7500 kJkg(-1) for the mean lower heating value of these kind of residues was found. A rational and sustainable exploitation of the calorific energy contained in these residues can yield a gross benefit of 2.8 x 10(8) per year through its transformation in electric energy. The study was made along one year, using samples collected in different previously characterized zones. Some other parameters such as: elementary composition, heavy metal content, flammability, and bioclimatic properties were also determined.

Effect of storage of soil at 4°C on the microbial activity studied by microcalorimetry

The effect of the storage of soils on their microbial activity has been studied using a microcalorimetric method. Soil samples were kept in closed polyethene bags at 4°C during 3–6 months. Results show changes in the slope of the differentP−t curves recorded from the samples stored at 4°C. This fact strongly suggest the existence of changes of the microbial activity of soil as the heat evolution is a direct measurement of the cells metabolic activity. The value of the Peak-time (time in which the microcalorimetric signal reaches the maximum value) is related with the microbial density of soil samples. This parameter was affected by the time of storage increasing with time. The total heat evolutionQ(t), of the soil samples amended with glucose calculated from the area limited by the Power-Time curves, also decreases with the time of storage. The soil that had been stored for 6 months before experiments, showed the lowest valu ofQ(t).ZusammenfassungMittels einer mikrokalorimetrischen Methode wurde der Einfluß der Lagerung von Böden auf ihre mikrobielle Aktivität untersucht. Bodenproben wurden bei 4°C über 3 bis 6 Monate hinweg in verschlossenen Polyethylenbeuteln gelagert. Die Ergebnisse zeigen eine Änderung des Anstieges der verschiedenenP−t Kurven, die von den bei 4°C gelagerten Proben aufgenommen wurden. Diese Tatsache lä\t stark auf die Existenz von Veränderungen der mikrobiellen Aktivität des Bodens schlie\en, da die Entwicklung von Wärme eine unmittelbare Me\möglichkeit für die metabolitische Aktivität der Zellen darstellt. Der Wert der Peak-Zeit (bei der das mikrokalorimetrische Signal sein Maximum erreicht) wird mit der Mikrobendichte der Bodenproben verglichen. Dieser Parameter ist abhängig von der Lagerungsdauer und steigt mit zunehmender Dauer an. Die anhand des von denP−t Kurven begrenzten Fläche berechnete totale WärmeentwicklungQ(t) der mit Glukose ergänzten Bodenproben sinkt mit zunehmender Lagerungsdauer. Bodenproben, die vor den Versuchen 6 Monate lang gelagert wurden, wiesen die geringstenQ(t)-Werte auf.

Energetic Evaluation of Biomass Originating from Forest Waste by Bomb Calorimetry

Calorific values and flammability changes during a year for forest waste originating from silviculture task in Galicia (NW Spain) are reported. These waste materials are becoming to be used as alternative fuels.The present study was made on several hardwood forest species. These forest species occupy nowadays approximately 30% of the total forest surface of Galicia.Calorific values were measured by static bomb calorimeter in an oxygen atmosphere. Flammability was determined using a standard epiradiator. Simultaneously, some other parameters such as elementary chemical composition, heavy metal contents, moisture, density, ash percentage after combustion in the bomb, and main bioclimatic characteristics, were also determined.

Design of risk index maps as a tool to prevent forest fires in the humid Atlantic zone of Galicia (NW Spain)

Abstract In previous articles, we set the basis for the determination of risk indices of forest biomass of Galicia. With this aim, calorific values, flammability, density, moisture contents, ash percentage after combustion, elementary chemical composition, and heavy metal contents over the seasons of the year for the different species which make up the woodland map of a given zone were determined. In the present paper, these studies were applied to this humid Atlantic zone situated in Galicia (NW Spain). The special climatic characteristics of the humid Atlantic zone chosen for our study make its vegetal community singularly gifted. The calorific values of combustion at 25°C were measured by static bomb calorimetry for the different forest species existing in the zone. These data were complemented with flammability values, measured by an epiradiator and completed with chemical analyzes. Some biological and climatic properties necessary for our calculations were taken from available literature. A combined study of all these parameters led to calculation of risk indices of the forest species of the zone over the year. The knowledge of the seasonal risk indices can be very helpful to prevent and fight forest fires effectively, and also for a rational management and exploitation of the forest resources through the obtention of xyloenergy.

Design of risk index maps as a tool to prevent forest fires.: Continental high mountainous zone of Galicia (NW Spain)

Risk indices for the different forest species existing in a high mountainous zone situated in Galicia (NW Spain) as well as their seasonal evolution were studied. Calculation of these risk indices was based on the previous elaboration of energy maps from mean calorific values, flammabilities and chemical analyses of forest species. A combined study of energy maps, bioclimatic characteristics of the zone and main biological properties of the different species led to the determination of the seasonal risk indices. Knowledge of risk indices of the species allows the design of maps to be used to prevent and/or fight forest fires.