19th European Biomass Conference and Exhibition, 6-10 June 2011, Berlin, Germany

FOREST BIOMASS RESOURCES FOR INDUSTRIAL ENERGY CONVERSION IN PORTUGAL Monteiro, C.a, Tarelho, L. a, Lopes, M. a, Monteiro, A. a, Machado, L. b, Amaral, J. b, Borrego, C a. CESAM & Department of Environment and Planning, University of Aveiro, 3810-193 Aveiro, Portugal b RAIZ Research Institute of Forest and Paper, 3801-501 Aveiro, Portugal Corresponding author: C. Monteiro, e-mail: [email protected], Tel: +351 234370220, Fax: +351 234370309 a

ABSTRACT: In recent years, pressures on global environment and energy security have led to an increasing demand on renewable energy sources, and diversification of world’s energy supply. Among these resources the biomass could exert an important role, since it is considered a renewable and CO2 neutral energy resource, and can potentially provide energy for heat, power and transport fuels. The option for biomass to energy has to be sustainable, that is, the level of biomass consumption should not be higher than the level of natural production capacity of ecosystems. In this sense, it is important that appropriate studies of biomass availability and sustainability support strategies of biomass to energy. However, little is known about the availability of the amount of biomass in Portugal. In this scope, and considering the need to have information about this scenario of biomass to energy, and its implications on the Portuguese climate policy, it was initiated a study in order to characterize and quantify the biomass available from the Portuguese forest to energy purposes. The results showed that the existing residual forest biomass estimated is enough to feed the existing and planned thermal power plants in Portugal. Keywords: Biomass, forest, resources, energy.

1

biofuels[3]. Amongst renewable resources paramount importance has been given to the bioenergy because it has low negative environmental impact in terms of CO2 emissions for the entire fuel cycle and zero CO2 emissons from fossil fuels during operation. Since according to the EU White Paper [4], biomass energy is versatile, because it can be used to produce electricity, heat or as fuel for transport as required and, unlike electricity, can be stored in a simple and usually economically. Moreover, the production can vary from small scale up to several MW. The strongest incentive of EU towards development of biomass energy was given in 2005 with the Biomass Action Plan [5]. In this plan, the EU stated that the increased use of renewable energy is essential for environmental and competitiveness reasons, and recognized that: “biomass has many advantages over conventional energy sources, as well as over some other renewable energies, in particular, relatively low costs, less dependence on shorterm weather changes, promotion of regional economic structures and provision of alternative sources of income for farmers” [5]. The Portuguese government defined a strategy of biomass to energy in 2006, with the launch of a program with the objective of increase the national capacity of electricity production from biomass. This program included the achievement of an installed capacity of 250 MWe by 2010, and the construction of fifteen new thermal power plants (corresponding to an installed capacity of 100 MWe). The new power plants location were define by the Portuguese government with the double objective of increasing the quota of renewable energy in the global production of electricity and to promote the development of forest residues harvesting. This will also serve to remove shrub competition on forest groves and reduce wildfire hazard [6]. The Figure 1 presents the distribution of planned thermal power plants in Portugal and their respective power production (MVA), using GIS tools [7].

INTRODUCTION

Emissions of greenhouse gases have grown with industrialization, and particularly from the burning of fossil fuels, such as coal and petroleum to power industry, to heat, cool and transport. After fossil fuels combustion, deforestation is the second largest source of carbon dioxide emissions into the atmosphere [1]. In the last few years some international agreements, like Kyoto Protocol, have been written up in order to reduce the atmospheric emissions of gases that are thought to contribute to global warming. In relation to carbon dioxide emissions, the forest has a double importance: firstly, they are considered a major sink for atmospheric carbon dioxide [2], and secondly the energy use of residual forest biomass would reduce additional emissions of CO2 from fossil fuels combustions. Since 1990, the EU has been engaged in an ambitious and successful plan to become a world leader in renewable energy production and use. The strategic energy plans and policies of the EU, as well as those individual member states, established concrete targets for exploitation of indigenous renewable energy sources (RES), and for bioenergy in particular. In December 2008 an extensive package of measures, referred Package "Energy-Climate" (or Packet 20-20-20) as adopted, which aims to reduce GHG emissions by 20% compared to 1990, to reduce the energy consumption by 20% through increased efficiency, and a 20% share of renewable in gross final energy consumption of up to 2020. This policy package also sets a target quota of energy from renewable in gross final consumption of energy for Portugal of 31% by 2020. Further stipulates that each Member State must ensure a quota of at least 10% energy from renewable in final energy consumption in transport in which the contribution of biofuels from wastes, residues, non-food cellulosic material and wood-cellulosic material is considered to be twice the contribution of other

535

19th European Biomass Conference and Exhibition, 6-10 June 2011, Berlin, Germany

Figure 3 - Distribution of forest stands in Portugal [8].

Figure 1 - Distribution of planned thermal power plants in Portugal [7].

The option for biomass to energy has to be sustainable, that is, the level of biomass consumption should not be higher than the level of natural production capacity of ecosystems. In this sense, it is important that appropriate studies of biomass availability and sustainability support policies of biomass to energy [9]. At the moment little is known about the availability of a sufficient amount of biomass in Portugal to supply the existing industries that consume biomass intensively (power plants, pulp and paper industries and furniture industries) plus the new thermal power plants to be constructed. Considering the need to have information about this scenario of biomass to energy, and its implications on the Portuguese climate policy, it was initiated a study in order to characterize and quantify the biomass available from the Portuguese forest to energy purposes.

After this concurrence only two plants (Belmonte and Palser) are in operation [7]. Actually there are nine thermal power plants and nine cogeneration plants corresponding to an installed capacity of 210MVA. Portugal, given the location and natural resources of its territory, is a country with potential for the exploration of renewable energy sources. Portuguese land is wellsuited for forest growth and have a small amount of suitable soils for agriculture. In Portugal forests cover approximately 3.4 million hectares and represents 38% of the national territory (Figure 2, Figure 3) [8].

2

METHODOLOGY

In this scope, and considering the need to have information about this scenario of biomass to energy, and its implications on the Portuguese climate policy, it was initiated a study in order to characterize and quantify the biomass available from the Portuguese forest to energy purposes. To proceed to such characterization, and in result of the lack of a systematized base of information dedicated to this issue, it was decided to initiate the work based on the National Forest Inventory (NFI) from 20052006 [8]. The NFI contains information about the distribution of forest species by area, densities and age classes, among other data. Based on that information, and using GIS tools it was determined the following information for five tree species (Eucalyptus globulus, Pinus pinaster, Pinus pinea, Quercus ilex, Quercus suber), considered most suitable for energy conversion:

Figure 2 - Areas by land use in Portugal (103 ha) [8]. The main tree species which are widely planted for commercial purposes and capable for of providing a regular supply to meet fuel demand are Eucalyptus globulus, Pinus pinaster, Pinus pinea, Quercus ilex, Quercus suber.

536

19th European Biomass Conference and Exhibition, 6-10 June 2011, Berlin, Germany

for each class of age in Portugal with interest for lumbering. Eucalyptus and pine stand occur mainly in the north and center of Portugal. The other species stands occur mainly in south and inland of Portugal. The biomass distribution in Portugal was compared with the actual and planned location of the main intensive of industrial biomass consumers in Portugal (power plants, and co-generations plants) (Figure 5). Comparing the spatial distribution of Eucalyptus globulus and Pinus pinaster (Figure 6 (a), (d)) it seems that the existing and the predicted location for power plants is suitable, because they are near regions with high potential availability of biomass fuel. However, in relation to the other species considered as Quercus ilex, Quercus suber and Pinus pinea (Figure 6 (b), (c), (e)), their main areas of production are located in regions where no power plants implementation was planned.

i) – the spatial distribution of forest in Portugal by species of trees and respective age classes; ii) – the characteristics of stands of different species; iii) – the existing forest resources on the mainland. For tree species it was estimated the number of trees for the class of age with interest for lumbering, their spatial distribution in Portugal (using GIS tools) and the existed biomass forest residues (BFR) produced in result of sylviculture practices. The BFR amount was compared with the estimated amount of biomass to be consumed in existing and planned thermal power plants.

3

RESULTS AND DISCUSSION

To calculate BFR it was necessary to identify and classify forest cover, as well as to characterize forest stand structure in Portugal. 3.1 Number of tree species of Portuguese forest Based on typical sylviculture practices for each kind of species considered, namely the rotation periods for Eucalyptus and Pinus, and the maintenance cuttings of Quercus, was estimated the number of trees for the class of age with interest for lumbering. The number of Eucalyptus globulus aged between 8 and 12 years old was estimated in 66 million of trees. Pinus pinaster and Pinus pinea are both estimated in 17 million of tree, aged between 40 and 45 years old. For Quercus ilex and Quercus suber with around 9 years old were estimated around 680 thousand of trees (Figure 4).

Figure 4 – Number of trees based on IFN for the class of age with interest for lumbering. 3.2 Spatial distribution of forest biomass in Portugal After the number of trees for each class of age in Portugal was calculated, their spatial distribution was mapped using GIS tool (Figure 6). The spatial distribution of forested land cover was made at regional level, using so-called NUT II (Nomenclature of Territorial Units for Statistics) boundaries. The data provided by forest inventories [8] didn’t include the sample plot coordinates, and because no accurate map existed of forest land cover distribution using real data. In this way, the resultant map assuming that the forest biomass is uniformly distributed all over the region Figure 6 presents the distribution of the number of trees

Figure 5 - Distribution of existing and planned thermal power plants in Portugal [7].

537

19th European Biomass Conference and Exhibition, 6-10 June 2011, Berlin, Germany

Eucalyptus globulus

Quercus ilex

(a)

(b) Pinus pinaster

Quercus suber

(c) Pinus pinea

(d)

(e)

Figure 6 – Distribution of the number of trees for each class of age in Portugal. (a) Eucalyptus globulus (b) Quercus ilex (c) Quercus suber (d) Pinus pinaster (e) Pinus pinea.

538

19th European Biomass Conference and Exhibition, 6-10 June 2011, Berlin, Germany

3.3 Biomass Consumption in Portugal Actually there are nine thermal power plants and nine cogeneration plants in operation in Portugal corresponding to an installed capacity of 210MVA. There are thirteen thermal power plants planned corresponding to an installed capacity of 95 MVA.

Figure 7 presents the biomass consumption for existing and planned thermal power plants in Portugal. The existing thermal power plants need an estimated amount of 1,38x106 ton(dry)biomass/year, and the new thermal power plants will need an estimated amount of 6,89x105 ton(dry)biomass/year, that is, a total amount of 2,07x106 ton(dry)biomass/year.

Figure 7 - Biomass consumption for existing and planned thermal power plants in Portugal. Based on information about sylviculture practices and lumbering numeric models, it was estimated the following amounts of BFR for the five tree species considered (Tabel 1): i) 4.48×106 ton (dry)/year for Eucalyptus globulus, ii) 4.45×104 ton (dry)/year for both Pinus pinaster (4.38×104 ton (dry)/year) and Pinus pinea (6.82×102 ton (dry)/year), and iii) 1.21×104 ton (dry)/year for Quercus ilex and 1.35×104 ton (dry)/year for Quercus suber. The Figure 8 compares the biomass consumption for existing and planned thermal power plants in Portugal and the existing biomass from Portuguese forest.

3.4 The amounts of BFR in Portugal In order to obtain BFR estimations, the usual methods proposed in literature use different independent variables such as tree diameter at breast height (DBH), basal area, height, circumference or combinations of all of them. The most common procedure for estimating BFR in forest is to use allometric regression equations based on DBH and individual tree BFR [10]. The DBH is the most commonly used parameter because of the precision with it can be calculated and because it is related to the volume of the wood and the age of the tree [11].

Table I – Number of trees and the amount of biomass (kg (dry)) obtained for different species.

Specie

Equation(c)

mfinal DBH (cm)

T (years)

m (kg/tree)

Ntree (ton/year)

Eucalyptus

2.194

2.645DBH

2

12,5

(a)

10

(a)

674,6

66363629

4,48E+06

Pinus pinaster

0.4684DBH 6.3722DBH+36.698

21,1(a)

43(a)

110,8

16995737

4,38E+04

Pinus pinea

0.1129DBH2.4241

21,1(a)

43(a)

Quercus ilex

2.4727

(b)

Quercus suber

0.1006DBH

2.6079

0.0343DBH

46,2 28

(b)

183,2

160180

6,82E+02

9

(a)

1314,5

83178

1,21E+04

9

(a)

203,9

594839

1,35E+04

(a) Average value for sylviculture practices [12]. (b) Values obtained by statistical analysis of data from an experimental campaign [13]. (c) Equation for determinate the biomass for each species [14].

539

19th European Biomass Conference and Exhibition, 6-10 June 2011, Berlin, Germany

Figure 8 - Biomass consumption for existing and planned thermal power plants in Portugal and the existing biomass from Portuguese forest. [2]

The analyses of Figure 8 it is verified that the total consumption of both thermal power plants is 2,07x106 ton (dry)biomass/year and from Portuguese forest it’s possible obtain 4,55x106 ton(dry)biomass/year.

[3] [4]

4

CONCLUSIONS [5]

Considering that existing thermal power plants need an estimated amount of 1,38x106 ton(dry)biomass/year, and the new thermal power plants will need an estimated amount of 6,89x105 ton(dry)biomass/year, that is, a total amount of 2,07x106 ton(dry)biomass/year, it can be concluded that the existing residual forest biomass estimated from this five tree species (4,55x106 ton(dry)biomass/year) is enough to feed the existing and future thermal power plants. For the tree species considered it can be concluded that the major amount of existing biomass with potential for exploration is associated to Pinus pinaster and Eucalyptus globulus. However, only a part of this estimated amount could be made available forest biomass is accessible for lumbering, either in result of distances for forest production location to the industrial energy conversion installations and several logistic issues. Portugal has a high biomass potential which can be used in energy production, although it is already used by pulp and paper industries and furniture industries. Thus the use and probable competition for the same biomass resource requires special concern, to avoid the excess of exploitation, and consequent disequilibrium of ecosystems. The potential use of biomass for energy in Portugal has a tendency to increase, however we can’t forget that is necessary to invest in the management and sustainability of Portuguese forest.

[6]

[7]

[8]

[9]

[10]

[11]

[12]

[13] 5 [1]

REFERENCES Castro, R., Cordero, S. (2001). Tropical forest and the emerging CO2 market. Investigación Agraria: Sistemas Y Recursus Florestales; 1:185-204.

540

Zhang, X., Xu, D. (2003). Potential carbon sequestration in China’s forests. Environ Sci Policy; 6:421-32. REA – Relatório do Estado do Ambiente. (2009). Agência Portuguesa do Ambiente. EC – European Commission. (1997). Livro Branco: Energia para o futuro – fontes de energia renováveis, COM (97) 599 final. Comission of the European Communities. Communication from the Commission. Biomass action plan. COM(2005) 628 final. Brussels. 2005. DGGE. Estratégia Nacional para a Energia. A criação de uma rede de Centrais de Biomassa dedicadas. Direcção Geral de Geologia e Energia; 2006. AIFF. Relatório de Caracterização Florestal da Fileira Florestal 2010. Associação para a competitividade da indústria da dileira florestal; 2010. DGRF. Resultados do Inventário Nacional Florestal Nacional 2005/06. Planeamento e Estatística. Direcção Geral dos Recursos Florestais. Ministério da Agricultura do Desenvolvimento Rural e das Pescas. Lisboa; 2007. EEA – European Environment Agency. (2006). How much bioenergy can Europe produce without harming the environment?. EEA Report. 7. Rapp, M., Santa Regina, I., Rico, M., Gallego, H.A. (1999) Biomass, nutrient content, titterfall and nutrient return to the soil in Mediterranean oak forest. For Ecol Mang; 119:39-49. Satoo, T., Madgwichk, HAI. In: Nijfhoff, M, Junk, W, editors. Forest biomass. London: Forestry Sciences; 1982. Fernandes, P. (1998). Residual biomass in the Vale do Sousa region, Northern Portugal. Universidade de Trás-os-Montes e Alto Douro, Vila Real. Tomé, M., Amaral, J. P. (2006). Equações para estimação do volume e biomassa de duas espécies de carvalhos: Quercus suber e Quercus ilex. Departamento de Engenharia Florestal. Universidade Técnica de Lisboa – Instituto Superior de Agronomia.

19th European Biomass Conference and Exhibition, 6-10 June 2011, Berlin, Germany

[14] Montero G. Cuantificación de la biomasa forestal aérea y radical de distintas espécies arbóreas. In: Montes y energias renovables Ponencias y Comunicaciones Santiago de Compostela. Spain Asociación Forestal de Galicia; 2004.p.115-131.

6

ACKNOWLEDGEMENTS

The authors acknowledge to the Portuguese ‘Ministério da Ciência, da Tecnologia e do Ensino Superior’ for the financing of BIOGAIR project “Impacts of Biomass energetic recovery chain on air quality and Portuguese climatic policy” (PTDC/AACAMB/103866/2008)

541