Wood Waste Management in Europe through the Lens of the Circular Bioeconomy

Abstract

Over 30% of the world’s land area is covered by forests. Approximately 761 million m³ of wood is harvested annually in Europe (2017). The aim of the paper is to assess the amount of wood (biomass) produced in Europe per year, as it determines the amount of carbon dioxide released from wood because of combustion for heating and energy purposes. The circular bioeconomy was applied as the theoretical framework for this study. The study employs official statistics on material flows and also uses a technology assessment, which allows for more precise estimations. It can be estimated that 110 million tons of harvested woody biomass are converted into energy every year. This constitutes nearly 69% of processed wood, with burned wood treated as zero-emission. From the analysis of the compiled results, it can be concluded that, in Europe, more than 50% of the mass of raw wood material harvested per year is used for energy in the first stage of processing by manufacturing industries. These processes produce products that become the raw material for further processing, as a result of which, further amounts of wood biomass are used for energy purposes.

1. Introduction

Wood has always been and still is of great importance to mankind. Its properties and impact on the natural environment, as well as its contribution to the economy and society, are summarized in Figure 1.

The forest area of EU-27 was estimated at 159 million hectares as of 2020, which increased from 1990 by 10% [1]. The total roundwood production of EU-27 in 2018 was estimated at 489.8 million cubic meters, which was a 5.5% increase from the previous year, and a whopping 21.2% gain from the year 2000. Forests are natural elements of rural landscapes and forestry measures are integral parts of rural development policies [2]. The European Green Deal mentions designing deeply transformative policies, referring to forest ecosystems [3]. Some countries, e.g., Finland, with extensive forest cover and a long history of forestry display ambitions to be a forerunner in the new global bioeconomy rooted in this sector [4].

The EPF Annual Report [5] provides a schematic assessment of the flow of raw wood material in Europe, leading us to the conclusion that from the 160 million tons of processed wood used per year, only 20 million tons remain in used products for a period of longer exploitation. This constitutes only 12.5% of the initial mass. Thus, around 10 million tons of carbon are bound in wood in Europe every year. It can be estimated that 110 million tons of harvested woody biomass are converted into energy. This constitutes nearly 69%, with burned wood treated as zero-emission. Although burned wood releases CO₂ during combustion, similar to most fuels, this carbon dioxide is treated as relatively recently bound by nature in the vegetation process. It is in a continuous normal cycle of CO₂ circulation in nature. At the same time, consumer products, i.e., products of the wood manufacturing industry, before their further processing and use, constitute 50% of the total output biomass. The purpose of this study is to check and possibly specify this value for Europe and Poland, as well as the values associated with it.

Basic classifications of bioeconomy activities can be described, as these directly exploit bioresources. Primary activities include agriculture, fishery and forestry. Secondary activities include food or wood processing plants. Finally, tertiary activities include converting biowaste or by-products into energy or chemical compounds, as defined by [6], or similarly by [7]. Wood-related activities can in fact be placed within all these three groups.

We apply a circular bioeconomy as a theoretical framework for this study. The theoretical foundation of the circular economy is based on the concept of material cycles [8], concentrating on reusing, regenerating, renewing, repairing, cascading and modernizing products, components and materials. Circular bioeconomy also focuses on the role and potential of renewable energy sources, such as biomass and waste energy. Its implementation can have positive results for environmental growth and economic development [9,10,11]). Some authors display an even usage of waste/by-products as the key to a sustainable and circular bioeconomy [6]. For example, waste biorefineries are pointed out as an instrumental tool to achieve the vision of a circular bioeconomy [12].

Woody biomass is a source of energy during different stages of biomass flow. It occurs right at the beginning of the process as well as at the end, whereas applications for energy purposes should take place at the end stages, as postulated by the circular bioeconomy principles [13]. The conversion of biomass to biological products and biofuels provides a sustainable way to manage degradable biowaste. However, some studies indicate the term ‘circular economy’ (CE) as already referring to the fusion of the circular economy and bioeconomy agendas, with varying degrees of emphasis on bioproducts and bioenergy [14]. The application of this concept to wood-related activities is not new [15,16,17,18,19], as wood is a key source of biomass. Together with agriculture and aquaculture, the forest sector plays a key role in the transition to circular bioeconomy. Additionally, circular economy in the wood and furniture sector is part of the international curricula for higher education [20]. However, according to a review of the analysis by Boloy et al. [21], research on waste-to-energy technologies towards circular economy is apparent in some European Union Countries (e.g., Italy, Germany) and for other countries worldwide (e.g., USA, China, India), but those in Poland are not so numerous [22].

The aim of the paper is to assess the amount of wood (biomass) produced in Europe per year, as it determines the amount of carbon dioxide released from wood because of combustion for heating and energy purposes. The important feature of this study is that it employs not only official statistics but also a technology assessment [23] which allows for more precise estimations.

2. Materials and Methods

The analysis in this work covers the area of the European continent. It should be clarified that all harvested and processed wood in Russia was included, although geographically, the European part of this country’s territory accounts for only 25% of its total land territory. It would be very difficult to separate wood harvested in Russia from Europe and Asia. That is why almost all sources locate Russia in Europe, together with all minerals and wood obtained in this country. FAO statistics also include wood harvested and processed in Russia in European statistics.

In the management of raw wood material, it is very important to answer the following questions: how much wood harvested remains in finished products manufactured by individual industries for which it is a raw material, and how much is post-production waste? In many cases, this waste can be a valuable secondary raw material for other industries.

Where wood processing is dispersed, thousands of different products are produced, and this process takes place in thousands of small businesses where statistical data are missing or are very approximate. Therefore, it should be assumed that this study will, in many cases, involve the need to accept approximate data, and even presumptive data.

Wood as a material is very diverse. There are many species of wood, and the division into coniferous and deciduous also roughly groups various material characteristics. Therefore, for the purposes of this study, the term “SWE” (solid wood equivalent) will be used. It was adopted based on the annual report of 2018/19 of the European Panel Federation, which has been dealing with the issue of using wood for production and energy purposes on a broad scale for many years, not only for wood-based panels. The adoption of such a unit, from the moment of harvesting wood in the forest to the final balance, showing how much of it remains in the products and how much of it returns to circulation in nature through combustion or composting, is convenient for many reasons.

Speaking about the amount of biomass that Europe has at its disposal every year, it should be emphasized that different sources define this mass in different ways [24]. The global bioeconomy plans to place a premium on the sustainable management of organic resources to ensure asset viability and biomass sustainability [14]. It is assumed that, for long-term analysis, the source of biomass is not only forest wood obtained in a given period, but also post-production biomass from industry, which is its buffer, as well as biomass from post-consumer (recycled) wood and biomass from unidentified sources. That means post-production biomass is formed as a result of the further processing of forest timber obtained earlier, as well as previously produced timber and boards. Following this reasoning, one can conclude that, as a result of processing a given amount of wood in a given time period, there are wood products created that supplement the buffer.

Biomass can be used to produce a specific product, but also to generate energy, e.g., for production processes. Wood products, including by-products that meet the requirements of PN-EN ISO 17225-1, are treated directly as biofuels. Wood waste that can be used as fuel (burned) by natural persons or organizational units that are not entrepreneurs, usually in low-power heating devices, overlap with category AI of the German regulation “Altholzverordnung” (natural wood waste or only mechanically processed wood which has been slightly contaminated with non-wood-related materials). Due to the fact that this biomass waste can be burned in household appliances and similar low power devices, the fuel burned in them must be of high quality and cleanliness. For the same reason, stringent quality standards are set for manufacturers of wood pellets intended for non-industrial use (domestic and in low-power heating installations).

Unfortunately, the resulting amount of wood consumed by the industry in Poland in 2017 does not match the actual consumption recorded by Statistics Poland and FAO statistics. For the sake of this research, the calculations for Europe and Poland were based on FAO statistics and the data from Statistics Poland should be treated as comparative. According to FAO statistics, the industry consumed 38 887 thousand m³ of wood, rather than 33 783.3 thousand m³. The wood consumption of pulp and paper factories and wood-based panels have been calculated in detail and should be taken as genuine. The remaining amount of wood is consumed by the sawmill industry, with the inclusion of well-developed Polish branches producing pallets and garden programs. In addition, in Poland, there is a very large number of small family sawmills not present in the statistics. In 2017, Poland’s pallet industry, garden industry, and other wood industries consumed just over 5 million m³ of raw round wood material. One must consider here how much processed wood in this expanded primary processing industry goes to finished products, and what are by-products, i.e., post-production wood.

Regardless of the wood balances above, in Poland, as well as in Europe, wood is obtained from unidentified sources. It is mostly firewood, obtained from cutting trees in home gardens, roadside trees, orchards and allotments. It is difficult to estimate the amount of this wood that is used for energy as fuel in households. In order to include wood from unidentified sources, it was assumed that the weight in Poland was proportional to the weight in Europe for the EU-28.

3. Results

We considered the processing of wood in Europe in 2017 from three basic industries:

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The sawmill industry;

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The wood-based panel industry;

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The pulp and paper industry.

Thus, we concluded that, in order to produce the quantities of products shown in the FAO statistics, it was necessary to use a certain amount of raw wood material, as summarized in

Table 1. Summary of the amount of raw material consumed by the woodworking industries in 2017 in Europe.

No.	Type of Raw Material (Thous. m3 SWE)	Sawmill Industry	Wood-Based Panels	Pulp and Paper	Total
1.	Forest wood (thous. m3)	330,368.7	105,156.5	152,577.0	588,102.2
2.	Post-prod. wood (thous. m3)	0.0	40,711.0	46,273.0	86,984.0
3.	Recycled wood (thous. m3)	0.0	25,076.5	0.0	25,076.5
4.	Total raw wood material (thous. m3)	330,368.7	170,944.0	198,850.0	700,162.7
5.	Produced post-production wood (thous. m3)	172,113.0	41,466.8	91,168.0	304,747.8
6.	Prod. energy wood (thous. m3)	0.0	36,778.9	0.0	36,778.9
7.	Products (million. m3)	163.5	129.4	107.7 (million. t)

Source: based on production indicated in the FAO Forest Products 2017 statistics.

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On the basis of the data compiled in Table 1 and after the consolidation of the raw material flow for the considered basic wood processing industries in Europe, a Sankey chart (Figure 2) for 2017 was made.

Additional calculations were made to create the chart:

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The amount of wood remaining to be used in Europe in 2017 consisted of harvested wood, was reduced by the balance resulting from the excess of export over imports, and was increased by wood from unidentified sources (Equation (1)).

(760665.0 − 14897.0 + 136210.0) thous. m³ = 881978.0 thous. m³ =≈ 882.0 million m³

(1)

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From the mass of 882 million m³, only 588,102.2 thousand m³ was used by the industry. At the stage of preliminary energy distribution, forest firewood comprised 156,956.0 thous. m³ and surplus (Equation (2)):

(881978.0 − 588102.2 − 156.956) thous. m³ = 136919.8 thous. m³ =≈ 137.0 million m³

(2)

In other words, in the initial division, this amount of energy was already managed:

157.0 million m³ + 137.0 million m³ = 294.0 million m³

(3)

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Post-production wood consisted of three sources coming from three industries: sawmill, wood-based panels, and cellulose and paper. The amount of this wood was calculated as follows (Equation (4)):

(166836.2 + 41466.8 + 91168.0) thous. m³ = 304747.8 thous. m³ =≈ 299.5 million m³

(4)

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Of this amount of post-production wood, less than 30% is industrially used in the pulp and paper industry (46.3 million m³) and in the wood-based panel industry (40.7 million m³). The rest of it is used for energy either directly for production purposes or in other energy-generating plants. Therefore, post-production wood amount for energy use is calculated by (Equation (5)):

(299.5 − 46.3 − 40.7) million m³ = 212.5 million m³

(5)

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In 2017, 18,402 thousand tons of pellets were produced in Europe. The pellet on the graph is a branch from the energy wood field that returns to this field, as this product is for energy use only. To convert this product into SWE units, it was simplified with pine wood with a specific weight of one m³ of green wood mass after drying 448 kg (Equation (6)):

18402000 t: 0.448 kg/SWE = 41075.9 thous. m³ SWE ≈ 41.1 million m³ SWE

(6)

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Ultimately, the energy wood field consists of the above-calculated part of post-production wood (217.8 million m³), firewood with primary distribution (294.0 million m³), and the energy part of recycled wood from the wood-based panel industry (36.8 million m³) (Equation (7)).

(212.5 + 294.0 + 36.8) million m³ ≈ 543.3 million m³

(7)

Analyzing the diagram presented in Figure 2, it can be concluded that, in 2017, the European economy had biomass from the following sources in quantities of biomass expressed in m³ SWE of solid wood equivalent, as presented in

Table 2. Raw wood material distribution in Europe in 2017.

Specification	Million m3
Forest wood	760.7
Wood from unidentified sources	136.0
Wood resulting from the export–import balance	−15.0
Post-consumer wood (raw m. in wood panel ind.)	25.1
Post-consumer energy wood (wood panel ind.)	36.8
Total	943.6
Amount for energy purposes used
in the wood-based industry (post-consumer)	36.8
In the economy	506.5
Total	543.3

Source: own based on the Figure 2.

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The amount of biomass used for energy is therefore 57.6%, compared with the amount available in the economy in 2017. However, if the mass used for energy relates to fresh forest wood harvested in the analyzed year, i.e., 881.7 million m³, we will receive 61.6%.

The share of basic industries in the consumption of forest wood resulting from the diagram presented was also interesting. This quantity in m³ SWE was used as follows:

- Sawmill industry	- 330.4 million m3 (37.5%);
- Sawmill industry	- 152.6 million m3 (11.9%);
- Wood-based panel industry	- 105.2 million m3 (17.3%);
- Energetics	- 294.0 million m3 (33.3%)

4. Discussion

According to the research of Lazaridou et al. [25] publications on forest-based circular economy refer to extremely wide subjects, and are addressed especially in countries of high wood production, for instance, Malaysia [26]. Compiling the results of other authors, they conclude on the interactive relationship between circular economy and the environment. Forest system services benefit from this relation in different ways: the demand on natural resources is reduced and suitable management approaches to improve the nutritional state of forests are employed.

The results of this work are summarized in

Table 3. Primary division and wood processing: summary of results.

	All Europe 2017	Poland 2017 Version “a”	Poland 2017 Version “b”
Total wood biomass (million m3) SWE	943.6	54.3	54.3
Raw material sawmill industry (million m3) SWE	330.4	21.5	21.5
Raw material pulp and paper ind. (million m3) SWE	198.9	5.8	5.8
Raw material wood-based b. ind. (million m3) SWE	171.0	19.7	19.7
Energy (million m3) SWE	543.3	23.0	25.6
% energy use to total mass	57.6	43.8	47.1
% energy use to forest wood	61.6	45.0	48.4

Source: own based on own calculations and [23].

. They concern Europe for the EU-28 in 2015, and the entire European continent in 2017. Data for Poland include versions “a” and “b” of calculations for the sawmill industry in 2017 (“a” assuming 65% wood output performance indicator and ”b” assuming 48%). From the analysis of the compiled results, it can be concluded that, in Europe, more than 50% of the mass of raw wood material harvested in the year is used for energy in the first stage of processing by manufacturing industries. These processes produce products that become the raw material for further processing, resulting in further amounts of wood biomass being used for energy purposes. For example, a case involving the Italian Valdarno–Valdisieve forest-wood supply chain shows that if all wood residue produced were allocated to energy production in local HDPs, this production would satisfy 53% of the total energy demand. Instead, currently only 38.3% of total energy demand is satisfied by local wood residue [27]. It is possible to find discussions and analyses on the use of wood residues to generate bioenergy for the self-sufficiency of local communities in Mexico in various studies [28].

A well-planned production process can provide more proficient production by reducing the amount of waste. The proper management of raw materials leads to savings and reduced production costs [29]. The comparison shows that, in Poland, in the first stage of wood processing, more than 10% less raw material goes to energy use. This is a favorable phenomenon. The reason is the use, especially in smaller sawmills, of better material handling when sawing. This, of course, is associated with greater labor consumption. However, the 65% adoption of the material utilization factor for sawing differs fundamentally from the 49.5% adoption in Europe. In Poland, most sawmills produce and use waste wood (slabs rounded on one side of a plank and made from sawing barked log), which in large sawmills are turned into chips. This waste wood is still traditionally used on farms. In addition, Poland is one of the European leaders in the production of wood-based panels. It occupies second place in Europe in this field. The production of panels uses a relatively large mass of post-production wood. If wood cannot be used in such a way, it goes directly to the boiler, or is indirectly used after processing in briquettes or pellets.

This work can be used in various ways to improve the rational management of raw wood material both in Poland and, more broadly, in EU countries. It is important to note that over 61% of harvested timber is burned in Europe every year. This wood is a natural storage of carbon dioxide, a greenhouse gas. Better use of timber provides mass that, for the period of its use, creates a natural buffer for this gas. One can easily notice a relatively high rate of raw material utilization occurs in construction, by means of sawn timber and wood-based panels. Particularly in Poland, wooden constructions are irregularly propagated and used. This study can be a source of information and argument when promoting wood-based construction. Work towards better documentation of the mass of timber harvested every year should be continued and made more specific. However, it should be also mentioned that the scope of the current study is not able to cover all emerging issues connected with wood waste management or wider topics of bioenergy production based on wood. It is necessary to develop further studies involving, for instance, the significant issues of soil CO₂ sequestration and land use, which make important trade-offs. It cannot be forgotten that bioenergy has the highest impact on ecosystem quality, and is a measure of deforestation, ecosystem restoration, and biodiversity [30].