Production of biomass and fuel use play a key role in assessing the climate benefits of bioenergy

Finland is one of the leading countries in the use of bioenergy in Europe. With the goal of reducing greenhouse gas emissions, use of fossil fuels and dependence on imported fuels, there is a wish to still increase the production and use of bioenergy. In addition, increased bioenergy is considered to provide employment and regional political benefits. Several objectives regarding bioenergy have been set both on the national and EU level. The life cycle chain of bioenergy has many environmental impacts. On the one hand, if compared to fossil fuels, biofuels reduce emissions, while on the other hand, they may increase the environmental burden.

Production of bioenergy

Bioenergy refers to energy received from biofuels. These, in turn, are fuels manufactured from biomass, i.e. organogenic plant material which has been created through photosynthesis and can be produced from farmland biomass and waste in addition to forest biomass. The majority of bioenergy is derived of wood and will most likely continue to be produced in forest industry plants. In Finland, energy use of farmland biomasses and municipal waste has been scarce, although use of the latter, in particular, is increasing. Reed canary grass and barley has been used to manufacture solid fuel for the use of power plants, thus creating electricity and heat as an end product [1].

Waste can be incinerated as such in waste-to-energy power plants, it can be mechanically manufactured into recovered fuel, or be further refined as biogas or liquid fuels, such as ethanol and diesel. Recovered fuel manufactured from waste refers to fuel manufactured from the combustible, dry and solid waste of communities and companies that is sorted at the creation sites. In addition, fuel created from unsorted municipal waste with a mechanical treatment and sorting process and recycled wood is considered recovered fuel. Mixed waste or recovered fuel does not create only bioenergy because it usually also includes plastic manufactured from fossil raw materials.

Manufacturing biofuels for traffic both from agricultural and forest biomasses and waste is subject of increasing interest.

Table 1 introduces the fuel types, basic technologies and materials used in bioenergy production as well as the side products produced.

Table 1.  Classification of bioenergy by fuels ([2] modified, original reference [3])

Fuel type

Basic technology

Raw material

Side products

Vegetable oils and animal fats

1) Used for traffic fuel either by changing the operation of the engines or by modifying the vegetable oils to be suitable for use in traditional engines

2) Production of electricity and/or heat

1) Rapeseed oil, sunflower oil and other vegetable oils, waste vegetable oil

2) Rapeseed oil, palm oil, jatropha oil and other vegetable oils, animal fat

Pressed vegetable reject used for feed

Biodiesel

Transesterification of oils and fats to produce fatty acid methyl esters (FAME)

Hydrogen treatment (Neste, NexBTL)

Used as traffic fuel

Rapeseed oil, sunflower oil, soybean oil, palm oil, jatropha oil

Pressed vegetable reject used for feed, glycerine, pressed reject of oil palm plants for incineration

Bioethanol

Fermentation (sugar), hydrolysis + fermentation (starch)

Used as traffic fuel

Grain, corn, sugar cane, cassava

Feed, plant reject for incineration

Biogas (CH4, CO2, H2)

Fermentation of biomass

Used either in a decentralised energy production system or supplied to a natural gas line (as cleaned biomethane)

Production of electricity and/or heat

Used as traffic fuel

Biodegradable waste (biowaste, sludges, manures), energy plants (corn, rapidly growing wood, plants with several crops)

Digest for fertilisation (recycling of nutrients)

Solid biofuels

1) Densification of biomass by torrefaction or carbonisation

2) Reject for the production of electricity and/or heat

Wood, grain, dry domestic waste, other biodegradable waste

 

Bioethanol

Decomposition of cellulolytic biomass in multiple phases, incl. hydrolysis and fermentation

Lignocellulosic biomass: straw of wheat, leaves and bones of corn, wood, energybearing plants (sugar cane)

 

Biodiesel and tailored biofuels (hydrogen, methanol, 2,5-dimethylfuran, dimethyl ether, alcohol compounds)

Gassing of biomasses that contain little moisture (less than 20%) produces syngas (CO, H2, CH4, hydrocarbons) that is used to manufacture liquid fuels and basic chemicals

Lignocellulosic biomass: wood, straw, secondary raw materials (plastic waste)

The Fischer–Tropsch synthesis can be used to produce chemical industry raw materials

Biodiesel, aviation fuels, bioethanol, biobutanol

Bioreactors for the manufacture of ethanol (can be combined with carbon dioxide recovery from power plants)

Transesterification and pyrolysis for the production of biodiesel and other technologies under development

Macro-algae in seas and micro-algae cultivated in ponds or bioreactors

Protein-rich feed, biopolymers, fertilisers

Use of bioenergy in Finland

In Finland, biofuels are primarily used in the combined production of electricity and heat, in which Finland is a leading country in the world. Instead, use of biofuels in traffic is scarce in Finland.

According to Statistics Finland, annual total consumption of energy in the 21st century has been 1,300–1,500 peta joules (PJ). With regard to biofuels, separate statistics are compiled on the use of wood fuels, and their share of the annual total consumption of energy has been approximately 20%. The majority of wood energy use is formed by forest industry waste liquors, bark, sawdust and wood residue chips. Use of these wastes in energy production is highly dependent on the production structure and volume of the forest industry [4].

Increasing the use of bioenergy

Several EU and national level strategies, clarifications and reports related to climate and energy policy suggest and demand that the use of bioenergy be increased from the current level. Both the use of biofuel in traffic and use of bioenergy for other purposes should be increased. In their promotion programme for renewable sources of energy [5], Asplund et. al. (2005) estimated the possibilities of achieving the goals set for 2010 and the visions set for 2015 from a technical and financial perspective. The following four bioenergy sources were estimated to have the greatest potential [6]:

• Increase in the use of forest chips (42 PJ)

• Increase in the small-scale use of wood (21 PJ) (excluding forest chips)

• Increase in the use of recovered fuel and biogas (21 PJ), of which recovered fuel add up to 14 PJ and biogas 7 PJ, and

• Increase in the use of farmland biomass (15 PJ)

The starting point for the estimate was the situation in 2003. Combined addition potential, 99 PJ, is approximately 7% of Finland's total energy consumption in 2005.

According to the estimate by the EEA [?] , Finland's greatest bioenergy potential is in waste which includes the waste liquors from the pulp and paper industry (table 2). Waste liquors are already utilised effectively in energy production and additional potential can only be created along with growth in pulp production. Additional potential can therefore mainly be found from the utilisation of agricultural and forestry energy products [7].

Table 2.  Bioenergy potential in Finland ([2] modified, original reference [?] )

 

2010

2020

2030

 

MtOE 1)

PJ

TWh

MtOE

PJ

TWh

MtOE

PJ

TWh

Agriculture

1.9

80

22

1.8

75

21

1.3

54

15

Forestry

1.7

71

20

1.8

75

21

1.8

75

21

Waste sector

6.1

255

71

6.2

260

72

6.2

260

72

Total

9.6

402

112

9.8

410

114

9.4

394

109

1) MtOE= Million tons of oil equivalent; the amount of energy that is released when a ton of raw oil is burned.

Environmental impacts of bioenergy

One of the most important factors supporting bioenergy is the reduction of greenhouse gas emissions. However, the life cycle chain of bioenergy has many environmental impacts. On the one hand, if compared to fossil fuels, biofuels reduce emissions, while on the other hand, they may increase loading. Some of the impacts are yet to be clarified. For example, biogas can be manufactured from many materials and the final environmental load depends on the raw material, whereas the environmental impacts of energy produced from cultivated crops depend on cultivation methods, among others. Eutrophicating and erosion causing impacts of direct seeding, for instance, are smaller than in ordinary cultivation [7].

The lifecycle environmental impacts of biofuels are formed mainly during the production of the biomass and use of the biofuel. Manufacturing phase of biofuel plays a less significant role and the environmental impacts of transports depend on the forms of transport. In most cases, even a long sea voyage in large transport units does not cause large-scale environmental effects per biofuel unit, but if the fuel is transported in smallish units by road, the impact of this phase with respect to climate change and other emissions in the air can become substantial [7].

Table 1 introduces first, second and third generation biofuels. Based on their operating characteristics or raw materials, biofuels can usually be divided into first and second generation biofuels. First generation biofuels refer to ethanol and biodiesel of cultivated crops origin whose use in current vehicles is subject to restrictions due to the operating characteristics of the fuels. Good-quality hydrocarbon fuels that are not subject to notable usage restrictions are considered second generation biofuels. Lignocellulosic materials, for example, can be used as raw material [7]. Classifications and definitions vary to some extent in different reports.

Bioenergy and sustainable energy production system

The most energy efficient way to produce bioenergy is to use wood material from forests, energy plants from fields and biowaste such as straw directly in combined production of heat and electricity. Logging residue chips, straw, smallwood and reed canary grass can be produced with less energy input than fossil fuels petrol and diesel[7].

In general, the energy efficiency of first generation traffic bio fuel manufacture is poor. Instead, manufacture of second generation biofuels is considered a much more promising possibility to produce biofuels energy efficiently. With regard to energy efficiency, biorefineries that do not produce biofuel alone seem promising [7].

In addition, with respect to costs, the most effective method to reduce greenhouse gas emissions is the use of wood-based biomass in combined production of heat and electricity if the created energy replaces coal, for example. In some cases, replacing peat with logging residue chips in the production of heat and electricity can even be profitable. If the straw can be utilised in the production of heat and electricity, grain-based ethanol can also achieve reasonable greenhouse gas emission reduction costs. However, if the energy in the straw is not utilised, grain ethanol and biodiesel manufactured in a traditional manner are not effective means to reduce greenhouse gas emissions. In the future, gassing of wood-based biomass (logging residue, black liquor, for example) in biorefineries integrated into forest industry could be one of the most cost-effective means to reduce greenhouse gas emissions when manufacturing biofuels suitable for traffic use [7].

In addition to climate change, energy efficiency and other environmental viewpoints, other dimensions of sustainability – economic and social sustainability – should be given consideration when assessing the life cycle chains of bioenergy. With the globalisation of economy, environmental protection will inseparably be connected to international responsibility for the sustainable use of natural resources. When assessing the production alternatives of biofuels, the alternative uses of the raw materials, such as food, chemicals and forest industry products, should be taken into account [7]

References

  1. Motiva 2009. Uusiutuva energia http://www.motiva.fi/toimialueet/uusiutuva_energia
  2. YM 2010. Biohajoavista jätteistä enemmän energiaa. Biojäte-energiatyöryhmän raportti. Ympäristöministeriön raportteja 3/2010. http://www.ymparisto.fi/download.asp?contentid=115599&lan=fi
  3. UNEP 2009: Towards sustainable production and use of resources: Assessing biofuels. http://www.unep.fr/scp/rpanel/pdf/Assessing_Biofuels_Full_Report.pdf
  4. Tilastokeskus 2010. Energian kokonaiskulutus väheni 6 prosenttia vuonna 2009. http://www.stat.fi/til/ehkh/2009/04/ehkh_2009_04_2010-03-24_tie_001.html
  5. Asplund, D., Korppi-Tommola, J. & Helynen, S. 2005. Uusiutuvan energian lisäysmahdollisuudet vuoteen 2015. VTT, Jyväskylän yliopisto ja Jyväskylä Science Park. http://julkaisurekisteri.ktm.fi/ktm_jur/ktmjur.nsf/all/E5063805F1B754D5C22570190028414D/$file/34642005.pdf
  6. EEA 2006: How much bioenergy can Europe produce without harming the environment? Report No 7/2006 http://www.eea.europa.eu/publications/eea_report_2006_7
  7. Antikainen, R., Tenhunen, J., Ilomäki, M., Mickwitz, P., Punttila, P., Puustinen, M., Seppälä, J. & Kauppi, L. 2007. Bioenergian uudet haasteet Suomessa ja niiden ympäristönäkökohdat. Nykytilakatsaus. Suomen ympäristökeskuksen raportteja 11/2007 http://www.ymparisto.fi/default.asp?contentid=240503

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