anaerobic digestion as biotechnology in agriculture … › eldo › 2018 › dl › 9788075981806...

INTERNATIONAL SCIENTIFIC DAYS 2018

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ANAEROBIC DIGESTION AS BIOTECHNOLOGY IN AGRICULTURE

FOR BIOMASS UTILIZATIONZuzana Kapustová1, Ján Lajda2, Jaroslav Kapusta3, Peter Bielik4,

Michal Levický5

Slovak University of Agriculture in Nitra1,2,3,4

Faculty of Management and Economics, Department of EconomicsTr. A. Hlinku 2Nitra, Slovakia

School of Economics and Management of Public Administration in Bratislava5

Karloveská ul. 64Bratislava, Slovakia

e-mail1, 2,3,4,5: [email protected], [email protected], [email protected], [email protected], [email protected]

AbstractProducing energy from biomass via anaerobic digestion (AD) has experienced a lot of attention in recent years. Biogas can be produced out of many different kinds of organic materials and its options for utilization can be equally versatile and can be used to generate electricity, heat, biofuels or digestate that can be utilized as a fertilizer.The amount of biogas produced can be increased by adding food waste to manure, however, maize silage is the most common input in EU and is 8 times more effective than cow manure in terms of biogas yield per tonne. The paper aims to summarize the main findings of the recent empirical studies related to biogas produced by biogas plants, discuss positive and negative externalities rising from producing energy via anaerobic digestion and give an overview about situation of biogas sector in EU.

Keywords: anaerobic digestion, bioenergy, biogas, externalities

JEL classification: L65, Q57

https://doi.org/10.15414/isd2018.s4.09

https://doi.org/10.15414/isd2018.s4.09

ANAEROBIC DIGESTION AS BIOTECHNOLOGY IN AGRICULTURE ...

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1 Introduction Producing energy from biomass via anaerobic digestion (AD) has experienced a lot of attention in recent years. Primary, the idea of the technology was waste management mainly in livestock production, waste of which represents an inten-sive agriculture’s externality. It seems to be a brilliant solution for two of the main EU`s issues – volatile business environment of farmers and limited conventional energy resources. Input substrate is renewable biomass waste from agriculture and the outcome is electric power, heat and microbes free fertilizer. Due to the high investments costs of biogas plant and low electricity prices, the whole con-cept is not economically viable and sustainable; therefore subsidy support system has been necessary in order to create a suitable environment for biogas industry growth.

“Anaerobic digestion is a microbial process that occurs in the absence of oxy-gen. In the process, a community of microbial species breaks down both complex and simple organic materials, ultimately producing methane and carbon diox-ide.” (Engler et al., 2013). European Biomass Association (2013) defines biogas as a secondary energy carrier that can be produced out of many different kinds of organic materials and its options for utilization can be equally versatile. Biogas can be used to generate electricity, heat and biofuels. Also the fermentation resi-dues, called digestate, can be used, for example as a fertilizer. Agricultural Tech-nical and Testing Institute (2013) describes biogas as a product of transformation of biomass into energy via an anaerobic digestion, where the resulting product is a biogas, serving as fuel for cogeneration units. Biogas reaches about 70% of the energy content of natural gas. Burning 1000 m3 of biogas can be obtained 2 178 kWh of electricity or 11.4 GJ of heat. Also, 1 m3 of biogas also contains as much energy as 0.6 to 0.7 dm3 of fuel oil for heating. Compared with conventional heat and electricity, up to 40% of fuel can be saved. Compressed and adjusted biogas can be supplied to the grid as natural gas. Only additional costs for treating biogas are the barrier, even though there are already developed technologies for such treatment (Holm-Nielsen et al., 2009).

Baxter (2014) points out that there are many ways how to realise flexible out-put produced by biogas plants. It is possible to store biogas with storage capacity locally and also via pipelines connecting more biogas plants. Excess capacity co-generation or combined heat and power (CHP) units might be used in times of deficit irregular renewable electricity generator or of the highest demand. There is a concept of many biogas plants linked together for flexible operation created already. Another alternative is to upgrade biogas to natural gas quality. Braun et al. (2015) believes that economic viability of the energy production from energy


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crops is possible only if we achieve high crop and biogas yields while keeping in-vestments, raw material and production costs low. What is more, other incentives are provided like subsidies and feed-in-tariffs to increase economics of the pro-cess. Then Gebrezgabher et al. (2010) underline that the financial viability of the system also depends on transport of input materials. Some researchers indicate that maximum economical distance is of 15–25 km. Logistics of inputs and out-puts are crucial indicator for biogas system to be economically, environmentally, and socially viable. Long distance transportation generates transportation cost as well as environmental costs in form of GHG emissions, odour and noise. There-fore these externalities of the transport should be managed to their minimums. Wellinger (2014) states that biogas plant operators will have to deal with secu-rity of sustainability of producing biomass and its higher yields per hectare via catch crop or multiple cropping on arable land. Other possibilities are permanent grasslands. There are also mechanical, physical and biochemical pre-treatment techniques to rice efficiency of biomass degradation. On the other hand Dollhofer (2014) reminds that these mechanical and chemical pre-treatment techniques come hand in hand with significant energy loses as they require high energy in-put.

The paper aims to summarize the main findings of the recent empirical stud-ies related to biogas production, discuss positive and negative externalities rising from producing energy via anaerobic digestion (AD) and give an overview about situation of biogas sector in EU.

2 Data and Methods The paper is based on both international and domestic publications addressing the issue of producing biogas by anaerobic digestion. Firtsly, the literature on the explanation of anaerobic digestion and its outcomes (biogas, digestate) is substan-tial. Several reports related to the effects of anaerobic digestion are taken into ac-count and positive and negative impacts on the environment, agricultural market and food production are discussed. The paper also points out the usage of food waste and manure for increasing the amout of biogas produced for creating ener-gy with no net carbon addition. The data presented in this paper are based mainly on the Biogas Report 2014-2017 of the European Biogas Association which were subject to mathematical and graphic processing. The data were analyzed by de-scriptive and quantitative techniques.


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3 Results and discussion3.1 Possitive and negative externalities rising from producing

energy via ADThe amount of biogas produced can be increased by adding food waste to ma-nure as many dairy farms do in the US (Renewable Waste Intelligence, 2013). It is because food waste fats, oils and greases are energy rich and produces more methane than bio solids. AD may be an interesting technology for food and beverage companies to manage a huge amount of organic waste they produce. Partnerships with local municipalities may create economically viable conditions for the technology and increase sustainability of the production and increase the corporate social and environmental responsibility.In the paper of Holm-Nielson et al. (2009), it is shown that there is a lot of animal manure produced in EU and anaerobic digestion of the manure for biogas production effectively cuts down ammonia, methane and other greenhouse gases from stored manure. Transform-ing manure into biogas via anaerobic digestion creates energy with no net carbon addition to the air and lowers danger from pathogens from land spreading as anaerobic digestion with sanitization procedure neutralize pathogens, added Ge-brezgabher et al. (2010).Furthermore, by-products from livestock industries like manure are considered as major reason of environmental pollution. Usually these products have been used directly or after composting process as soil supplements in agriculture. These practices have caused pollution of air, water and soil. The authorsemphasize that except biogas, anaerobic digestion produces also diges-tate, which contains a mixture of liquid and solid fractions. Applying digestate to land is the most useful way to let nutrients to be recovered and decrease soil degradation caused by agricultural exploitation.Several studies also indicate that anaerobic digestion organic waste origin can be the economical and sustainable solution for these issues. Zacharda (2013) stresses the fact that digestate from BGPs is an organic fertilizer comparable with manure or other kind of fertilizers which has been confirmed by positive results of research and experiments in the fertilization of agricultural crops. He confirms that processingbiomass as agricul-tural waste via anaerobic digestion is the most rational technology today. Using this technology substrates are exposed to specific temperature for long enough to eliminate pathogens and weed seeds, but the nutritional values retain in sub-strates. Moreover it decreases emissions that would be spilled into the atmos-phere and produces electricity and heat.Zegada-Lizarazu and Monti (2011) state that energy crops are less demanding for fertilizers and pesticides than traditional food crops and require lower level of intensive agricultural approach. With same production techniques like crop rotation, pest management and soil husbandry


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farmers can stabilize soil conditions and stabilize their income.Lovrence (2010) analyzed the biogas impact for society and farmers and found out that biogas pro-jects in form of BGPs may have positive influence from socio-economic point of view to each region regarding to rise of employment and investments depending on number of BGPs and their installed capacity. Additionaly, external economies are generated via biogas production and thus it affects consumer utility function (i.e. higher level of sanitary and hygienic conditions) and society’s social welfare function (i.e. decrease in health expenditures). At the national level, the biogas in-fluences energy balance by forming external economies via import of fossil fuels substitutes and diseconomies due to drop in import duties of fossil fuels which are substituted by biogas. Monopolistic effects on the electric energy market in many countries let energy suppliers ask higher than competition prices and leave biogas producers compete with distorted prices on the national and regional electrici-ty market. At the competitive market decentralized and economically viable and self-sufficient biogas plants push economy into its optimum. Another positive externality of decentralized energy producing facilities is increased power system security and energy security.

On the other hand,according to Vidal (2007), The United Nations highlights, that large scale energy crops production can significantly decrease biodiversity, cause erosion and nutrient leaching. There are thoughts that energy crops may be grown on the best lands and create an upward pressure on global food prices and increase also cost of emergency food aid. He sees another threat from energy crops production. Energy crops may not be beneficial for farmers either, as grow-ing energy crops can increase cost of cultivations and even cause that the poorest farmers will lose the most important production factor – land. New bio-economy attracts larger and larger companies into the rural areas which push out the local small farmers by controlling prices and owning the rest of the value chain.Ad-ditionally,Ogejo et al. (2009) suggested that facilities for anaerobic digestion are capital demanding and have operation costs. That may be the reason why it is not profitable and economically viable. Other problems may occur due to potential relies of gases, traffic movement, noise, and influence of the view and landscape. All the issues connected with anaerobic digestion can be, though worked out by right designed and well established management. Moreover, negative externalities are increasing investment costs due to additional networks costs, costs of loss-es and transmission costs (Lovrence (2010). Nevertheless, Lapcik and Lapcikova (2011) argue that most biogas plants do not have the negative effect on the land-scape in most cases because they are located often as a part of other agricultural or industrial buildings.


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3.2 Situation of biogas sector in EUAccording toEuropean Biomass Association (2013) usage of biomass as bioener-gy source will play the main part in achieving the ambitious goal leading to 20% of the final energy consumption to be produced by renewable sources by 2020, which is approved by the Renewable Energy Directive. Today biomass represents 2/3 of renewable energy sources in EU. Currently RES stands for of 8,5% of final energy consumption. Agricultural industry still poses a huge unutilized room in bioenergy sector believed to experience the highest growth in near future (Eu-ropean Environmental Agency 2, 2006). Even if today forestry is main supplier of biomass used for biogas, according to European Biomass Association (2013), agricultural sector is believed to be the most important source of energy already by 2020. In 2007 share of biogas out of total bioenergy was about 7% but the potential of biomass is at level of 15%-25%. There however is need for actions at local, regional, national and international level. Today it is the maize being nomi-nated as an energy crop for biogas production. There is a wide room for use of by products and wastes from food industry and household waste for energetic use too. There is high possibility that main input for biogas will be animal manure. Today about 50 PJ of energy is produced from energy crops, organic waste and animal manure whereas there is the potential to produce 827PJ solely from ani-mal manure in the EU (Birkmose et al., 2007).

It is necessary to promote usage of biogas plants and therefore the most com-mon and also very efficient tool to enhance the technology of anaerobic digestion are subsidising the sale of electricity produced in biogas plants (Birkmose et al., 2007).Favourable conditions like feed-in-tariffs were created in many states of EU for energy produced from biogas (European Biomass Association, 2013). Accord-ing to Wellinger (2014), European feed-in-tariffs support system electricity from biogas in agriculture created a successful story. Also the EU legislation managed to treat biowaste through anaerobic digestion rather than open landfilling. There are over 4000 BGPs in Germany, mostly on farms with cogeneration unit that makes Germany the leader in this field.

European Biomass Association (2013) describes different situation across Eu-rope as while in countries like Germany, Austria and Denmark BGPs are used to produce biogas from agricultural commodities and by-products, in UK, Italy, France and Spain, they use landfill gas. This kind of utilization is not expected to have higher growth in future because the EU directive on landfill waste foresees a gradual reduction of the land filling of biodegradable municipal waste. On the other hand, Monbiot (2014) highlights the increasing trend of anaerobic diges-tion in the UK and warns that there is a similarity with another genius idea be-hind turning waste chip fat into biodiesel which turned rainforests in Indonesia,


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Malaysia and West Africa into oil palm plantations and has a lot higher green-house footprint than fossil fuels it replaces. Further, he explains that the prob-lem is that yields of gas from waste and slurry from cattle and pigs are not high enough to make conversion of wastes economically viable. Searby (2014) refers to Dr. David Styles from Bangor University, UK sees the issue is in high capital investments of AD and the small size of dairy farms so AD technology is not economically viable and that is the reason why the most used input for AD is purposely grown crops. Maize has higher biogas yield per tonne than food waste or slurry so it increases income from subsidies per m3 AD unit capital invest-ment. Monbiot (2014) agrees that the most suitable commodity is maize which has become the biogas core crop as it has high yield per hectare and also high yield of biogas per tonne and According to National Farmers Union (NFU) there will be 100 – 125 thousands of hectares used for maize alone in the UK if 1000 medium-sized biogas plant using maize along with slurry and manure are built by 2020. In addition, Searby (2014) shows that animal feed supply might get under a pressure due to increase use of anaerobic digestion technology in the UK. Then he explains that processing fodder crops with anaerobic digestion instead of feed-ing livestock may lead into lack of feed produced in the country and its import will be needed. Further causes may be forest and grasslands turned into fields for other agricultural commodities production. Most of the people do not know that we already have cars running on natural gas for many years now and biomethane might be one of the key power sources in transportation sector. By now, there is only one market for vehicles using biomethane as fuel in Sweden. Thanks to the low prices of electricity, only about 8% is used for electricity, 50% of biogas is used for heating and roughly 25% is upgraded and used in transportation in Sweden (European Biomass Association, 2013).

Bruns et. al. (2009) remind that at the end of the year 2007 started the discus-sion about national and global effects of bioenergy. The sector was criticized for competition between production of inputs for bioenergy and food production. On the other hand, Zeller et al. (2009) state that most of the regions in Germa-ny have enough feedstock to fulfil needs for both food and biofuel production. Food crops such as wheat and rye are usually used as food crops. Mostly food and energy crops as well are traded on an interregional basis and exported to other countries of the EU, according to which there is no competition between food and energy crops. Bruns et al. (2009) further state that reported environmental and social impacts of bioenergy caused that it lost its positive credit in public. Further it has become obvious that bioenergy had not outrun other forms of renewa-ble energy sources. Even if biogas turned into electric energy is more efficient in terms of yields per hectare and production of CO2 than biofuels, the decreased


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public confidence influenced significantly biogas sector also because there was no public distinction between biofuel and biogas within bioenergy. One of the key weaknesses was lack of heat utilization.

European Biomass Association (2013) believes that usage of energy crops for energy will climb in next 10-20 years and is expected that 10-20 or 30 % of the arable land will gradually move from food and feed production to energy farm-ing. Large European countries like France or Ukraine that have fertile soils may become leaders in bioenergy industry. Importance of crops like maize, sugar beet and others will rise in Europe. An ambitious target of biogas is to replace fossil fu-els in electricity, heating and biofuels sector in the whole continent. What is going on in Germany is symptomatic for other countries and that is why it is necessary to ensure continuous growth of the biogas energy as a clean and sustainable ener-gy source. The new target for European Biogas Association is to ensure that 1,5% share of primary energy in the EU will be biogas based by 2020 (conBio, 2014).

The development of biogas plants in Europe has experienced positive trend since 2009 (Figure 1). There was an increase of the total number of biogas plants experineced from 6 227 to 17 662 installations (+11 435 units). The increase in the number of plants in 2010 compared to the number of plants in 2009 was the greatest with 4 281 new plants which represent an increase of 69%. Significant changes which occurred in different parts of Europe, mainly changes in support schemes caused a slow down in 2013 when a number of plants rose only by 6% in comparison to the previous year. Torijjos (2016) gave an example of the situation in Germany where the number of plants was increasing by more than thousand a year in the period 2009-2011, but after the Renewable Energy Act EEG 2012, the German market was dramatically slowed down and the increase in the number of plants in 2013 was only 335. According to European Biogas Association (2017), most of the growth derives from the increase in plants running on agricultural substrates: these went from 4,797 units in 2009 to 12,496 installations in 2016 (+7,699 units, 67% of the total increase). Agricultural plants are then followed by biogas plants running on sewage sludge (2,838 plants), landfill waste (1,604 units) and various other types of waste (688 plants).


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Figure 1 Evaluation of the number of biogas plants in Europe

Source: authors´ processing, European Biogas Association (2017)

Figure 2 Biogas plants in Europe in 2015


The installed electric capacity experience upward trend during the period 2010-2016 (Figure 3). In 2016, the installed electric capacity rose by 5 827 MW, reaching a value of 9 985 MW, comparing to 2010 (4 158 MW). The significant increase was recorded in 2012 when the installed electric capacity grew by 2 487 MW (+52%). The installed electric capacity rose by 9% in 2016, compared to the previous year. European Biogas Association (2017) explains that growth in in-stalled electric capacity since 2011 has been mainly due to the building of plants running on agricultural substrates: such plants went from 3,408 MW in 2011 to 6,348 MW in 2016 (+2,940 MW – 56.5% of the total increase).


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Figure 3 Growth in installed electric capacity in Europe


There was a rapid increase recorded in the development of biomethane pro-duction since 2011 (Figure 4). The production rose from 752 GWh in 2011 to 17 262 GWh, representing growth by 16 512 GWh in 2016. The rapid growth was experienced in 2013 when biomethan production went up by 308% in compari-son to 2012. The countries which saw the most significant development in biom-ethane production in 2016 were Germany (+900 GWh), France (+133 GWh) and Sweden (+78 GWh).

Figure 4 Evolution of biomethane production in Europe


Conclusion Biogas can be produced out of many different kinds of organic materials and its options for utilization can be equally versatile and can be used to generate elec-tricity, heat, biofuels or digestate that can be utilized as a fertilizer.This paper pre-sented the overview of the recent empirical studies related to producing energy via anaerobic digestion, dealt with its effects on the environment and agriculture and discuss the situation of the biogas sector in EU. It also discussed the issue of transforming manure into biogas via anaerobic digestion as a suitable alternative


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input material instead of e.g. maize that is mostly grown on arable areas of EU and thus leads to the fact that agricultural biogas stations have a negative impact on the landscape (environmental defects on soil, water and biodiversity), increase in land rent, and afterwards massive maize production causes decrease of food crops production and afterward rise in food prices. Therefore, it is essenntial to en-sure that producing bioenergy via anaerobic digestion representing secure, clean and efficient energy will be performed by sustainable way and by elimination of negative effects on environment and agriculture e.g. AD may be an interesting technology for food and beverage companies to manage a huge amount of organic waste they produce.

AcknowledgementsThis work was supported by AgroBioTech Research Centre built in accordance with the project Building „AgroBioTech" Research Centre ITMS 26220220180.

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