Environmental Performance of Miscanthus, Switchgrass and Maize: Can C4 Perennials Increase the Sustainability of Biogas Production?

Kiesel, Andreas; Wagner, Moritz; Lewandowski, Iris

doi:10.3390/su9010005

Cited by 56 publications

(81 citation statements)

References 47 publications

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“…In general, the average MY for M×g found in our study (5,265 m³ CH 4 ha −1 a −1 ) is within the range found in other studies, namely 5,000–6,000 CH 4 ha −1 a −1 (Kiesel & Lewandowski, ; Kiesel et al., ; Mayer et al., ). This is at the lower end of the MY of maize (5,000–7,000 m³ CH 4 ha −1 a −1 ), as reported by Mayer et al.…”

Section: Discussionsupporting

confidence: 91%

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Harvest date and leaf:stem ratio determine methane hectare yield of miscanthus biomass

et al. 2018

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The suitability of miscanthus biomass for anaerobic digestion has already been confirmed by several studies. However, it is rarely used as feedstock in biogas plants, mainly due to uncertainty about the optimal harvest regime with regard to the long‐term methane hectare yield and resilience of the crop to green cutting. The recommended green‐cut date for the only commercially available genotype Miscanthus × giganteus (M×g) ranges from September to November. This timeframe is too broad for agricultural practice and needs to be both narrowed down and further specified for different genotypes. The aim of this study was to identify the most suitable harvest window for an autumn green cut of miscanthus, which delivers both a high dry matter and methane yield while securing the long‐term productivity of the crop. A further objective was to quantify the effect of genotypic differences, such as leaf to stem ratio, on the substrate‐specific biogas and methane yield. For these purposes, a field trial with four genotypes (M×g, GNT1, GNT3, Sin55) was conducted over 2 years (2016/2017) and harvested at 2‐week intervals on three dates between mid‐September to mid‐October. Methane hectare yield ranged from 3,183 m³ CH4 ha−1 a−1 (Sin55) to 5,265 m³ CH4 ha−1 a−1 (M×g), which is mainly influenced by dry matter yield. The substrate‐specific methane yield was higher for the leaf (311.0 ml CH4 (g oDM)‐1) than the stem fraction (285.1 ml CH4 (g oDM)‐1) in all genotypes due to lower lignin content of leaves. Of all genotypes, M×g showed the highest and Sin55 the lowest nutrient use efficiency. We conclude that miscanthus in Germany should be harvested in October to maximize methane yields and nutrient recycling and minimize yield reduction. Additionally, to increase methane hectare yields even further, future miscanthus breeding should focus on a higher leaf proportion.

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Section: Discussionsupporting

confidence: 91%

“…() and Kiesel et al. (). However, it should be noted that MY is mainly influenced by dry matter yield.…”

Section: Discussionmentioning

confidence: 98%

Harvest date and leaf:stem ratio determine methane hectare yield of miscanthus biomass

et al. 2018

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“…It was assumed that, after harvest, the biomass is transported over a distance of 5 km by tractor to the biogas plant. This transport distance is in line with other studies (Bacenetti, Fusi, Negri, Guidetti, & Fiala, ; Kiesel et al., ; Walla & Schneeberger, ). However, the use of marginal land for the cultivation of biogas crops could lead to higher transport distances in future (Liu et al., ).…”

Section: Methodssupporting

confidence: 92%

“…One example of biobased energy sources is biogas, which is produced by the anaerobic digestion of dedicated energy crops, manure or waste (Weiland, ). Various studies have shown that the production and subsequent combustion of biogas for heat and electricity generation has a significant carbon mitigation potential when substituting a fossil reference (Kiesel, Wagner, & Lewandowski, ; Lansche & Müller, ; Rehl, Lansche, & Müller, ). In 2016, over 18 million tonnes of GHGs were avoided through the use of biogas in Germany alone (FNR, ), with dedicated energy crops being the main input substrate.…”

Section: Introductionmentioning

confidence: 99%

Economic and environmental performance of miscanthus cultivated on marginal land for biogas production

et al. 2018

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Environmental issues surrounding conventional annual biogas crops have led to growing interest in alternative crops, such as miscanthus. In addition to the better environmental performance, miscanthus can be grown on marginal land where no competition with feed and food crops is anticipated. On marginal land however, biomass yields are significantly lower than on good agricultural land. This raises the question of the economic and environmental sustainability of miscanthus cultivated on marginal land for biogas production. This study assessed the environmental and economic performance of miscanthus cultivated on marginal land for biogas production by conducting a Life‐Cycle Assessment and complementary Life‐Cycle Cost analysis. The functional unit chosen was 1 GJ of electricity (GJel.). The substitution of a fossil reference was included using a system expansion approach. Electricity generated by the combustion of miscanthus‐based biogas in a combined heat and power has considerably lower impacts on the environment than the fossil reference in most of the categories assessed. In the impact category “climate change”, the substitution of the marginal German electricity mix leads to a carbon mitigation potential of 256 kg CO2e/GJel.. At 45.12 €/GJel., the costs of miscanthus‐based biogas generation and utilization are considerably lower than those of maize (61.30 €/GJel.). The results of this study clearly show that it can make economic and environmental sense to cultivate miscanthus on marginal land as a substrate for biogas production. The economic sustainability is however limited by the biomass yield. By contrast, there are no clear thresholds limiting the environmental performance. The decision needs to be made on a case‐by‐case basis depending on site‐specific conditions such as local biodiversity.

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“…(Wagner et al, ). In addition, Kiesel et al () compared the environmental performance of biogas produced using maize and miscanthus as substrate. They showed that the miscanthus‐based biogas production has significantly lower impacts on the environment in comparison with maize.…”

Section: Substratesmentioning

confidence: 99%

Status quo and perspectives of biogas production for energy and material utilization

Bahrs

Angenendt

2018

GCB Bioenergy

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Biogas is in many respects a serious alternative to other fossil resources and complements other renewable energy sources from wind and sun. Biogas can be produced in many places decentrally. Its energy potential is high, and it is widely used in the EU and all over the world. With more than 16,000 ktoe of oil equivalent in the EU in 2016, it corresponds to approximately 8% of the total primary energy produced by renewable energies in the EU, produced with nearly 17,000 biogas plants. Nevertheless, the production costs of biogas and its products like energy, heat, and fuel are still too high. Kost et al. (2018) show a comparison of electricity generation costs of different renewable energies and their future potentials. While electricity from huge biogas plants offers generation costs from 10 to 15 ct/kWh, electricity from onshore wind and huge solar systems offers generation costs from 4 to 8 ct/kWh. Although substantial progress has been made with regard to substrate use, production techniques and market designs, many more innovations are needed throughout the biogas value chain for it to be competitive in energy markets without high subsidies. As several papers in the special issue on biogas show, there are numerous innovations and product designs with regard to energy and material uses that could maintain or even increase the importance of biogas production both within and outside of the EU. There are many potential benefits of biogas, as it offers high shares of produced renewable energies as well as large amounts of material products like digestates and in future maybe products of higher value such as proteins or lactic acids.

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Environmental Performance of Miscanthus, Switchgrass and Maize: Can C4 Perennials Increase the Sustainability of Biogas Production?

Cited by 56 publications

References 47 publications

Harvest date and leaf:stem ratio determine methane hectare yield of miscanthus biomass

Harvest date and leaf:stem ratio determine methane hectare yield of miscanthus biomass

Economic and environmental performance of miscanthus cultivated on marginal land for biogas production

Status quo and perspectives of biogas production for energy and material utilization

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