Views
5 years ago

BIOENERGY FOR EUROPE: WHICH ONES FIT BEST?

BIOENERGY FOR EUROPE: WHICH ONES FIT BEST?

68 4 Environmental

68 4 Environmental results: presentation, discussion and interpretation large. Regarding acidification, and eutrophication, the negative “side-effects” of the biofuels are smaller in comparison. For acidification, again firewood as well as triticale exhibit slight advantages over the fossil fuel (although these do not appear significant, but the results can at least be regarded as “neutral”), while all other biofuels have negative impacts in this category, particularly biogas and RME. Regarding eutrophication, only SME shows an advantage over its fossil equivalent (diesel fuel). With respect to summer smog, apart from wheat straw, firewood and Miscanthus the biofuels show slight advantages over the fossil fuels. A further assessment in favour of or against one of the biofuels cannot be carried out on a scientific basis, because for this purpose subjective value judgements regarding the individual environmental categories are required which differ from person to person. 4.4 Summary of country specific results In this chapter, the results of the life cycle comparisons between biofuels and fossil fuels in each participating country are summarised and described. The full results are given in the Annex (Chapter 7.1) to which the interested reader is referred for details. Regarding an overall picture of the biofuels in the various countries, the main conclusions are generally similar to those for the European results, i. e. that the biofuels are advantageous with regard to the parameters use of fossil fuels and greenhouse effect, but the fossil fuels have, by and large, greater advantages with respect to the other parameters. It should be noted that the representatives of each participating countries were fully responsible for the results presented in Chapter 7.1 as well as the following summaries, including the form of presentation and interpretation. Therefore the structure of these presentations differs from country to country.

4.4 Summary of country specific results 69 4.4.1 Austria Austria investigated Triticale for electricity, firewood and wheat straw for heat, rape seed oil methyl for transport fuel and biogas for combined heat and electricity. For the evaluation the Austrian Energy Policy, the “White Paper” of the Commission, the Kyoto Goals and the UN/ECE Convention on Air Pollution were used. N2O and photo-oxidants were considered on a scientific level. Triticale for the electricity production compared with hard coal displays major advantages concerning the use of fossil energy and greenhouse gas emissions. The effects on acidification and on summer smog are positive but minimal, no changes could be observed in the category human toxicity. Deterioration is observed by N2O and eutrophication, but the absolute increase is rather small. Traditional firewood compared with light oil and natural gas for heat production shows major advantages concerning fossil energy and greenhouse gases. Regarding acidification, eutrophication, summer smog and human toxicity the differences are small. The substitution of oil shows better results in greenhouse gases and in acidification, the substitution of gas reduces summer smog. Wheat straw compared with light oil and natural gas for heat production displays major advantages concerning fossil energy and greenhouse gases. The differences regarding acidification, eutrophication, summer smog and human toxicity are small. If straw substitutes oil the emissions of greenhouse gases and acidification are improved considerably, the substitution of gas will reduce summer smog. Rape seed oil methyl ester compared with fossil diesel for transportation shows advantages concerning fossil energy and greenhouse gases. The effects on eutrophication, summer smog and human toxicity are positive but minimal. Considerable increase is observed in N2O-emissions and acidification. The absolute change in acidification is rather insignificant but the N2O burden increases significantly. Biogas from swine excrements compared with natural gas for heat and electricity shows advantages concerning fossil energy and clear advantages concerning greenhouse gases. The effects on acidification, eutrophication, summer smog, N2O and human toxicity are minimal. For an overall comparison the different levels of development, different types of useful energy, the different states of the technology and the different costs must be considered. The following table compares the chains only on the basis of fossil fuel saving and availability of land (based on a mix of bioenergy we have estimated a possible increase of 50 to 80 PJ until 2010 under a committed policy for Austria, the evaluation in the following table refers to a reduction of 20 PJ fossil energy per chain). Political and social effects are not taken in account. Impact category Triticale Firewood Wheat straw RME Biogas Greenh. effect Mio. t CO2 - 1.81 - 1.49 -1.45 - 1.05 - 3.64 Acidification 1000 t SO2 - 1.03 - 0.481 0.553 3.04 10.6 Eutrophication 1000 t NO3 12.2 1.216 0.910 - 7.74 6.36 Summer smog t Ethylene eq. - 48 19 129 - 122 - 2020 Nitrous oxide t N2O 215 - 22 151 1610 13 Feasibility Realistic Ambitious Possible Ambitious Impossible A negative sign means “advantage for bioenergy” Impacts for 20 PJ fossil fuel saved All types of biofuel are well suited to reduce greenhouse gas emissions in substantial quantities. The highest effect per unit can be reached with biogas. The effects of triticale, firewood and straw are similar, the difference is caused by the different fossil fuel counterpart. Biodiesel leads to the lowest effect. With all biofuels acidification, eutrophication, summer smog and human toxicity will not be changed dramatically. Except for RME the same results can be observed with N2O. RME would increase the N2O burden from 9,000 t/a to 10,600 t/a. With Triticale, wood, straw and rape seed a saving of 20 PJ can be reached by each, energy from biogas cannot be produced in the afforded quantity.

Bioenergy Update 10-02 - General*Bioenergy