Bioethanol from waste: Life cycle estimation of the greenhouse gas saving potential

This paper considers two alternative feedstocks for bioethanol production, both derived from household waste—Refuse Derived Fuel (RDF) and Biodegradable Municipal Waste (BMW). Life Cycle Assessment (LCA) has been carried out to estimate the GHG emissions from bioethanol using these two feedstocks. An integrated waste management system has been considered, taking into account recycling of materials and production of bioethanol in a combined gasification/bio-catalytic process. For the functional unit defined as the ‘total amount of waste treated in the integrated waste management system’, the best option is to produce bioethanol from RDF—this saves up to 196 kg CO₂ equiv. per tonne of MSW, compared to the current waste management practice in the UK.However, if the functional unit is defined as ‘MJ of fuel equiv.’ and bioethanol is compared with petrol on an equivalent energy basis, the results show that bioethanol from RDF offers no saving of GHG emissions compared to petrol. For example, for a typical biogenic carbon content in RDF of around 60%, the life cycle GHG emissions from bioethanol are 87 g CO₂ equiv./MJ while for petrol they are 85 g CO₂ equiv./MJ. On the other hand, bioethanol from BMW offers a significant GHG saving potential over petrol. For a biogenic carbon content of 95%, the life cycle GHG emissions from bioethanol are 6.1 g CO₂ equiv./MJ which represents a saving of 92.5% compared to petrol. In comparison, bioethanol from UK wheat saves 28% of GHG while that from Brazilian sugar cane – the best performing bioethanol with respect to GHG emissions – saves 70%. If the biogenic carbon of the BMW feedstock exceeds 97%, the bioethanol system becomes a carbon sequester. For instance, if waste paper with the biogenic carbon content of almost 100% and a calorific value of 18 MJ/kg is converted into bioethanol, a saving of 107% compared to petrol could be achieved. Compared to paper recycling, converting waste paper into bioethanol saves 460 kg CO₂ equiv./t waste paper or eight times more than recycling.     

Determination of polycyclic aromatic hydrocarbons in dry tea

Twenty-eight different tea samples sold in the United States were evaluated using high-performance liquid chromatography (HPLC) with fluorescence detection (FLD) for their contamination with polycyclic aromatic hydrocarbons (PAHs). Many PAHs exhibit carcinogenic, mutagenic, and teratogenic properties and have been related to several kinds of cancer in man and experimental animals. The presence of PAHs in environmental samples such as water, sediments, and particulate air has been extensively studied, but food samples have received little attention. Eighteen PAHs congeners were analyzed, with percentage recovery higher than 85%. Contamination expressed as the sum of the 18 analyzed PAHs was between 101 and 1337 μg/kg on dry mass and the average contents in all of the 28 examined samples was 300 μg/kg on dry mass. Seven of the congeners were found in all samples with wide ranges of concentrations as follows: fluorene (7–48 μg/kg), anthracene (1–31 μg/kg), pyrene (1–970 μg/kg), benzo(a)anthracene (1–18 μg/kg) chrysene (17–365 μg/kg), benzo(a)pyrene (1–29 μg/kg), and indeno(1,2,3-cd)pyrene (4–119 μg/kg). The two most toxic congeners benzo(a)pyrene and dibenzo(a,h)anthracene were found at high concentrations only in Earl Grey Twinnings, Earl Grey Harney& Sons Fine Teas, and Chai Ultra Spice Black Tea Twinnings. Six PAH congeners are considered as suspected carcinogens (U.S.EPA), formed the basis of the estimation of the toxic equivalent (TEQ), Chai Ultra-Spice Black Tea Twinnings had the highest TEQ (110.9) followed by two grey tea samples, Earl Grey Harney & Sons Fine Tea (57.7) and Earl Grey Twinnings (54.5). Decaffeinated grey teas had the lowest TEQs, decaffeinated Earl Grey Bigelow (9.4) and Green Tea Honey Lemon Decaffeinated Lipton (9.6).     

Review of drivers and barriers for nuclear power in the UK

There has been resurgence in interest in new nuclear power stations over the last couple of years. The UK Government has taken steps to encourage the private sector to build new stations in the UK, a change in its previous neutral stance toward nuclear power. This paper examines the change in government policy asking what drivers have led to this decision and what barriers were preventing new nuclear power in the past and what barriers are still faced by both government and industry. Three main drivers are discussed: security of energy supply; diminishing energy generation capacity; and climate change. The paper also examines other key factors that play a part in facilitating a shift in government policy, namely economics, public perception and waste management policy. Barriers are identified through examination of public perception, and policy. The changes to the planning system are also discussed. The paper concludes by comparing drivers and barriers for other technologies and contrasting the UK experience with that of other countries.