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The anaerobic digestion (AD) of distillery by-products presents benefits such as greenhouse gas (GHG) emission savings and electricity savings, as well as drawbacks such as reduced animal feed and protein production and the potential import of animal feeds. This work balances these benefits and drawbacks using compromise programming (CP). The best combination of byproducts (from 9,261 scenarios) to use in AD was selected based on criteria chosen by management of a large distillery. The use of all by-products maximises benefits and drawbacks; the contrary also applies. When benefits and drawbacks are equally important, CP recommends using 50% of available draff, 50% of available thick stillage, and 55% of available thin stillage. The best combination when accounting for criteria weights chosen by distillery management is the use of 100% of available draff and 100% of available thick stillage. This could replace 48% of natural gas consumption at the distillery, reduce Scope 1 emissions by 45%, achieve a Scope 3 emissions savings of 22% of current Scope 1 emissions, and reduce electricity consumption in the feeds recovery plant of the distillery by 63%. Protein loss of 9,618 t could require the import of 19.59 kilo-tonne wet weight of material (ktwwt) of distillers grains and 9.15 ktwwt of soybean meal. If different criteria or criteria weights were used, a different result would be recommended. The methodology developed herein can aid in decarbonising the food and beverage industry by allowing decision-makers to balance the benefits and drawbacks of AD while accounting for subjective preferences. [ABSTRACT FROM AUTHOR]

This paper details the analysis of biochemical methane potential (BMP) assessment of 83 substrates, which may be deemed as: first generation substrates (food crops); second generation (grasses and wastes); and third generation (seaweed). Significant variation in the BMP of a substrate may be found depending on for example, season and method of harvest. This could lead to significant discrepancy between energy production at the design stage and in operation of the facility. For example the BMP of dairy slurry varied from 175 L CH 4 kg −1 VS in autumn (cattle fed on concentrate at end of farming year) to 239 L CH 4 kg −1 VS in the summer when cattle are fed fresh grass. Grass ranged from 156 (for hay) to 433 L CH 4 kg −1 VS for first cut baled silage. Saccharina latissima (brown seaweed) generated a higher BMP 36.4 m 3 CH 4 t −1 than summer dairy slurry 16 m 3 CH 4 t −1 . In terms of a national resource, the cheapest and most sustainable source of biomethane will be from wastes, but the resource is finite. Biomethane from wastes could satisfy 18.4% of transport energy in Ireland. Larger resources will require third generation substrates such as seaweed. [ABSTRACT FROM AUTHOR]

Macro-algae represent an ideal resource of third generation biofuels, but their use necessitates a refinement of commonly used anaerobic digestion processes. In a previous study, contrasting mixes of dairy slurry and the macro-alga Ulva lactuca were anaerobically digested in mesophilic continuously stirred tank reactors for 40 weeks. Higher proportions of U. lactuca in the feedstock led to inhibited digestion and rapid accumulation of volatile fatty acids, requiring a reduced organic loading rate. In this study, 16S pyrosequencing was employed to characterise the microbial communities of both the weakest (R1) and strongest (R6) performing reactors from the previous work as they developed over a 39 and 27-week period respectively. Comparing the reactor communities revealed clear differences in taxonomy, predicted metabolic orientation and mechanisms of inhibition, while constrained canonical analysis (CCA) showed ammonia and biogas yield to be the strongest factors differentiating the two reactor communities. Significant biomarker taxa and predicted metabolic activities were identified for viable and failing anaerobic digestion of U. lactuca. Acetoclastic methanogens were inhibited early in R1 operation, followed by a gradual decline of hydrogenotrophic methanogens. Near-total loss of methanogens led to an accumulation of acetic acid that reduced performance of R1, while a slow decline in biogas yield in R6 could be attributed to inhibition of acetogenic rather than methanogenic activity. The improved performance of R6 is likely to have been as a result of the large Methanosarcina population, which enabled rapid removal of acetic acid, providing favourable conditions for substrate degradation. [ABSTRACT FROM AUTHOR]

The use of Monte Carlo simulation in construction cost analysis is of interest to construction professionals as part of the risk analysis of construction projects. In recent high profile publications the presentation of Monte Carlo simulation based cost analysis overplays the importance of the choice of which distribution to use to represent input variables and underplays the importance of assessing and including correlations between the variables. The British literature also overplays the suitability of the beta distribution to represent input variables. This paper addresses these issues using a data set comprising elemental rates from 216 office buildings drawn from the BCIS of the RICS. Using a chi-squared test for goodness of fit it is shown that lognormal distributions are superior to beta distributions in representing the data set. Simulation runs of the cost model including and excluding correlations show that correlations must be included in Monte Carlo simulation otherwise the analysis leads to serious misassessment of risk. Simulation results show also that the effect of excluding correlations is more profound than the effect of the choice between lognormal and beta distributions. [ABSTRACT FROM AUTHOR]

This paper reviews literature about building maintenance in developing countries. A search of published sources revealed a disappointingly small and fragmented literature relating mostly to technical and managerial matters. These are presented in the paper under the headings: the effect of climate, design and materials choice, construction and maintenance personnel, managerial systems and financial systems. Few sources cover the economics of building maintenance and none discuss the important aspect of how building maintenance impacts on broader economic and development issues. The paper discusses building maintenance in the context of the six forms of capital usually encompassed in World Bank development projects (human, institutional, cultural, natural, physical, and financial) and as such contributes to the economic analysis of building maintenance. Several areas needing further research are noted. [ABSTRACT FROM AUTHOR]