Matteo Prussi

Oil production by the marine microalgae Nannochloropsis sp. F&M-M24 and Tetraselmis suecica F&M-M33.

Nannochloropsis sp. F&M-M24 and Tetraselmis suecica F&M-M33 were cultivated outdoors in Green Wall Panels under nutrient deficiency to stimulate oil synthesis. Under nitrogen deprivation, Nannochloropsis attained average biomass and lipid productivities of 9.9 and 6.5 g m(-2) day(-1), respectively. Starved Tetraselmis cultures achieved a biomass productivity of about 7.6 g m(-2) day(-1) and a lipid productivity of 1.7 g m(-2) day(-1). Lipids represented 39.1% and 68.5% of non-starved and starved Nannochloropsis biomass, respectively. Starvation did not increase lipid content in Tetraselmis biomass. Important differences in lipid classes and in fatty acid composition were observed under the different cultivation conditions for both microalgae.

Evaluation of a Micro Gas Turbine Fed by Blends of Biomass Producer Gas and Natural Gas

Small scale gasification is a promising technology for bioenergy generation. Reciprocating engines are usually combined with downdraft gasifiers, nevertheless this approach is associated with high emissions, in particular CO and NOx and with a limited co-generation potential. MGT technology, rapidly improved during the last years, offers the possibility to reduce the levels of pollutants in the exhaust. Moreover they offer some other advantages in the small size range, such as a higher exhaust gas flow at higher temperatures, while maintaining a similar net electric efficiency. Evaluating the possibility to couple a MGT with a gasifier, the quality of the producer gas is also a relevant issue. In this work an overview of the typical gas quality produced by existing small scale gasifiers is carried out; moreover, a review regarding the syngas combustion in GT is realized, considering GT requirements related to gas composition. Co-firing with natural gas is considered, in order to reduce the modification needed to the engine. An evaluation of the proper range of mixing is then carried out. The performances of a commercial 100 kWel MGT are then simulated by means of an “in-house” developed code named AMOS (Advanced MGT system Operation Simulator). This tool allows to perform a steady-state matching analysis based on the characteristic lines of each component, when using a low calorific gas in a MGT. Producer gas and natural gas mixtures are considered and a parametric study is carried out. Performances were computed considering MGT full-load operation.Copyright

Process Analysis and Modelling for 2nd Generation Lignocellulosic Bioethanol Production

In the present work, the most promising processing technologies for next generation ethanol production are assessed. A literature-based comparative analysis of the technologies in terms of yield, efficiency, feedstock and level of process integration is carried out in order to identify the most interesting ones. The aim of this paper is the analysis and validation based on literature data of a process simulation performed using the software Aspen Plus. The model is intended to understand the major process steps and focuses on the main aspects from an energy engineering point of view. Moreover it provides an useful tool for preliminary analysis of different configurations. Crucial aspects include high pretreatment yield, efficient hexose and pentose fermentation, enzyme strain development and solid residue valorization for process heat and power generation. Energy and mass balances are modeled, so to allow a comparison among different technological solutions. A plant able to process 240,000 kt/y of biomass is modeled, showing a production capacity of about 40,000 kt/y of ethanol. Ethanol productivity is over 300 L/t of dry biomass, and net process energy efficiency is calculated over 35%. The model developed focuses on the main steps of the production process allowing for further development or process optimization.

Pure vegetable oil for energy and transport

Pure Vegetable Oil (PVO) is a 100% renewable fuel obtained from oil crops. PVO can be produced in a distributed manner in rural areas and commercial technologies almost exist for energy and transports, making possible to develop small scale chains, suitable for both industrialised as well as developing countries. The aim of the research work is to investigate over a three-year period the complete PVO chain under Italian conditions, i.e., crop selection, plantation and harvesting, seed drying and storage, oil extraction, cake (coproduct) valorisation and PVO use in small generators, cogenerators, micro gas turbines and greenhouse/school heating systems, supporting experimental work with environmental and socio-economic studies. The aim of the present paper is to present the results obtained at the end of the first year, as regards oil production in both cold decentralised systems and industrial systems, as well testing of the oil in a modified tractor. The PVO produced in the cold press met the current DIN specifications for PVO in engines and the performance of the tractor was very similar to standard tractors. [Received: January 29, 2009; Accepted: March 4, 2009]

Assessment of the EU target on renewable energy for transport in the framework of the European vegetable oil sector

Biofuels is currently driving the interest in bioenergy sector. The recently issued Renewable Energy Directive (2009/28/EC) confirms the 10% target, set by the EC, for energy from renewable sources in transport. The European Union is the largest producer of biodiesel in the world and biodiesel is also the most important biofuel used in the EU. The aim of this paper is to investigate the biomass feedstock requirement, under different scenarios, with a focus on vegetable oils. The European production potential is compared with the amount of biomass required to meet the target on biofuels. Next generation biofuels and alternative feedstock for first generation pathways are considered as well as the share of biomass import. The scenario proposed allows to estimate the land required to meet the target at 2020 on biodiesel. Assuming different contribution of the next generation biofuels, from the 10% to the 30% is possible to estimate the contribution of first generation biodiesel. The results showed that, considering the total European arable land, this production will utilise 9–13%.

Oilseed pressing and vegetable oil properties and upgrading in decentralised small scale plants for biofuel production

Vegetable oils became a very popular bioliquid for renewable power and transport applications. At local level, the short chain production of vegetable oils is currently important in terms of sustainability and use of rural area. This present work investigates the development of vegetable oils production chain in the Tuscany territory, focusing also to valorisation of the co-products (i.e., oil cake). The work is based on the study of the cultivation of rapeseed and sunflower, and the creation of an extraction plant based on cold-screw pressing technology, in order to obtain a raw vegetable oil suitable as biofuel. The German DIN 51623 standard was adopted to investigate the quality of vegetable oils obtained from different oil crops. Vegetable oils quality was evaluated by comparing the oil produced by a bench press at lab scale, comparing the results in terms of process yields and lipid fraction recovered. Due to the high phosphorous content of rapeseed oil, out of the DIN limits, an experimental procedure to remove P content and restore the oxidation stability of the oils was performed. The results showed a substantial P reduction by adding 2 wt% of P-removing additive. The oil cake properties were evaluated in view of its potential use for bioenergy production, in particular in terms of metals content. [Received: December 5, 2015; Accepted: September 20, 2016]