Integration of Farm Fossil Fuel Use with Local Scale Assessments of Biofuel Feedstock Production in Canada

A latent heat thermal energy storage unit is being integrated into a heat- and power cogeneration plant in Saarland, Germany. This storage unit system will act as an intermediate backup to a heat recovery steam generator and gas turbine and is therefore situated in parallel to this unit, also between the feedwater pumps and the steam main. The steam required is superheated, with a nominal thermal power of 6 MW. The storage unit needs to provide steam for at least 15 minutes, resulting in a minimum capacity of 1.5 MWh. Integration of this storage unit will increase efficiency and decrease fossil fuel use by reducing the use of a conventional backup boiler, while maintaining the steam supply to the customer. The detailed design and a partial build of the storage unit has to-date been successfully concluded, as well as system design and build. Hot and cold commissioning of the storage unit, including filling of the storage unit, will commence following the completion of the storage unit. With the integration of this storage unit, fossil fuel use will be reduced in this power plant. Additionally, the production of superheated steam at a high power level in a latent heat storage unit and a comparison with simulation tools will be possible. This project includes the design, build, commissioning and testing of the storage unit. The paper discusses the detailed design of the storage and system, including the simulations of the system integration.

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Growth and fatty acid characterization of microalgae isolated from municipal waste-treatment systems and the potential role of algal-associated bacteria in feedstock production

PeerJ ◽

10.7717/peerj.1780 ◽

2016 ◽

Vol 4 ◽

pp. e1780 ◽

Cited By ~ 12

Author(s):

Kevin Stemmler ◽

Rebecca Massimi ◽

Andrea E. Kirkwood

Keyword(s):

Fatty Acid ◽

Environmental Sustainability ◽

Municipal Wastewater ◽

Unsaturated Fatty Acids ◽

Waste Treatment ◽

Commensal Bacteria ◽

Biodiesel Production ◽

Municipal Wastewater Treatment ◽

Biofuel Feedstock ◽

Feedstock Production

Much research has focused on growing microalgae for biofuel feedstock, yet there remain concerns about the feasibility of freshwater feedstock systems. To reduce cost and improve environmental sustainability, an ideal microalgal feedstock system would be fed by municipal, agricultural or industrial wastewater as a main source of water and nutrients. Nonetheless, the microalgae must also be tolerant of fluctuating wastewater quality, while still producing adequate biomass and lipid yields. To address this problem, our study focused on isolating and characterizing microalgal strains from three municipal wastewater treatment systems (two activated sludge and one aerated-stabilization basin systems) for their potential use in biofuel feedstock production. Most of the 19 isolates from wastewater grew faster than two culture collection strains under mixotrophic conditions, particularly with glucose. The fastest growing wastewater strains included the generaChlorellaandDictyochloris. The fastest growing microalgal strains were not necessarily the best lipid producers. Under photoautotrophic and mixotrophic growth conditions, single strains ofChlorellaandScenedesmuseach produced the highest lipid yields, including those most relevant to biodiesel production. A comparison of axenic and non-axenic versions of wastewater strains showed a notable effect of commensal bacteria on fatty acid composition. Strains grown with bacteria tended to produce relatively equal proportions of saturated and unsaturated fatty acids, which is an ideal lipid blend for biodiesel production. These results not only show the potential for using microalgae isolated from wastewater for growth in wastewater-fed feedstock systems, but also the important role that commensal bacteria may have in impacting the fatty acid profiles of microalgal feedstock.

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