Subsea Pumped Hydro Storage

Examensarbete för masterexamen

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Type: Examensarbete för masterexamen
Master Thesis
Title: Subsea Pumped Hydro Storage
Authors: Erik, Almen John
Johan, Falk
Abstract: A new technology for energy storage called Subsea Pumped Hydro Storage (SPHS) has been evaluated from a techno-economical point of view. Intermittent renewable energy sources are becoming more common in the electricity grid; hence the need of regulating power is increasing. One way of balancing the demand of electricity with the production is by implementing energy storage in the system. This thesis has assessed such a concept, which is a sea-based version of the already existing pumped hydro storage technology. A SPHS unit is composed of a hollow structure placed at the seabed which can be emptied of water by the use of a pump at times of low demand and high production of electricity in the system, the unit is at that point charged. When this excess energy is needed in the system water is allowed to flow back into the cavity through a turbine and thus generating electricity. This work has defined which components are needed for the concept to function and how these are implemented to create a complete technical system. In order to compare SPHS to alternative solutions for energy storage, so called Key Performance Parameters were determined and quantified. The two technologies pumped hydro storage (PHS) and compressed air energy storage (CAES) were used for comparison with the SPHS concept due to their similar operation characteristics. The last step of the analysis was performed with an energy systems model where energy storage was included in the Danish electricity system due to its high penetration of fluctuating wind power. A number of scenarios were examined and it was shown that at larger installation depths the capital cost was reduced due to a lower material requirement. It should however be clarified that the costs for installation at large depths are very uncertain. Compared to PHS (with a levelized cost of electricity, LCOE, of 187-278 €/MWh) it was concluded that the subsea pumped hydro storage concept (with a LCOE of 212-336 €/MWh) needs to be developed further in order to be competitive from a cost point of view. Furthermore, unless subsidies for the delivered electricity are implemented the storage technology will not yield a sufficient income when operating on the spot market as a buyer and seller of electricity. A better alternative could be to connect the technology to an offshore wind power plant where the wind energy can be stored directly as the wind turbine drives the pump in the storage unit mechanically. This would imply that electricity, which is more expensive than any other fuel, doesn’t have to be bought at market price and that the wind power plant and storage unit become one integrated facility.
Keywords: Energi;Hållbar utveckling;Mekanisk energiteknik;Energy;Sustainable Development;Mechanical energy engineering
Issue Date: 2013
Publisher: Chalmers tekniska högskola / Institutionen för energi och miljö
Chalmers University of Technology / Department of Energy and Environment
Series/Report no.: Examensarbete. T - Institutionen för energi och miljö, Avdelningen för energiteknik, Chalmers tekniska högskola
Collection:Examensarbeten för masterexamen // Master Theses

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