R&D Project 8 – Pumped storage flow rates project

Pump hydro storage system is a fast pace and appropriate response to buffer intermittent fluctuations of renewable energy. The objective of the project is to develop the understanding of pros and cons of a hydro power pumped storage system, and also develops a modelling approach that deals with the energy outputs in relation to flow rates. In spite of all the numerous advantages of this system the contribution of the three main factors; power capacity, generator capacity and the generator ramp rates, are also considered. 

The utilization of energy in the form of electricity is the ultimate need of the modern era. This energy can be produced by utilizing either renewable resources or non-renewable resources. Renewable recourses have become famous and more accepting because of their 0 to very low operational emission measures and cost effectiveness. When it comes to hydropower generation, wind energy generation or biogas then we have constant and controllable power while wind and solar energy generation have restrictions due to seasonal and environmental impacts. To overcome this fluctuations or interruptions, a storage energy technique is developed which works in name of dispatch able technologies. It works in a way of regulating voltages and frequencies by buffering. Thanks to this storage and buffering phenomena we fulfill the over works loads. In these methods, where efficiency is important, there cost plays also an important role because every unit produced by which technology has its own value. (Mohit 2018) 

In all of the above discussed technologies, hydropower generation is the most trustable, durable and adoptable storing and peak load working technology which actually convert the maximum renewable capacity to electrical power. Initially, turbines are used to extract the water potential in the form of mechanical energy and then a generator for further conversion of mechanical to electrical. The turbine development leads to control the variable load requirement by analyzing the blade movements and controlling the turbine speed. The ability of generation accompanied by pumping power to the higher reservoirs at the time of low loads. Spinning reservoir can also be linked with hydropower for compensating any disruption in generation. 

Pumped Storage Hydro System

This system works by utilizing the energy of water at stored at height. It all happens in conversion of potential energy stored in the head height. The stored energy capacity is given by the following equation: 

Where E is the stored energy, ƿwater is the density, V is the reservoir volume and h is the head height.

Modeling Approach

The modeling approach used by change in the applied energy paper with Matlab Simulink is quite appealing and match with our target. It facilitates the user by allowing the possible approach for future impacts on the grid in terms of generation. As every hydro model has multiple domains like power generation, flood control irrigation and water supply source. (Fabian 2013) 

Figure 3 – Methodology for Hydro pumped storage model 

Properties of Pumped Hydro Power

At Planning Stage 

At the very start, in the planning stage, it should be considered carefully that site location and region are feasible for the required energy demand or not. So the geological condition has its important to make sure the availability of water source, composition of electrical system and ultimately energy source development. 

Design Considerations 

As these projects are at very large surroundings and considered in mega projects so the very 1st thing to focus on is the safety standards. The 2nd consideration is the carefully and diligently designing of the pump turbine heads. All these pump hydro storage systems requires tunnel which should be in consideration. In the end to overcome the seepage, a system is installed for anti-seeping. 

Construction Stage Approach 

In the start, as it is an underground approach utilizing height energy, so all the ways including delivery system, inlet system, outlet system, ventilation system and drainage system should be with underground caverns. In all this, all design system should have a validate excavation and utilization of the earth work with sand gravel aggregate. This pump turbine hydro storage system installation is far complex than the conventional hydro turbine systems. (Yang2 2018) 

Problems in Pumped storage hydro Power 

The main restriction is due to the head limitations; like this sort of system requires high head. High head itself is not such a big issue but it leads to higher rotation speeds, longer delivery routes and ultimately makes the process complex design wise as well as cost wise. The 2nd trait of this system; handling the variable load requirement infiltrates the grid stability when it requires ultra-high grid frequencies. (Yang2 2018) 

The pressure pulsating effect is also an irritating factor and allows to compromise its features while the spiral casing design of inlet pressure. In these type of systems, no negative vacuum pressure condition can be inappropriate and thus cavitation in the draft tube inlet occurs. Due to the surrounding rock in water can cause stress proportion transmission as well. 

Economic Efficiency 

By keeping an account of the environmental and economic comparison tells that about 70 to 80 % energy recovery occurs from this system. So it’s a fantastic approach towards storing large scale electrical energy but having limitations due to restricted geographical circle and large capital cost and time. Moreover, it has nothing to do with natural or non-natural flows, it is concerned with just availability of large body of water near the reservoir. With the help of this system, grid power generation curves can be flatten which is an economical way. As it balances the base load by controlling the intermittent output so it serves cheaper than other systems. (Arsalan F. Latif 2014) 

Conclusion

The newly developed pump storage hydro power system has played its role in help improving the power supply quality, optimizing the power structure, promoting massive grid-connection of wind power, solar and other renewable energy and realizing the sustainable development of the electric energy. No doubt it has a large principle cost and seasonal, location issues but with a wise investment it would be the future as it’s not just for generation but also for survival due to water storage. 

Specific Milestone Objectives

The project comprises 3 milestones, where: 

Milestone 1 is divided into 2 milestones: 

Milestone 1A – Theoretical modelling of energy output of hydroelectric pumped storage system based on flow rates 

Milestone 1B – Theoretical modelling of round-trip losses for hydroelectric pumped storage systems 

Milestone 2 is divided into 4 milestones: 

Milestone 2A – Select sample of diverse flow rates, gradients and head-race heights and calculate levelised costs of electricity curve based on multi-variate correlation of inputs 

Milestone 2B – Collect actual data from statistically valid dataset for pumped storage schemes with less than 200m of gravity and greater than 1/10 gradient 

Milestone 2C – Study the effect of density of saline water versus fresh water on round-trip losses 

Milestone 2D – Compare actual seawater pumped storage performance of Okinawa Island vs engineering models of Snowy and Cortina 

Milestone 3 is divided into 4 milestones: 

Milestone 3A – Develop modelling tool using data gathered 

Milestone 3B – Test modelling tool against known data from existing schemes to verify accuracy and margins 

Milestone 3C – Identify factors that will impact output generation to be considered in sensitivity analysis 

Milestone 3D – Finalise modelling tool using data gathered to calculate likely actual electricity generation output based on a given set of variables with sensitivity analysis 

References

1) Arsalan F. Latif, a. S. A. A. (2014). “Investigation of Pumped Storage Hydro Electricity “. 

2) Fabian, C. A. (2013). “Buffering intermitten renewable power with hydroelectric generation.” 

3) Mohit, M. a. (2018). “Real time co-simulaiton of adjustable speed pumped storage hydro for transiet stability analysis.” 

4) Yang2, Y. W. X. a. J. (2018). “Developments and characteristics of pumped storage power station in China.”