GB2511285A

GB2511285A - A novel pumped storage hydroelectric construction method

Info

Publication number: GB2511285A
Application number: GB1223338.3A
Authority: GB
Inventors: Richard John Heppenstall
Original assignee: Individual
Current assignee: Individual
Priority date: 2012-12-22
Filing date: 2012-12-22
Publication date: 2014-09-03
Anticipated expiration: 2032-12-22
Also published as: GB2511285B; GB201223338D0

Abstract

A pumped storage hydroelectric system uses flexible bladder storage tanks 1, 2 for at least one of the upper or lower reservoirs. This allows use of pumped storage without the need to create traditional reservoirs. It is also proposed to use lightweight Polyethylene or glass fibre reinforced (GRP) pipes. The pump/turbine(s) 3 and control equipment may be housed in transportable containers.

Description

A Novel Pumped Storage Hydroelectric Construction Method

Field of Invention

[0001] The invention relates to a novel construction method of a pumped storage hydroelectric system which allows a wider deployment of the technology; particularly for intermittent energy generation assets.

Background of Invention

[0002] To allow a better balance between supply and demand on the electrical power distribution network, there is a requirement to store some of the energy produced from intermittent energy generation assets such as wind turbines at times of low consumer demand and to release the energy at times of higher demand. The most widely used form of grid scale energy storage technology is the pumped storage hydroelectric plant. Other energy storage technologies have yet to demonstrate cost effectiveness and long term viability at grid scale.

[0003] Pumped storage hydroelectric plants operate on the principle of pumping water from a low elevation reservoir to an upper reservoir then allowing the water to flow back to the lower reservoir through a water turbine, thereby generating power in the process. Due to the restricted geography, high capital and environmental costs of building reservoirs, the interconnection between them and altering natural water courses, the widespread use of pumped storage hydroelectric plants has been restricted to a few large scale special sites to offset the high initial capital investment and operating costs. These special sites typically have at least one existing natural lake to offset the cost.

[0004] Many types of turbine and pump have been utilised in previous pumped storage hydroelectric plants. The majority of the plants employ pump turbines which can act as both a turbine to generate power from the working fluid and as a pump to refill the upper reservoir. Pump turbines operate at a lower combined efficiency than separate turbines and pumps can achieve, but can reduce capital investment and system complexity. Pump turbine design has been improved over the years and round trip efficiency (net system efficiency over a complete storage cycle) can be typically over 80%. Other schemes utilise the system pumps as turbines in so called Pump as Turbine (PAT) operation. Many pumps can operate as turbines but the trade-off is a loss of efficiency set against the much lower capital cost. Typically PAT operation can result in a round trip efficiency of circa 70%. The main benefits of utilising PAT equipment is that pumps are readily available and that as standard pumps their cost is considerably lower than specially made turbines. In some plants separate pumps and turbines or pump turbines may be utilised.

[0005] Shipping, intermodal or ISO containers have been widely used for housing plant equipment due to their low cost, ease of transport and long life. Typically constructed from steel they are supplied in 2Oft or 4Oft lengths and can be customised to have standard doors and other modifications. The benefit of housing plant equipment within standard containers is that they can be constructed at a factory which greatly reduces installation time and costs.

[0006] Bladder or Pillow tanks (citerne souple) are flexible material tanks used to store fluid.

They have been in widespread use in irrigation and fluid storage applications worldwide since their market introduction in the 1950's (Mr. André LABARONNE, patent FR1460825, 19 October 1965). Bladder tanks are typically manufactured from PVC coated polyester and can be used to store many different types of fluid including water, chemicals and fuels. Bladder tanks are constructed from shaped pieces of material or tissue and joined using high frequency welding techniques. The materials used are selected for chemical resistance and stability against ultraviolet radiation. Connection fittings and breather vents are bonded or welded through the material as required dependent upon the application.

[0007] Polyethylene (PE) and Glass Reinforced Plastic (GRP) pipes are utilised in many industries due to their high relative strength and low cost. Standard pipes are readily available in many diameters and standard lengths.

Description of the Invention

[0008] The present invention proposes replacement of the reservoir elements of a traditional pumped storage hydroelectric system with interconnected flexible bladder or pillow tanks and the use of turbine/pump and control equipment housed in a transportable containers or power modules. Lightweight PE or GRP pipes are used to connect the upper and lower flexible tanks to minimise capital and installation cost.

[0009] The use of flexible bladder tanks, lightweight interconnection pipework and transportable power modules allows the wide scale deployment of pumped storage hydroelectric systems to locations and at smaller scales not previously viable due to geography, cost and environmental impact with the current state of the art. An increase of the stored energy of the system can be obtained by installing additional bladder tanks in series. A benefit of the system described is that the amount of stored energy can be tailored to suit the application and then can be scaled up or down, at a future time, when the requirement may change by either adding or removing tanks.

[0010] Operating as a traditional pumped storage hydroelectric plant, the invention differs in that as a fully closed system it prevents evaporation and fluid loss and allows the fluid to be treated and filtered to maintain its quality and prevent system efficiency losses through bacterial growth and contamination.

[0011] The transportable power modules will house the pump, turbine and control equipment as well as any filtration, dosing and monitoring equipment. Separate or combined modules may be utilised dependent upon the application.

[0012] All of the system components are easily deployable by the road network and can be easily craned or moved into position with standard site equipment. The flexible bladder tanks will be installed on to prepared levelled areas surrounded by a small raised berm for safety purposes. The power modules will be sited on a level hard-cored or concrete pad. It is expected that a chain link fence or similar will be installed for site security.

[0013] The interconnection pipelines are likely to be buried in a shallow trench in most applications for aesthetic reasons and will hence take the longest time to install. In some applications, it may be practicable to surface mount the pipelines which would allow rapid deployment and installation of the system.

[0014] In the case of intermittent generation assets such as onshore wind turbines, the invention allows deployment of a scaled energy storage system alongside the generation asset to further reduce system costs by sharing the electrical interconnector to the main distribution grid network and local infrastructure such as the service road.

[0015] Installation benefits to the flexible nature of the system are that; the system can be designed around the landscape rather than being forced upon it; poor quality land can be utilised; minimal landscaping and environmental damage occurs either during installation or decommissioning.

[0016] Due to the closed nature of the described system the working fluid is not limited to water. Using denser fluid for example would allow for greater energy storage in the same fixed volume tank but may require modifications to the pump/turbine elements due to fluid property changes such as viscosity. Use of brine solutions in the described system would have the benefit of lowering the freezing point of the solution and may alleviate the need for other forms of frost protection. Other fluids types considered, but not limited to, include oils, heavy liquids and suspensions.

[0017] It is expected that any fluid losses from the closed system will amount to a small volume and can be topped up via a small auxiliary tank or, in the case where water is being used as the fluid, from rainfall catchment from the roof of the power module.

[0018] To prevent fluid freezing problems, the fluid may be dosed with antifreeze. In some applications other measures may be employed to prevent freezing and frost damage such as, but not limited to; trace heating the pipework; trace heating pads installed beneath the bladder tanks; heated bladder tank covers; circulating fluid.

[0019] To further prevent ultraviolet (UV) radiation damage to the bladder tanks, covers may be fitted to block the UV. These covers may also be insulated to aid heat retention in cold weather to further prevent problems with freezing.

[0020] In some applications, a battery backed solar photovoltaic system may be used to increase the system efficiency by supplying the parasitic power requirements of the power modules.

[0021] In some applications, it may be better suited to utilise an existing natural water source for either the lower or upper flexible bladder tanks. In these open system cases, additional screening and filtering equipment will be required to prevent damage to the local ecology.

[0022] In some applications, the system may be configured to provide backup power in the event of a loss of electrical supply to critical power users such as data centres, hospitals and manufacturing processes. It may be possible in some of these applications to cross utilise existing plant process fluid.

[0023] The invention will now be described by way of examples and with reference to the accompanying drawings in which: Figure 1 shows the system schematic. Flexible bladder tanks 1 & 2 are installed at different elevations connected to the power module 3 by a pipeline 4. In storage mode the power module pumps fluid from the lower bladder tank 2 into the higher bladdertank 1 using electrical power from the local grid network. In discharge mode, fluid from the higher bladder tank 1 is gravity fed through the turbine in the power module 3 to generate power back on to the electrical power grid. The fluid discharges back into the lower bladder tank 2.

Figure 2 shows an alternate system schematic. Flexible bladder tank 5 is installed at a higher elevation than an existing water source 6 and connected to the power module 7 by a pipeline 8. In storage mode the power module pumps fluid from the existing water source 6 into the higher bladder tank S using electrical power from the local grid network. In discharge mode, fluid from the higher bladder tank 5 is gravity fed through the turbine in the power module 7 to generate power back on to the electrical power grid. The fluid discharges back into the existing water source 6.

Figure 3 shows an alternate system schematic. Flexible bladder tank 10 is installed at a lower elevation than an existing water source 9 and connected to the power module 11 by a pipeline 12. In storage mode the power module pumps fluid from the flexible bladder tank 10 into the existing water source 9 using electrical power from the local grid network. In discharge mode, fluid from the existing water source 9 is gravity fed through the turbine in the power module 11 to generate power back on to the electrical power grid. The fluid discharges back into the flexible bladder tank 10.

Claims

Claims 1. A pumped storage hydroelectric system comprising of high and low level flexible reservoir bladder tank elements.
2. A pumped storage hydroelectric system according to claim 1, in which transportable containerised housings or modules are utilised to house the pump, turbine and control equipment of the system.
3. A pumped storage hydroelectric system according to claim 1, which operates as a closed fluid system.
4. A pumped storage hydroelectric system according to claim 1, where the working fluid is not water.
5. A pumped storage hydroelectric system according to claim 1, where an existing or new building or structure is utilised to house the pump, turbine and control elements of the system.
6. A pumped storage hydroelectric system comprising of high level flexible reservoir bladder tank element and an existing low level water source.
7. A pumped storage hydroelectric system according to claim 6, in which transportable containerised housings or modules are utilised to house the pump, turbine and control equipment of the system.
8. A pumped storage hydroelectric system according to claim 6, where an existing or new building or structure is utilised to house the pump, turbine and control elements of the system.
9. A pumped storage hydroelectric system comprising of low level flexible reservoir bladder tank element and an existing high level water source.
10. A pumped storage hydroelectric system according to claim 9, in which transportable containerised housings or modules are utilised to house the pump, turbine and control equipment of the system.
11. A pumped storage hydroelectric system according to claim 9, where an existing or new building or structure is utilised to house the pump, turbine and control elements of the system.