PUMPED STORAGE HYDRO PLANTS IN BALANCING POWER FLOW

Authors: * Pranab K. Bhaduri; ** Amit K. Gangulee

Session Title: 15A – Renewable Energy Storage Systems: Enabling the Grid of the Future;

Track: Utility Integration;

Presentation Date: 09 December 2014; Time: 1:30 PM – 3:30 PM;

Session Chair Karen Bertram

Integrated Energy Services

*Senior Executive Director: Development Consultants Private Limited, Kolkata, India

** Executive Vice President: The Kuljian Corporation, Philadelphia, PA, USA

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1.0.0 Preamble

Pumped Storage Hydro Plant – an essential component of electricity network – acts by way of balancing power flow in the grid i.e. as peaking stations. During low power demand periods, water is pumped from lower reservoir to the upper one; that subsequently generates hydro power by releasing the water into the lower reservoir, running through reversible turbines/motors and sending the energy back to the grid during peak energy demands.

increased wind and solar capacity, would significantly improve grid reliability while

reducing the need for construction of additional coal, oil and gas based generation.

Underground pumped storage, using flooded mine shafts or other cavities, are

also technically possible.

Pumped storage plants are, however, high capital-intensive, ecology-sensitive and

also require long implementation times. Nevertheless, with rising electricity prices and

an increasing use of intermittent energy sources, it can be very economical to store

electricity for later use.

USD 600 million Purulia Pumped Storage Plant (4 units of 224 MW each) at Ayodhya Hill in

Purulia District of West.Bengal state, in India, is one such plant that has been commissioned in

the recent past.

The paper primarily deals with Pre-feasibility Study based on high level field

reconnaissance, Survey of India topographic sheets and various desk studies – power

scenario, hydrologic& water availability, geologic, etc., and initial field Survey& Field

Investigation – in order to establish the phase-wise development of the project, jointly

by Development Consultants, India, and Harza Engineering, USA, in the year 1979-80.

Pumped storage – a renewable

green energy portfolio - is a

proven grid-scale energy

storage technology; and, can

also run on other renewable

energy sources like wind, during

off-peak periods, for pumping up

the water. Developing additional

hydropower pumped storage,

particularly in areas with recently

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Amongst others, initial field survey & investigation works, studies/ analyses, designs &

engineering covering the paper are:

Demand & Supply Scenario of Power in India, Peak hour Power Deficit:

Pattern of Peak Demand and Energy Requirement;

The Project, Site Visit, High level Reconnaissance and Initial Investigations;

Hydrologic Studies and Water Availability;

Project Components – Sizing & Layout;

Environmental & Social Impact Studies;

Project Cost Estimates and Implementation Schedule;

Detailed Field Surveys and Investigations;

Project Development & Economics

2.0.0 Demand & Supply Scenario of Power in India, Peak hour Power Deficit 2.1.0 Variation in Power Demand

We are aware, every power system displays variability in demand between Seasons and various hours of a day. There are also considerable variations in electricity demand between weekdays, weekends or holidays. In India, in 2010-11 peak demand in the power system was 122 GW, while the average demand was only 98 GW. The minimum demand in the system was of the order of 75 GW. 2.2.0 Eastern Region of India Scenario

Again, in the Eastern Region of the country, where the state of West Bengal

is a part, shows the variation in demand (MW)/ availability(MU) in last several years: (Ref. Load Generation Balance Report 2014-15 (CEA))

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2.3.0 Peak Demand Power Scenario in West Bengal

The states in India are reeling under pressure to solve the peak demand of electricity; and, are trying out various options to tie up with the situation. In the first quarter of the year 2008, West Bengal State Electricity Distribution Corporation

18,000

17,000

16,000

15,000

14,000

13,000

12,000

11,000

10,000

Peak Demand (MW)

Energy Requirement (MU)

11,000

10,500

10,000

9,500

9,000

8,500

8,000

7,500

7,000

6,500

6,000

2010-11

2011-12

2012-13

2013-14

2014-15

(projected)

2010-11

2011-12

2012-13

2013-14

2014-15

(projected)

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Limited (WBSEDCL) commissioned the Purulia Pumped Storage Power Project (PPSP) as a step forward in the direction to meet the peak hour demand. As per Central Electricity Authority (CEA), Government of India report, the peak hour demand for March 2008 in the state of West Bengal was 5,379 MW and supply was 4,754MW. Despite the commissioning of the PPSP, the overall peak hour power deficit was 625 MW (about 12% deficit).

The scenario would have been more critical in the event of more power-intensive industrialization in the region, less captive power facilities in industrial units, and more domestic consumption as happens in sustainable economic growth of the region, warranting more buying power of the citizens.

The per capita annual Energy Consumption in combined rural & urban India is, again, much lower than other industrialized and high income countries, as evident from the following table:

YEAR PER CAPITA ANNUAL CONSUMPTION (KWH)

INDIA * CHINA FRANCE PAKISTAN UK USA

2005-06 631.4

2006-07 671.9

2007-08 717.1

2008-09 733.5

2009-10 778.6

3,298 7,292 449 5472 13,246 2010-11 818.8

2011-12 883.63

2012-13 917.8

Basis: * (GrossGen.+ Net Import) / mid-year Population

Ref.India:Power Sector Report (Feb 2014) - CEA, GoI;Others: World Bank Data

2.4.0 Pumped Storage Hydro

Pumped storage provides vital support to the national or regional electricity grid(s), helping to balance the flow of power across transmission networks by absorbing excess when electricity demand is low and releasing it when demand increases. With an ability to respond almost instantaneously to changes in the amount of electricity running through the grid, pumped storage is an essential component of the nation’s electricity network. Pumped storage is a proven grid-scale energy storage technology that can also enable India to grow its renewable energy portfolio. Moreover, the impact of construction of such projects on the environment is quite low. There is hardly any impact on flora and fauna.

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3.0.0 The Project, Site Visit & high level Reconnaissance, Initial Investigations 3.1.0 Project Inception

In the year 1979, Central Electricity Authority (CEA), Government of India (GoI), initiated the scheme of Purulia Pumped Storage Hydel, by way of preparing an assessment report. This was followed up West Bengal State Electricity Board (WBSEB), thru’ conducting a reconnaissance survey and preparing a project profile, based on four streams/ nullah on Ayodhya Hills in Purulia Dist. of W. Bengal State – Kistobazar, Turga, Kathlajal, and Bandhunala. Development Consultants Private Limited (DCPL), an India based consulting engineering firm, was then commissioned by WBSEB to prepare a Pre-feasibility report (in association with Harza Engineering, Chicago, USA), and instructed to submit the report in early January 1980, for onward submission to GoI, for funding.

Subsequently, DCPL had been instructed to carry out topographic survey, geotechnical and hydrological investigations and studies. This was supplemented by the state irrigation and waterways directorate for hydrological observation work in 1982. The project had been held up for several years in want of fund and decisions for investment.

3.2.0 The Project

Purulia Pumped Storage project is located in Baghmundi Village on

Ayodhya Hills under the district of Purulia, West Bengal, on Kistobajar Nullah /

stream(a tributary of Shaba nullah that drains into Subarnarekha River).

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3.3.0 Survey, Investigation, Desk Studies, Design & Engineering

For good engineering practice and statutory requirements (CWC and CEA, GoI), the following field survey & investigation works, desk studies, designs, cost estimates, etc. had been carried out, for preparing/ submitting the report:

Site Visit, High level Reconnaissance Survey & Invetigation (approach to site / availability & adequacy of roads & rail links; nearby towns, bank, post office, market; topographic, hydrologic incl. river/ stream regimes, geologic, soil/rock characteristics, flora & fauna, wild life, and catchment area visualization – survey & initial Investigations);– one week duration, by a team of engineers & scientists in the disciplines of civil engineering, applied geology, hydrology/ water resource engineering, hydro project expert; and, led by the Technical Director of the consultant;

Hydrologic Studies & Water Availability (based on Survey of India Topo - graphic Sheets, Field Data & Historical Data from Water Resources Dept (GoWB), Meteorological Data, Soil & Geologic characteristics at site);

Geo-technical Studies; Power Potential Studies (with 90% and 75% dependability on water

availability assessment); Evaluation of Reservoir Volumes & Water Levels;

Sedimentation Studies and Remedial Measures; Assessment & Preliminary Designs of upper & lower Reservoirs and

Dams; Intake Structures & gates; Penstocks & Tail Race Tunnels; Surge Tank(s); Power House: Hydro-Mechanical Equipment; Transmission lines/ Switch yard; Telecommunication system;

Assessment and Specifying Hydro-Mechanical and Electrical Equip-ment and ancillaries;

Construction Materials/ Quarries; Site Infrastructures and Construction Enabling Works; Project Implementation Plan, Program/ Schedules; Cost Estimate (local & foreign; applicable taxes, duties & levies); Cost-Benefit Analysis; and, Commercial Viability; Requirement of Essential/ Detailed Field Survey & Investigation works,

to be taken up in the next stage, like – Detailed topographical survey of reservoir area, project area, township,

roads & approaches; Survey of India Topographic Sheets; Procurement of satellite imageries

including aerial maps; Geo-physical surveys comprising seismic and resistivity tests, etc; Hydro-meteorological observations; Geo-technical exploration comprising surface mapping, drilling, drifting

and their logging; Laboratory Tests; Collection of Silt data & its analysis; Construction material survey- quantitative and qualitative;

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NOTE:

An over estimate of water availability may lead to larger investment and project

may become costlier resulting in a higher installation. On the other hand, a lower

estimate of water availability may result in a wastage of some hydro potential and

non- utilization of selected site optimally. Hydrological studies include assessment

of quantities of available water at the project site and time variation, estimation.

Planning of Hydro Projects is carried out based on 90% dependability

criteria. For determination of 90% dependable year, the total energy generation in

all the years for which hydrological data is available (say, N year) is arranged in

descending order and the (N+1) x 0.9 th year would represent the 90 per cent

dependable year. The 90 per cent dependable year is thus, termed as the year in

which the annual generation has the probability of being equal to or exceed 90 per

cent of the time on annual basis during the expected period of operation of the

scheme.For example, if inflow data is available for a period of 20 years (N=20),

then, 90% Dependable year = (20+1)*0.9= 18.9 = 19th year

Power Potential studies had been carried out for assessment of available Power

Potential of the stream based on a set of inflows and available head conditions

under various operating policies. (Such studies play an important role in the

optimization and design of new hydro facilities. They are used for examination of

various configurations and their integration into existing networks)s.

The detailed investigation was taken up

under loan assistance of 629 Million Yen

from Overseas Economic Co-operation

Fund, Japan and through Electric Power

Development Corporation, Japan, as

foreign consultant along with Central

Electricity Authority, Central Water

Commission; and, Water &Power

Consultancy Services) as local consultants.

The detailed project report was submitted

to CEA by WBSEB in 1992. The techno

economic clearance was accorded by

CEA in 1992. In February 1994, clearance

from the Ministry of Forest and

Environment (MoEF) received.

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In case of Pumped Storage Hydro Plants, however, the capacity of upper/lower reservoirs, availability of surplus off-peak energy, intended operating pattern of the pumped storage scheme determines its installed capacity. The procedure for optimization of the installed capacity and deciding the number of units is same as applied for run-of-river schemes/ storage based schemes.

The units size had been determined depending upon transportation constraints,

flexibility of operation and system considerations and geological constraints like permissible cavern size (underground power house, in this project).

4.0.0 Project Components – Sizing & Layout

Installed capacity 900 MW (4 x 225)

Peak operation duration 6 hours

Maximum power discharge 600 cum/sec

Effective head 177 m

Upstream reservoir

Catchment area 9.50 sqkm

Full reservoir level (FRL) 516 m

Minimum draw down level (MDDL) 494 m

** Dam height from rock foundation 71 m

Dam crest length 1.50 km

Reservoir area at FRL 1.00 sqkm

Total storage capacity 16.50 mil. cum

(a) Live storage 13.00 mil. cum

(b) Dead storage 3.50 mil. cum

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Downstream reservoir

Catchment area 9.50 sqkm

Full reservoir level 337 m

Minimum draw down level 300 m

** Dam height from rock foundation 95 m

Dam crest length 310 m

Reservoir area at FRL 0.53 sqkm

Total storage capacity 16.00 mil cum

(a) Live storage 13.00 mil cum

(b) Dead storage 3.00 mil. cum

Headrace intake tunnel 7.7 m diameter x 2

Penstock 7.7 - 7.3 m diameter x 2

4.3 m x 4

Tailrace 8.7 m diameter x 2

5.6m diameter x 4

Sedimentation rate 950m3 per ha/year

Powerhouse: underground powerhouse – 157 x 22.5 x 47.7 m (size), housing 4-vertical shaft, Francis reversible turbine-generator units of 225MW each.

Pump/ Turbine 230MW/250MW x 4, Francis

type

Reversible pump turbine, 250rpm

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Generator/motor 250MVA/255MW x 4,

Synchronous, 3 phase,

50Hz, pf. 0.9/1.0, 24 poles

Unit space 25.5m

Transformer capacity 280MVA, 16.5kV/400kV

Generation voltage 16.5kV

Transmission voltage 400kV

Construction cost (latest approved cost) Approx. US$665M

** Rockfill dams with central clay-core;

++ Two 400 kV double circuit transmission lines connecting Durgapur and

Arambag 400 KV S/S with PPSP have been constructed for transmitting/ receiving

power from PPSP.

5.0.0 Project Development and Economics

5.1.0 Project Development

In February 1994, clearance from the Ministry of Forest and Environment (MoEF), Government of India, had been received. 5.2.0 Economics

Pumping requires more power than the power that the same quantity of water can generate. Why then, we recommend installing pump storage hydro stations? The reasons can be attributed to: Make use of the difference between power pricing during peak & off peak

hours; Generally, the peak hour power price is higher than the off-peak;

The pumped water is used to produce power in the peak (evening) when it is costly. This helps to meet the extra power demand in eve.

Stabilize power distribution system for smooth running of industrial units

Improves the poor thermal-hydel mix ratio of the region to a great extent

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5.3.0 Project Benefits

Peak demand can be met instantly

Plant load factor of thermal power stations can be improved

Results in grid frequency stabilization of the region

Utilizes surplus grid power to pump water from lower reservoir to upper one at lean hours

Environmental Impact is Low

But, current market structures and regulatory frameworks in developing

countries, however, do not present an effective means of achieving this

goal. Policy changes and stream-lined licensing process are needed to

support the timely development of additional grid-scale energy storage.

A California Public Utilities Commission (CPUC) study (2010) identifies the following factors that contribute to economic development through the use of pumped storage technology: a) reduced need for peak generation capacity; b) employment and other economic growth; c) reliable and cleaner back-up power; d) transmission support and congestion relief; e) more efficient use of renewable and off-peak generation capacity; f) Reduced need for transmission and distribution capacity upgrades; and, g) Increased and improved availability of ancillary services.

The hydroelectric plants in the Columbia River basin in the Pacific Northwest generate 22,000 MW in output. In the photo: a dam wall in the many-branched dam system. (Credit: Fraunhofer IOSB)

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5.4.0 Further Initiatives by the State Utility

The State utility – WBSEDCL - has planned a detailed survey and project report for Turga Pumped Storage project (1,000 MW) and Bandhu Pumped Storage project (900 MW) in Purulia District. Detail Project Report (DPR) for both the schemes are likely to be completed by the fiscal: 2015 -16.

6.0.0 Policies, Regulatory Framework and Pricing Model

Policy till date has only articulated the objectives of peak demand being

met and spinning reserves created, but (unlike for baseload generation)

not the mechanisms to build or procure peaking power.

Peaking Power projects must be specifically identified. Trying to meet

peaking power needs from base load projects is bad economics, even if

optically cheap

Peaking Power must be an integral part of the perspective plans and the

five year planning process.

7.0.0 WAY TO GO:

A comprehensive Clean Energy Portfolio Obligation (CEPO) for utilities and users that combines Renewable Portfolio Obligations (RPO) to ensure renewable energy development; with,

Capacity Portfolio Obligations (CPO) to ensure that demand and supply

are balanced and peaking demand is served; and,

Energy Efficiency Portfolio Obligations (EEPO) - to ensure that utilities do the needful on energy efficiency and demand side management as well.

8.0.0 Acknowledgement:

Renewable Energy World Conference & Expo North America 2014

Central Electricity Authority (CEA), Government of India – Min. of Power

Planning Commission, Government of India

Geological Survey of India/ Survey of India/ I&W Dept (GoWB)

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WBSEB/ WBSEDCL/ NHPC/ ALSTOM

Foundation of Infrastructure Research Studies Training

Water Power and Dam Construction magazine

EPRI, 2002. Handbook for Energy Storage for Transmission or

Distribution Applications. Report No. 1007189. Technical Update

December 2002.

CPUC, 2010. Electric Energy Storage: An Assessment of Potential

Barriers and Opportunities. A Policy and Planning Division White Paper of

the California Public Utilities Commission.

Schoenung, S., M., & Hassenzahn, W., V., 2002. Long- vs Short-Term

Energy Storage Technology Analysis: A life cycle cost study

Taylor, R. (2007), Hydropower Potentials, International Hydropower Assoc

National Hydropower Association (NHA)

Anish De : AF-Mercados EMI - Peaking Power – Imperatives for the Indian

Power System

Development Consultants, India; The Kuljian Corporation, USA

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