The Hydro Resource and Micro Hydroelectricity Systems
The Solar Resource
Overview
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•
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Review of the Hydrologic Cycle
System components
Measuring head and flow
Generating power from water (examples)
6/22/2009
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Hydrologic Cycle
• Key terminology
» Insolation
» Evaporation
» Transpiration
» Evapotranspiration
» Sublimation
» Condensation
» Precipitation
» Infiltration
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» Sub-surface flow
» Ground water
discharge
» Overland (surficial)
flow
» Freshwater storage
» Oceanic storage
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Hydrologic Cycle
Insolation
condensation
sublimation
Precipitation
Transpiration
Surficial
flow
Freshwater
storage
Oceanic storage
Infiltration
Subsurface flow
6/22/2009
Evaporation
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Groundwater
discharge
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Hydro Power
• For most hydro systems, we are interested in
only certain processes in this cycle
» Oceanic storage (wave, tidal, ocean current)
» Freshwater storage (wave, pumped storage, dams)
» Overland flow (streams and rivers)
• Though our systems use these processes, we
must keep in mind that it is a cycle
» Water is replenished in our systems due to
incoming solar energy
6/22/2009
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Measuring the hydro resource
In central New York, when do we get most of our
precipitation?
MSC mean rainfall (2003-2008)
Inches of Rainfall
5
28 inches per year
4
3
2
1
0
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Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
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Measuring the hydro resource
1500
Mean
2006
1000
500
Au
gu
Se
st
pt
em
be
r
O
ct
ob
er
No
ve
m
De be
r
ce
m
be
r
Ju
ly
Ju
ne
ay
M
Ap
ril
0
Ja
nu
ar
y
Fa
br
ua
ry
M
ar
ch
Cubic Feet per Second
Chenango River Discharge
http://waterdata.usgs.gov/nwis/
6/22/2009
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6/22/2009
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System components: Intake
• Water enters penstock
through the intake
• Remove debris
• High maintenance
• Accessible
6/22/2009
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System components: Penstock
• PVC
» Cheap, light, and rigid
» Low pressure systems
» Easily available at
hardware stores
» Low losses (in straight
sections)
» Freezing issues
6/22/2009
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System components: Penstock
• Polyethylene tube
» Flexible
» Longer lengths
» Lower losses in sweeping bends
» Freeze resistant
» Expensive components
» Difficult to purchase
6/22/2009
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System components: Turbine
• High head, low flow
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•
•
•
6/22/2009
1, 2, and 4 nozzle designs
12, 24, 48, VDC options
120 VAC options
Pelton wheel with bronze
runner
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System components: Batteries
•
•
•
•
Lead-acid
Deep cycle
Generally 2 to 6V
Wet cell or sealed (gel)
6/22/2009
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System components: Charge controller
• Monitors battery bank voltage
• When the battery bank is “full”,
electrons are diverted to a
diversion load (a.k.a. dump
load)
• Can be jumped from 12,24,
and 48 VDC depending upon
input and battery bank (they
must match!)
6/22/2009
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System components: Diversion Load
• Waste electrons as quickly as possible
• Resistance heating elements
• Protect the battery bank
6/22/2009
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System components: Inverter
• Converts direct current (DC) to alternating
current (AC)
• Can match the utility signal (voltage, shape
and frequency)
6/22/2009
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Generating power
Now that you understand the system
components, how does one actually generate
power with a micro hydro system?
6/22/2009
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Measuring the hydroelectric resource
• Power generation from water is dependent on
five variables:
» P=ηρgQH
» Power in watts (P)
» Turbine efficiency (eta, η)
» Water density (rho, ρ; usually 1000 kg/m3)
» Acceleration of gravity (g, 9.81 m/s2)
» Quantity of water flow (Q, in m3/s)
» Vertical distance (head, H, in meters)
6/22/2009
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Measuring a stream – flow
Flow rate (Q)
• Quantity of water passing a given point over a
given amount of time
» Cubic meters per second
» Gallons per minute
» 1 GPM = 0.000063 m3/s
6/22/2009
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Measuring flow
6/22/2009
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Measuring the hydro resource - head
Head (H)
• Head is the vertical distance of the hydro
system (from intake to turbine)
• Relationship of head
and pressure
2.31 feet
1 psi
6/22/2009
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Measuring head
6/22/2009
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Stream profile diagram
1,110 feet of penstock
6/22/2009
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Hydro power - example
• Small stream:
» 20 GPM flow, 140 feet of head, 85% turbine
efficiency
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•
•
6/22/2009
Pressure:
 1 psi 
140 ft 
  60.6 psi
 2.31 ft 
Flow:
 0.000063 m 3 /s 
  0.00126 m 3 /s
20 GPM 
1 GPM


Head:
 0.305 m 
140 ft 
  42.7 m
 1 ft 
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Hydro power: example
• P= η ρ g Q H
» Power = 0.85*1000 kg/m3*9.81 m/s2*0.00126 m3/s *
42.7 m
» Power = 448.6 watts
• Yearly energy in kWh?
» 448.6 W *24 hrs/day * 365.25 days/yr = 3,932 kWh/yr
• My house uses about 4,000 kWh/yr
6/22/2009
http://retc.morrisville.edu
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Hydro power: what if?
• If we go from 20 GPM flow and 140 ft of head
to 140 GPM and 20 ft of head?
• What power (watts) should I expect?
• P= η ρ g Q H
» Power = 0.85*1000 kg/m3*9.81 m/s2*0.00882 m3/s *
6.1 m
» Power = 448.6 watts
6/22/2009
http://retc.morrisville.edu
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Hydro power
• Head and flow have equal importance in
determining power (and energy) in a hydro
system
» What we have just calculated does not take
penstock losses into account
» This will reduce power output
6/22/2009
http://retc.morrisville.edu
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Hydro power: a comparison
• 20 GPM and 140 ft of Head
• Yearly energy in kWh?
» 448.6 W *24 hrs/day * 365.25 days/yr = 3,932 kWh/yr
• My house uses about 4,000 kWh/yr
6/22/2009
http://retc.morrisville.edu
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6/22/2009
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…to wind!
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Class 3 site (7 m/s average; 15 mph)
Turbine at 30% efficiency
P=0.5* η ρ A V3
450 W = 0.5*0.3*1.2 kg/m3*(3.14*r2)*(7 m/s)3
r = 1.5 meters, diameter = 3 meters
This means to get an equivalent amount of
energy, I need a 10’ wind turbine rotor!
6/22/2009
http://retc.morrisville.edu
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So, what bother with micro hydro?
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•
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(Relatively) inexpensive
Constant power production (not intermittent)
Minimal impacts
Turbines have high efficiency (80% to 90+%)
Challenges
• Not considered “renewable and sustainable”
• Permitting process may be required
• Highly selective sites
• Currently cannot be net metered
• Little knowledge of our resource
6/22/2009
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Contact Information
Phil Hofmeyer, Ph.D.
Assistant Professor
Ph: 315-684-6515
Email: hofmeypv@morrisville.edu
Web: http://people.morrisville.edu/~hofmeypv/
Ben Ballard, Ph.D.
Director, RETC
Assistant Professor
Ph: 315-684-6780
Email: ballarbd@morrisville.edu
Web: http://people.morrisville.edu/~ballarbd/
http://retc.morrisville.edu