Mar-11. Oct-11. Dec-12. Aug-13 Jul-14 Apr-15. Mar-16. Aug-16. Jan-17. 0. 20,000. 40,000. 60,000. 80,000. 100,000. 120,00
FRIENDS OF THE EEL RIVER: INITIAL FEASIBILITY EVALUATION (Feb-2017) FOR REPLACING POTTER-VALLEY HYDROPOWER WITH SOLAR ENERGY John Rosenblum, PhD (707) 824-8070
[email protected]
CONCLUSIONS 1. Feasible to replace hydropower with solar+batteries within Ukiah’s city limits: I. 3 acres of solar photovoltaics (13 MW rated) on parking lots II. 27 MWh battery storage (max; not optimized) III. $40 million installed cost 2. Cost of solar could be justified by comparing with PVP upgrades 3. Replacement costs can be reduced by combining solar systems with: i. ii. iii.
End-use load reduction (efficiency) Non-battery end-use storage (load shifting) Wind power
ANNUAL RELEASES 400,000
Mendocino PVP 350,000
EB Russian (approximate w/o irrigation withdrawals)
300,000
Releases from Lake Mendocino are larger than the approximate inflows from the East branch of the Russian River (minus the withdrawals by irrigation districts). The additional water is from PVP releases from the Eel River.
AF/yr
250,000
200,000
150,000
100,000
50,000
0
2005
2006
2007
2008
2009
2010
2011
2012
2013
2014
2015
2016
MONTHLY RELEASES 120,000
PVP Mendocino 100,000
AF/month
80,000
60,000
Mar-11 Jan-17
40,000
Mar-16
Dec-12
20,000
Oct-11 Aug-16 Aug-13
0
Jul-14 Apr-15
Largest releases from Lake Mendocino are in winter for flood control, but there are also smaller summer peaks for Russian River water supply
MENDOCINO HOURLY RELEASE FLOWRATES 3,500
3,000
2,500
Jan-11 Jan-12
2,000
cfs
Jan-13 Jan-14 Jan-18
1,500
Jan-19 1,000
500
0 0
1
2
3
4
5
6
7
8
9
10
11
12
13
Hour of Day
14
15
16
17
18
19
20
21
22
23
Releases from Lake Mendocino are almost always constant over a 24hour period, but when storms occur, the flows are ramped up/down over 6-8 hours The ramps up/down also change the power output of the turbines
HYDRO-ENERGY 70,000
100%
PVP Mendocino 60,000
The hydropower plants (PVP and Lake Mendocino) have been operating at less than 50% of full capacity for many years.
90%
TOTAL avg.CAPACITY (PVP+Mendocino)
80%
50,000
70%
60%
50%
30,000 40%
30%
20,000
20% 10,000
10%
12% 0
0%
2005
2006
2007
2008
2009
2010
2011
2012
2013
2014
2015
2016
Capacity
MWh/yr
40,000
55%
Hydropower is extremely variable, and in recent years has been trending down.
Daily flow from Mendocino is almost always constant over a 24-hr period (previous graph). Power output was estimated from total turbine rating (3.5 MW), between min/max limits for daily flow (104400 cfs) and head (28-73 ft). The operation of each turbine (2.5 MW and 1 MW) was not known.
Only daily flow data was available for PVP, and it was assumed that it is constant over a 24-hour period. Power output was estimated from total turbine rating (9 MW), between min/max limits for flow. (70-270 cfs) The actual operation of the turbines was not known.
HYDRO-ENERGY 9000 PVP Mendocino TOTAL
8000
7000
MWh/month
6000
5000
Jun-16
4000
3000
Jul-14 Apr-15 2000
1000
0
Hydropower is extremely variable, and in recent years is often zero in winter (when solar would also be low). This implies that local demands require grid supply – and are not dependent on hydro. PVP releases are highest in summer when Eel River needs are highest. This is exactly when solar PV would also be highest and could easily displace hydro. Ukiah’s hydropower from Lake Mendocino has actually only been in operation since 2007, and is even more variable than PVP – with longer periods of zero production because the reservoir is too low. Summer hydro could be easily displaced by solar PV.
SOLAR ELECTRICAL POWER OUTPUT (January 2011)
SOLAR ELECTRICAL POWER OUTPUT (August 2011)
600
600 kWmax
kWmax
kWavg
kWavg
500
500 kWmin
kWmin
400
kW
kW
400
300
300
200
200
100
100
0
0
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
0
1
2
3
Hour of Day
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
Hour of Day
Based on performance data from a large (1 MW nameplate rating) in Mendocino County along the 101 corridor. Power output varies between seasons/months, and with the hour of day. The differences between min/avg/max are driven by weather/clouds.
January avg operation is 8 hrs/day; August is 11 hrs/day Energy (kWh) = Daily sum of [Power (kW)] x [Operation (hrs/day]
21
22
23
ANNUAL SOLAR PV OUTPUT (per unit of nameplate power) 90%
140
Based on performance data from a large (1 MW nameplate rating; 2011), and a small (5.5 kW nameplate rating; 2016) in Mendocino County along the 101 corridor.
80% 120
70% 100
80
% Wp
50%
40%
60
30% 40 20%
Avg Monthly Energy per Unit of Nameplate Power (Wp) 10%
20
Max Fraction of Nameplate Power (Wp) Avg Fraction of Nameplate Power (Wp)
0%
0
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
Wh/month/Wp
60%
Max power occurs near noon (depending on collectors’ azimuth and tilt angles) on clearest day of each month. Avg power and energy calculated from the sum of daily hours of operation and energy output for the whole month (both depend on weather conditions and change from year to year).
SOLAR PV SURPLUS OR GRID IMPORTS 6,000
Aug-15 4,000
Aug-16 2,000
MWh/month
solar surplus
Since 2013, 4 acres of solar PV would mostly provide a surplus – except for large winter and spring releases
0
grid imports Mar-16 -2,000
Jun-16 Dec-16 -4,000
6 Acres -6,000
4 Acres 2 Acres
-8,000
with 6 acres of solar PV, there would always be surplus energy – except for large winter and spring releases (e.g. Mar-16; Dec-16)
Even 2 acres of solar PV could be sufficient when combined with wind, efficiency, and load shifting – but validation requires data about supply through 5 PG&E substations along the 101 corridor.
INSTALLED REPLACEMENT COST OF SOLAR
Installation priority (based on unit costs of PV and battery):
$120
Open Ground
1. Parking lots
Single Family Residences $100
2. Commercial buildings
Multi Family Residences 89,400 sq-ft (266 homes; 7% SFR) and 2.5 MWh battery
Commercial Bldgs
4. Single family residences
Parking Lots 184,800 sq-ft (27 8-unit complexes; 13% MFR units) and 5.1 MWh battery
$ million
$80
5. Open ground Optimal size is likely between 2-4 acres, depending on:
$60 642,300 sq-ft (8 buildings; 28%) and 17.6 MWh battery
$40
3. Multi family residences
Most likely cost $40 million (3 acres)
$20
264,800 sq-ft (3 buildings; 12%) and 9.0 MWh battery
Ability to reduce and reshape local demand patterns to match solar output 3.2 acres (21%) parking and 35.4 MWh battery
3.2 acres (21%) parking and 28.5 MWh battery
4
6
2.0 acres (13%) parking and 18.5 MWh battery
$0 2
PG&E substation demand patterns i.e. how much of the hydro is actually used locally
Acres Solar PV
Non-battery, end-use storage options such as chilled water/ice and irrigation reservoirs Allowance for non damaging releases in wet months
INSTALLED REPLACEMENT COST $120
Batteries were sized to replace hydro in non-solar hours, whenever a solar surplus was calculated from Jan-13 to Dec-16 data (maximum value selected).
Battery Cost PV cost $100
There are practical technical limits on the size/duration of batteries. Currently batteries are usually applied to bridge gaps created by clouds or other short-term interferences.
$ million
$80
$60
$40
This means that every effort should be made to reduce and shift loads with nonbattery, end-use storage options such as chilled water/ice and irrigation reservoirs
$20
$0 2
4
Acres Solar PV
6
SOLAR INSTALLATION COST AND ANNUAL NET REVENUE $110 Total Cost $100
Annual net revenue is the value of the solar energy at wholesale or retail electricity prices, plus any surpluses (more solar energy generated than provided by hydro) Surpluses are possible beyond 2 acres.
Wholesale Net Revenue ($million/yr) Retail Net Revenue ($million/yr)
$90
$80
At 2 acres, not enough solar energy is available to replace all the hydro. This means that electricity must be purchased from the grid to make up for the hydro, and the net revenue is smaller than for hydro.
$70
$ million
Installation cost is the capital required for the solar systems.
$60
$50
Net revenue from the solar will not provide a short-enough payback period to justify the investment within the expected 20 year lifetime for solar systems.
$40
$30
$20
$10 $0.52
$1.55
$1.04
$3.11
$4.66 $1.55
$0
2
4
Acres Solar PV
6
The hydro replacement could be justified by netting out PVP upgrade costs from the solar installation costs – and by adding the value of fisheries restoration.
2005-2016 DATA REQUIRED TO IMPROVE ACCURACY OF RESULTS 1. Hourly end-use demand in Ukiah (City and NCPA) – or PG&E substation data 2. Hourly flow data (E16) through the PVP diversion tunnel – or confirmation from PG&E that hourly flow is constant
3. Operations parameters for PVP turbines (PG&E or FERC): a. Max/Min limits of flow and power – and/or known correlations b. Daily energy generation 4. Operations parameters for Mendocino turbines (City of Ukiah, NCPA, or FERC):
a. Max/Min limits of flow, head, and power – and/or known correlations b. Daily energy generation 5. Confirmation of total number/area of urban facilities: parking lots, commercial buildings, MFR, SFR (City of Ukiah) 6. Hourly output data from 3-5 more existing solar systems, over 3-5 previous years (public agencies and schools)
CONCLUSIONS 1. Feasible to replace hydropower with solar+batteries within Ukiah’s city limits: I. 3 acres of solar PV (13 MW rated) on parking lots II. 27 MWh battery storage (max; not optimized) III. $40 million installed cost 2. Cost of solar could be justified by comparing with PVP upgrades 3. Replacement costs can be reduced by combining solar systems with: i. ii. iii.
End-use load reduction (efficiency) Non-battery end-use storage (load shifting) Wind power
