Do the Math

Can Someone Please Do the Math

Calera Creek Photovoltaic System

300 Kw AC peak power
$3,100,000 Capital Cost / $1,800,000 after rebates
($10/peak Kw or $6/kw after rebates)
4.4 hours per day year around average production at peak power (18% plant availability factor)
(5.1 hrs in summer, 3.7 hrs in winter)

280,000 kw-hr May to October
200,000 kw-hr November to April

Time	Power Cost*, $/Kw-hr	PV Production, Kw-hr	PV Savings
Summer Peak	0.14	140,000	$19,600
Summer Half Peak	0.13	140,000	18,200
Summer Off Peak	0.09	0	0
Winter Peak	0.10	100,000	10,000
Winter Half Peak	0.10	100,000	10,000
Winter Off Peak	0.09	0	0
Totals		480,000	$57,800

* PG&E Commercial Time of Use Rate A-10 (Best rate for users of more than 50,000 kw-hr)

$3,100,000 / 57,800 = 54 years payback (with a zero interest rate loan from your Grandma)

$1,800,000 / 57,800 = 31 years payback (with a zero interest rate loan from your Grandma and a $1.3M gift from your other Grandma)

BioDiesel for the Emergency Diesel Generators at the Caldera Water Treatment Plant

100% conversion factor for btu to kw-hr : 3,413 btu/kw-hr
Diesel Engine Efficiency: 20-40%

Energy content of Diesel Fuel: 140,000 btu/gal = 8-16 kw-hr/gal
Energy Content of B20 BioDiesel: 138,000 btu/gal = 8-16
Energy Content of BioDiesel: 120,000 btu/gal = 7-14

Claim in Pacifica Tribune 7/25/2007: 60,000 kw-hr / 3200 gal fuel (diesel, b20, b100?)
                                                          per month
                                                          18.8 kw-hr/gal or 46, 46, or 53% overall electrical
                                                           efficiency
                                                          $9,000 ($0.15/kw-hr) per month savings or
                                                          $25,000 ($0.42/kw-hr) if peak savings.
                                                          $44,000 for co-generation engine (lease?)

Last Revised 07/26/2007