Panel cooling and suspension support structures present opportunities for reductions in life cycle greenhouse gas payback periods Water Savings Shading may reduce evaporation by approximately 80% but additional experiments are needed to inform design and reduce uncertainties. Deploying the AquaGrid on canals with 100 foot wide water surfaces could reduce annual evaporation by 30 to 90 acre-feet per mile of canals. An additional savings of 23 to 79 acre-feet per mile would result from using solar energy to offset more water intensive forms of electricity production. Cost Analysis Compounding advantages of the Solar AquaGrid with tensioned cable systems have the potential for large economic advantages Water Rights rights in California are administered by the State Water Resources Control Board Central Valley Project has long-term contracts with over 250 contractors in 29 counties State Water Project delivers water to State Water Project Contractors consisting of 27 public agencies Aqueduct Most major canals are generally concrete-lined canals, with maintenance roads on each side of the canal Maintenance accessibility should be a key design consideration Water and Electricity Forecasts California water prices are projected to increase by 20% by 2050 California electricity prices are projected to increase by 50% by 2050 Future research incorporating climate change and water resource models may show larger escalations Site Evaluation Sites considered: Devil’s Den Pumping Plant, Edmonston Pumping Plant, Pleasant Valley Pumping Plant, Dos Amigos Pumping Plant, University of California Merced campus, Rancho Seco Pumping Plant, Colusa County Water District 2B, and the Williams Wastewater Treatment Plant Devil’s Den, Edmonston, and Pleasant Valley Pumping Plant scored highest in a multi-criteria site selection analysis Sites with high potential for visibility are the Williams Wastewater Treatment Plant, Dos Amigos Pumping Plant and University of California Merced campus Life cycle analysis indicates that greenhouse gas payback periods are as low as 2 years when offsetting the current California energy mix. Lower payback periods are possible for offsetting diesel-powered irrigation pumps that may be adjacent to some Solar AquaGrids. Considering an increased efficiency from panels being cooled by conveyed water, the payback period can be further reduced by 3 months. Adding a truss support structure into the life cycle analysis increases the payback period by nearly 1.5 years. Novel support structure designs (e.g. suspension structures) may be able to reduce the impact of support structures on greenhouse gas payback by up to 50%. Water Savings
Table 2.2: Overview and comparison of concentrated solar power (CSP) technologies taken from (Khan and Arsalan, 2016). Technology Parabolic troughs Linear Fresnel reflectors Solar towers Parabolic dish (Dish-Stirling) How it works? By focusing the parabolic sheet to a fixed point where objects intended to be heated are placed, It can be single axis or dual axis (for tracking of the sun) The Long and thin segment of mirrors are used to focus incoming rays to the fixed absorber then concentrated heat goes to a heat exchanger to drive steam generator The larger number of heliostats are used for focusing sun rays onto a central receiver then the heated such as molten salt is used to produce steam for electricity generation It uses mirrored dishes to concentrate sunlight onto a central receiver and then the converted thermal energy can be used to produce electricity or it can also be routed to the main grid Capacity (MW) 10–300 10–200 10–200 0.01–0.025 Commercially mature or not? It has been commercially proven projects Pilot commercial projects Demonstration projects efficiency in % (Annual) 11–16 13 7–20 12–25 Temperatures (°C) 350–550 390 250–565 550–750 Storage systems exist? Yes Yes Yes No Advantages •Most mature CSP technology •It can produce heat at higher temperatures •Higher concentration •Cheaper than parabolic trough collectors •Increased efficiency •Generate electricity in absence of sun •Economically proven •Higher efficiencies •The most efficient systems Disadvantages •Output restricted to moderate steam •Less efficient •Difficult to integrate storage capacity into design •Requires a large area of land •Daily maintenance •High cost •Lack of flexibility •Heat transfer require a number of equipment
Modules 678,259 Inverter 149,616 Module support 159,590 Balance of system equipment 179,539 Installation labor 189,513 Installer margin and overhead 159,590 Contingency $ 60,644 $ $ Subtotal Direct Costs 1,576,752 Permitting 29,923 Environmental studies 29,923 Engineering and developer overhead 299,232 Grid interconnection 49,872 Land costs 29,923 Land preparation and transmission 29,923 $ $ $ $ $ $ $ $ $ 5 3 4 5 6 8 . . . . . . . 32 W W W W W 0 0 0 0 0 59 59 32 0 / / / / /
Appendix B Table 1 of 4 Contractor Direct Pumping Other PUE Remittance Contract Rate O&M Cost of Service Rate Butte D&R County of Colusa 26.96 26.27 26.96 Elk CSD 26.27 26.27 26.27 U.S. Forest Service 30.09 26.27 30.09 Whitney Const. 34.99 26.27 34.99 Clear Creek Unit Clear Creek CSD 26.27 26.27 26.27 Contra Canal Contra Costa WD 11.17 1.43 25.82 25.82 25.82 Cow Creek Unit Bella Vista WD 42.19 42.19 42.19 Cross Valley Canal County of Fresno 109.73 36.66 109.73 County of Tulare 140.55 36.66 140.55 Delta-Mendota Canal Bethany ID 26.41 26.27 26.41 City of 33.19 26.27 33.19 Del Puerto WD 26.27 26.27 26.27 Department of Veterans Affairs 51.16 26.27 51.16 Panoche WD - DMC 26.34 26.27 26.34 San Luis WD -DMC 26.27 26.27 26.27 Appendix B Table 2 of 4 Contractor Direct Pumping Other PUE Remittance Contract Rate O&M Cost of Service Rate