Research Questions

What is the role of Concentrated Solar Power (CSP) in meeting Arizona’s renewable energy requirements?

Are solar water requirements a critical limiting factor?

How does potential water use for CSP fit in the grand scheme of Arizona water supply & demand

How much water would be needed to meet AZ’s RPS using CSP?

AZ’s renewable portfolio standard (RPS) calls for 15% of electricity coming from renewable sources by 2025

10.5% from non-distributed systems

4.5% from distributed systems (PV will play a large role)

Assumptions

Take Black & Veatch (2007) renewable electricity demand projections to meet non-distributed RPS requirements

Assume 100% of this demand is met using CSP trough technology with closed-loop cooling

Use water requirement assumptions from DOE report to Congress (928 gallons / MWh)

Total Renewable Demand to Reach 12,000 GWh by 2025

Black & Veatch Total Renewable Energy Demand Projections

0

2000

4000

6000

8000

10000

12000

14000

2007 2009 2011 2013 2015 2017 2019 2021 2023 2025

GWh

Meeting RPS would require <35,000 acre feet of water

Acre feet of water required to meet Arizona's RPS using only CSP trough technology

-

5,000

10,000

15,000

20,000

25,000

30,000

35,000

2007 2009 2011 2013 2015 2017 2019 2021 2023 2025

AF o

f wat

er c

onsu

med

Placing potential CSP water use in context

How does it compare to agricultural water use?

How does it compare to statewide demands?

Water Use by Commercial Scale Farms

USDA uses different definitions of commercial farms

One is farms with >$250K in sales

I use a less restrictive cut-off of >$100K in sales

AZ commercial-scale farms (as I define them)

Had gross sales of >$100K

705 farms total from 2008 USDA Farm & Ranch Irrigation Survey

Accounted for 94% of agricultural water use:

>4.3 million Acre Feet (AF) of water applied in 2008

Smaller Scale Operations

Accounted for 6% of agricultural water use

Farming not their main source of income Farms in $50K – $99.9K range averaged

<$10K in net farm income Farms in $25K – $49.9 range averaged

<$4,750 in net farm income

So, how much water do commercial-scale irrigators apply?

Using my definition of commercial: 6,150 AF per farm per year

Using USDA >$250,000 in sales definition: 7,718 AF per farm per year

Potential Water Use from CSP in Commercial Farm Equivalents

Acre feet of water required to meet Arizona's RPS using CSP

-

6,150

12,300

18,450

24,600

30,750

36,900

2007 2009 2011 2013 2015 2017 2019 2021 2023 2025

AF

of w

ater

con

sum

ed

1 farm equivalent by 2013

2 farm equivalents by 2017

5 farm equivalents by 2024

Potential Water Use from CSP Miniscule Compared to Agriculture

CSP potential use <35,000 by 2025

Agricultural use: >4,300,000 in 2008

Point is not to pick on agriculture

Quite the contrary

Few would argue that 4 or 5 farms (out of 705) impose an undue burden on state water resources

Just want to place numbers in perspective

How much is <35,000 AF in the context of AZ water use

According to 2006 Arizona Water Atlas, statewide demand was 6.86 million acre feet

How does 34,272 of water potentially used by CSP by 2025 compare to total demand?

CSP 2025 Solar water use would be 0.5% of current demand

Derived demand for water for CSP electricty production by 2025 as a share of water diverted, pumped from wells, or

received to meet demand in Arizona

99.50%0.5%

SolarAll Other

Potential 2025 CSP Water Use Compared to 2006 AZ Water Demands

Solar

Municipal

Industrial

Agricultural

Based on AZ Water Atlas water demand data

How much is ½ of 1%?

1 teaspoon = 0.4928% of a Liter

So, if Arizona’s current water use were represented by a 2 Liter bottle of water, CSP water use would only reach 2 teaspoons by 2025

Black & Veatch projected solar’sshare of Arizona’sRenewable energy would reach 65%By 2025

That translates into22,277 AF by 2025

The water use of 3-4 commercial farms

What is 65% of 0.5%?

If Arizona’s water use were represented by the calories in a Big Mac . . .

. . . solar’s water use assuming 65% of renewable electricity generation would be fewer calories than the lettuce in the Big Mac

22,277 AF by 2025

Q: How much water would you save in 2025 if nuclear energy supplied this amount of electricity?

A: <11,000 AF0.16%

(calories of about half of the lettuce on that Big Mac)

Water embodied in AZ net electricity exports <30,000 AF

Source: Pasqualetti & Kelly

Water embodied in AZ exports

Whest

Cotton

0

250,000

500,000

750,000

Electricity Whest & Cotton

Acre

Fee

t

Water embodied in AZ exports

Whest

Cotton

0

250,000

500,000

750,000

Electricity Whest & Cotton

Acre

Fee

t

Electricity exports are exports out of state, while agricultural exports are exports out of country

Water embodied in AZ exports

Wheat

Cotton

0

250,000

500,000

750,000

Electricity Whest & Cotton

Acre

Fee

t

Water embodied in electricity exports are 4% of water embodied in cotton and wheat exports

Land Use Issues (quickly)

Development applications are not the same as development

Critical to have realistic projections of future electricity demand and derived water and land demand

Oil rigs at Huntington Beach

Active leases for drilling oil & gas

There are not offshore platforms everywhere there are leases

Summing UpThese back of the envelope calculations picked the most water-using CSP technology Water use would be less assuming different

technologies Did not account for innovations over 15 years

Important to have realistic demand projections in context of overall supply & demand

Important to consider net water use of alternative energy sources

Summing UpEconomists usually favor use of market mechanisms and price signals to allocate scarce resources

Past experience has shown that command-and-control approaches focusing on technology standards are highly inefficient

Summing UpSolar energy will not be a burden

Arizona’s water resources in the foreseeable future

Although, as with any economic activity (e.g. electricity generation by any source), the local environmental effects need to be considered

Questions

George FrisvoldProfessor & Extension SpecialistDepartment of Agricultural & Resource EconomicsUniversity of Arizonafrisvold@ag.arizona.edu(520) 621-6269