POWER July 2011 - 73

ELECTRIC POWER 2011: WHERE THE GENCOS MEET
Sunny Days Ahead for Solar
In the U.S., developers of thermal and photovoltaic solar plants face a number
of challenges in their efforts to deploy more utility-scale solar power.
Some trends, however, are helping solar proponents move this renewable
energy source closer to becoming a mainstream generating option.
By Angela Neville, JD
F
rom new technical innovations to the
latest business developments, panelists
at the ELECTRIC POWER session on
" Solar Power and Photovoltaics " offered a
variety of perspectives about the new directions
that this energy source is taking in the
U.S. (Figure 1).
Trends in Utility PV Plants
In his presentation, " PV in the Utility Generation
Mix, " E.L. " Mick " McDaniel, senior
director of utility sales with Suntech America
Inc., focused on the growth of photovoltaic
(PV) solar plants.
" Approximately 1.9 GW of large-scale
PV solar projects are now under construction
in North America, " he said. " Twelve plants
larger than 50 MW have been completed
within the last 12 months. "
Utility solar development is shifting
to the U.S., according to McDaniel. Emphasizing
the growing momentum of PV
projects in North America, he pointed out
that the largest PV plant in the world, a 92MW
facility, came online last year in Ontario.
In addition, he said that construction
is under way on 10 plants that each will
generate more than 100 MW of electricity.
Meanwhile, " the PV pipeline currently has
over 22 GW of projects. "
McDaniel also pointed to statistics that
show the U.S. PV market is experiencing
strong growth. For example, in 2010, U.S.
utilities had 242 MW of PV solar energy capacity.
In contrast, by 2014, American utilities
are projected to have approximately
2,508 MW of PV capacity.
McDaniel talked about the impact of market
drivers on the U.S. solar sector. He first
focused on policies that are having a positive
effect on the growth of the solar market:
■
■
■
State renewable portfolio standards
Federal tax credits/cash grants
State tax credits and/or renewable energy
credit programs
Then he focused on the stimulative effects
on the solar market from " cost progress "
drivers:
July 2011 | POWER
■ Declining system costs
■ Declining development costs
■ Increased speed of execution
■ Lower cost of capital
Finally, McDaniel discussed how PV solar
projects are moving along at a much faster
rate than concentrated solar power (CSP, also
known as thermal solar) projects. He provided
the following current U.S. statistics:
■
■
■
538 PV solar projects and 518 CSP projects
have been completed.
1,008 PV solar projects and 870 CSP projects
are under construction.
21,000 PV solar projects and 8,060 CSP
projects are under development.
Water System Design for Thermal
Solar Plants
Daniel Sampson, senior technical consultant
with Worley Parsons, emphasized the need to
rethink the traditional water balance in thermal
solar power plants in his paper, " Key Concepts
in Thermal Solar Plant Water Systems Design. "
The operation and design of thermal solar
power plants differs substantially from that
of fossil fuel plants. The sun, rather than markets,
determines the maximum possible plant
dispatch, explained Sampson.
" Ideal plant locations seldom include
abundant or readily available water, " he said.
" The design of the power island is completely
different from that of fossil plants, yet designers
of thermal solar plant water systems
often use the same principles and approaches
common in their fossil plant cousins. This
renewable technology requires fresh thinking
in terms of water systems design. "
Unlike fossil plants, thermal solar plant
operators can predict plant starts and stops
to the minute. Water requirements, especially
for the steam cycle, can be predicted with
much more certainty than the water requirements
of variable-dispatch fossil plants.
Predictability may improve, but unique
challenges remain:
■
Solar mirrors must be cleaned, so demineralized
water usage increases.
www.powermag.com
■
Permits often require complete or partialzero-liquid
discharge, but this complicated
equipment requires a substantial commitment
in capital and manpower.
■
Plant water supplies may be of poor quality,
limited availability, difficult accessibility,
and high cost.
Water system design is always a balancing
act, and that's especially true for thermal solar
plants. Their unique design and operating
profile present both opportunities and challenges.
Water quality and quantity must be
evaluated carefully, and treatment processes
must be designed around the unique thermal
solar operating constraints. Simple designs
are best, Sampson advised, because operating
cost and operator involvement are usually
lower with simple designs. That's true of pretreatment,
demineralization, and wastewater
treatment systems.
New technology can provide benefits, but
only after very careful consideration and risk
mitigation. New approaches, nonetheless,
must be used. In many cases, the tools don't
change, but they're used differently and for
different purposes. ■
-Angela Neville, JD, is POWER's
senior editor.
73
1. Red-hot solar session. Members
of the session panel were (left to right): E.L.
" Mick " McDaniel, senior director of utility
sales with Suntech America Inc.; Daniel Sampson,
senior technical consultant with Worley
Parsons; Brian Friend, technical director, Doosan
Power Systems; and Brian Robertson,
chief executive officer of Amonix Inc. Cochairs
were Vas Choudhry, a California-based consulting
engineer with many years of experience in
the electric utility industry, and Angela Neville,
JD, senior editor of POWER. Source: POWER
http://www.powermag.com
POWER July 2011

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