Solar Power Desalination
Here Comes the Sun: Taking Solar Power to Grid-Scale

By Lori Pottinger
World Rivers Review
March 25, 2008

What renewable energy source is highly reliable and predictable,
especially productive during the hours of highest electricity use, can be
scaled small enough to power one building or big enough to electrify a
town, is a proven technology whose costs keep dropping, creates more jobs
than gas or coal, and could, with a major rollout, displace 2-3 billion
tons of carbon annually worldwide?

The answer is concentrating solar power, which uses mirrors and the power
of the sun to run steam turbines. Unlike some other energy innovations
being put forth today - "clean coal," for example - there's no "smoke and
mirrors" trickery about it. Just mirrors. Lots and lots of mirrors.

This exciting renewable energy technology has been working reliably in
California since the 1980s, when oil was cheap and climate change was for
wonks. Today, the political and economic conditions that prevented a major
rollout of the technology are, pardon the pun, almost a mirror image of
the situation in the 1980s. Today, every indication is that concentrating
solar power (CSP) is on the cusp of a renaissance, thanks to increased
investments in R&D, tariff support for CSP plants' electricity in Spain,
and a growing realization among governments and financiers that the world
needs to build renewable energy sources now.

A line-concentrator solar power plant in the Mojave Desert, California.
(Warren Gretz)A surge of development in Spain and the US West is well
underway. Two new plants producing 65 megawatts of electricity have been
built in the US (adding to California's 355 MW of existing CSP), while
Spain has completed 10 MW, has 50 more projects in the pipeline, and
intends to develop 500 MW by 2010. The goal of the US National Renewable
Energy Lab (NREL) is to help develop up to 4,000 megawatts of CSP in the
southwestern US by 2015. "This penetration level is aggressive, but
possible if the 30% investment tax credit is extended per the primary
recommendation of the task force," says George Douglas, an NREL spokesman.

Elsewhere, plants are planned or being built in Egypt, South Africa,
Australia, Libya, Algeria, India, Israel and Morocco. And if a Jordanian
prince has his way, tens of thousands of megawatts would be generated in
the Sahara for sale to Europe. Renewable Energy World forecasts 6,400 MW
installed globally by 2015, leaping to 36,850 MW by 2025. By then, they
project an annual installation rate of 4,600 MW/year.

"After over a decade of inaction, CSP is finally taking off," says Sven
Teske with Greenpeace's Energy [R]evolution Campaign. "For 2040, CSP has a
chance to contribute to the global electricity supply in a double digit
range. The main reason for this is good policy. In the USA there are
Renewable Portfolio Standards in place, in Spain there are guaranteed tariffs."

How it Works

Dish Stirling solar power systems concentrate the sun’s heat to run a
Stirling engine, which drives an electric generator.CSP uses sun-tracking
mirrors to concentrate solar heat onto liquid-filled tubes or central
tower. The liquid is vaporized into steam, which is used to drive turbines
to generate electricity. CSP plants act much more like conventional power
plants than solar PV or wind farms, which make them more attractive to
utilities. There are a variety of types of plants being tested and built,
with different advantages to each. Because they are fairly simple to
design and build, the plants go up quickly. A new CSP plant near Las
Vegas, Nevada took about one year to build. (Permitting and land-use
acquisitions add to the process, however.)

CSP still has obstacles to overcome. Most importantly to utilities is its
still-high cost. While concentrated solar power is now less expensive than
solar PV panels, it is still generally around 15-20 cents/kwh, well above
fossil fuels and wind (though windpower is more "intermittent" than a
well-sited CSP plant, and generally wind's peak production time does not
match peak loads as well). Prices for CSP are coming down, however, and
the projected increase in new plants will help drive down prices further.
Most companies are shooting for a target contract price of 15 cents/khw in
the US, whereas "the price for electricity from new baseload natural gas
plants is about 9 cents per kilowatt hour, and rises to 12 to 48 cents/kwh
for peak power, depending on what report you read," says Tom Hunt, with
the Community Environmental Council. Unlike fossil fuel plants, which are
expected to see rising prices over time, CSP plants have no fuel costs,
and therefore no future price surprises once a contract is signed.

At least one company says they have already solved the cost issue. The
US-Australian company Ausra has a new proprietary design that it says can
produce electricity for 10 cents/kWh. Not only is Ausra's design cheaper;
the company will also save money by manufacturing units as close to where
they'll be installed as possible, to reduce shipping costs. Ausra is now
building the "world's largest" CSP factory in Nevada that will be able to
churn out 700MW/year in new systems, to supply the hot US Southwest
market. Other companies are also trimming the costs of their units by
incorporating lighter materials, fewer moving parts, and other innovations.

One factor that would allow CSP to compete on an equal playing field with
fossil fuels sooner is a price on carbon. "Everyone thinks an increase in
the cost of carbon is coming," said David Crane, CEO of NRG Energy Inc.,
in a recent article in EnergyBiz magazine. That would make the cost of
electricity from coal jump significantly.

The other primary challenge for CSP is the ability to produce energy
"24-7," the way fossil fuel plants can. Plants would need 16 hours of
storage to generate electricity around the clock. Ausra says it can store
energy at its prototype plants for 20 hours - a breakthrough that, if it
proves workable outside the pilot-plant stage, will place the company at
the head of the pack. Ausra's solar collectors employ a propriety storage
system, but the basic idea is to focus light onto tubes filled with water,
thus directly producing steam. Storing heat is more efficient than storing
electricity: just 2-7% of the energy is lost in heat storage systems,
compared with losses of at least 15% when energy is stored in a battery,
according to the MIT Technology Review. Ausra will start construction on a
175 MW commercial plant in California later this year.

We Shall Overcome

Transmission issues can be more complex than with fossil fuel plants, as
large CSP plants cannot always be built close to where power is needed. An
article in Scientific American recently laid out a "grand plan" to
massively increase solar power (both CSP and PV) in the US. It called for
replacing the existing system of alternating-current (AC) power lines
which lose too much energy over long hauls with a high-voltage,
direct-current (HVDC) power transmission system, which lose far less
energy than AC lines over equivalent spans. "The AC system is simply out
of capacity, leading to noted shortages in California and other regions;
DC lines are cheaper to build and require less land area than equivalent
AC lines," the magazine notes.

Water use is another potential drawback. Some CSP designs require water to
cool the plant, which is impractical in the desert. Experts say R&D is
needed to find air-cooling innovations. Some types, such as dish units, do
not require water for cooling. Plants can also be built near the sea,
where they could power desalination plants to produce their own cooling

A related environmental issue is the siting of large industrial solar
fields in fragile deserts. Clearly, care must be taken to minimize
impacts, to prevent CSP from being viewed as an unwelcome visitor in the
way that large wind farms have become in some settings.

Another siting issue relates to the relatively large tracts of land needed
for these projects compared to fossil fuel plants. Not all CSP plants are
equally land-guzzling. "We are more than two times more efficient when it
comes to land," said Rob Morgan, Ausra's chief development officer. Morgan
states that using Ausra's technology, it would take a square of land 92
miles on a side to "provide all US electric power - the entire US grid -
day and night" (US consumption is currently about 25% of electricity use
worldwide). "This amount of land is less than 1% of America's deserts,
less land than currently in use in the US for coal mines, and a tiny
fraction of the land currently in agricultural use," according to the
Ausra website. The company notes that CSP also has a much smaller land
footprint than large hydro.

These aren't insurmountable issues, but they will have to be addressed for
a mass rollout to succeed. Industry experts say that incentives are still
important for the near term to help the industry address these challenges.
The European Union has spent some €25 million in the past decade to help
develop this technology. In the US, an investment tax credit (ITC)
provides R&D incentive, but has to be renewed every two years, creating
uncertainty for those trying to develop projects.

Another type of incentive is feed-in tariffs, as is being tried in Spain.
These more direct forms of subsidy are not as good at encouraging
innovations that lead to price reductions, say some experts. "At those
prices, it's all project driven, you just want to get projects built,"
says Arnold Leitner, president of Skyfuel.

Under African Skies

What will it take (besides sunshine) for this technology to reach poorer
and middle-income countries? The potential is certainly there for the
nations with hot, dry climates. Two of the fastest-growing energy users,
China and India, are well endowed with desert solar resources to power
their economies. Mexico also has huge solar reserves close to major cities
in both Mexico and the US. And of course, the granddaddy of all deserts,
the Sahara, has many CSP experts feverish in anticipation.

Last year European engineers unveiled a plan to build thousands of
megawatts of CSP plants to connect via high voltage undersea cables to
northern Europe - enough to meet up to a sixth of Europe's electricity
needs. Engineers with the German Aerospace Center who carried out the
feasibility studies see the project "as a win-win scenario creating
energy, water and income for the Middle East and North Africa," according
to the BBC.

An article in the UK Guardian states: "The Desertec project envisages a
ring of a thousand of these stations being built along the coast of
northern Africa and round into the Mediterranean coast of the Middle East.
In this way up to 100 billion watts of power could be generated: two
thirds of it would be kept for local needs, the rest - around 30 billion
watts - would be exported to Europe." The plants' superheated steam would
be used to desalinate water (normally an energy-intensive operation).

The deserts of Africa would be a natural for CSP for domestic purposes
too, but thus far there has been little progress. In Southern Africa, the
South African utility Eskom has been studying plans for a 100 MW CSP plant
for many years, but the decision to build keeps getting put off. The site
chosen for the plant is one of the best in the world for solar. The
company hopes to use local producers for materials as much as possible.

A recent major power shortfall has Eskom in crisis mode, however, and it's
not clear if the new CSP plant will benefit from or be sunk by the
turbulence. What is clear, however, is that Eskom will need to find
cleaner ways to produce energy. Currently, coal-fired plants produce about
90% of South Africa's power. According to Eskom's CEO, if Eskom were a
country, it would rank 25th among the world's largest emitters of carbon
dioxide. The huge utility, which supplies power to neighbors as well, is
also looking to build a string of nuclear plants, and the world's biggest
dam on the Congo River.

Other Southern Africa nations are farther behind. Morteza Abekenari, the
CEO of Solar Power, a Botswana-based company that manufactures solar
panels, says he has for years been trying to convince local energy
authorities to buy into the idea of concentrating solar power, without any
luck. "When we started, we said that the sun was Botswana's diamond that
would last forever, but the idea of solar energy was like science fiction
here," he told the Francistown Voice.

Go Micro

It's not surprising that a small nation with low energy needs like
Botswana might balk at the big outlays of cash required for large-scale
CSP plants and the grid extensions they might require. But there is
another option that could prove workable for areas where grid expansion is
impractical. Micro CSP is a smaller scale version of its big brother that
is easier to install and can be cost-effectively shipped long distances.

At least one company, the Hawaii-based Sopogy, has developed a rooftop
unit that can power a single building or industrial complex. Unlike
standard CSP components, the Sopogy unit was developed with more humid
climates in mind, and the company is now beginning to market worldwide for
large industrial users and residential/hotel complexes. Their systems
range from 500KW-10MW.

"I believe there is great potential for micro-CSP to make a difference in
developing countries," says Sopogy's Al Yuen. "This is especially true for
the application of process heat for industrial purposes, which can be
generated at 60-70% efficiency and would be the lowest cost solar

Clearly, CSP is a very exciting alternative with huge potential - but like
other new renewables, it is only part of the solution. "No one thing will
be the answer to renewable energy to power the grid. CSP will contribute
more and more. Wind's role will grow. And ocean power has tremendous
potential. A little further out it might be organic solar cells and solar
cells that use nanomaterials. You'll see a combination based on geography
and cost," says NREL's George Douglas.

More information:

Concentrating Solar Thermal Power Now! is a "blueprint for action" that
aims to accelerate market introduction of CSP. The 2005 report (now being
updated for a late-2008 re-release), written by Greenpeace and the
European Solar Thermal Industry Association, "demonstrates that there are
no technical, economic or resource barriers to supplying 5% of the world's
electricity needs from solar thermal power by 2040 – even against the
challenging backdrop of a projected doubling in global electricity
demand." Download the report.


Promoting Green Building Design, Construction and Operation, Sustainable Living,
Clean Technology, Renewable Energy Resources and Energy Independence