Assessment of the potential impacts of solar farms on individual birds and
their populations is a topic that I've recently become involved in as part
of my consultancy work. The Daily Mail article brought to our attention by
Mike completely misrepresents the known impacts of solar power generation on
birds, at both the individual solar plant level and the solar power industry
level overall.
First, it is important to be aware that there are two main types of
large-scale solar farms - those that generate electricity through the use
of:
1. Photovoltaic cells [conversion of solar energy into direct current
electricity using semiconducting materials that have photovoltaic
properties];
and
2. Solar thermal technology [the use of heliostat mirrors to collect and
reflect light and heat to receiving boxes or tubes containing pipes that
carry a fluid (usually molten salt or salty water) that heats up and
produces steam that can be used to drive turbines]. There are three main
types of solar thermal energy collectors:
(a) solar power towers: vertical towers which contain one or more receiving
boxes on or near the top of the tower that collect(s) the reflected light
and heat from the heliostat mirrors surrounding the towers.
(b) parabolic troughs: a row of curved mirrors, arranged to form a long
parabola, reflect light and heat onto a dewar (vacuum) tube that runs the
length of the parabola's focal line.
(c) Fresnel reflectors: long, thin segments of mirrors are arranged
linearly to focus sunlight onto a fixed absorber located at a common focal
point of the reflectors. These reflectors make use of the Fresnel lens
effect, which allows for a concentrating mirror with a large aperture and
short focal length while simultaneously reducing the volume of material
required for the reflector.
Preliminary research at solar power facilities show that bird mortalities do
occur at solar power plants, but the numbers of bird casualties are
relatively low compared with other anthropogenic causes. Most of what is
known about the impacts of solar farms on bird populations is based on a
study by Kagan et al. (2014) at three solar farms in the United States
(southern California) that use different solar designs (photovoltaic cells
at the Desert Sunlight Facility, a trough system with parabolic mirrors at
the Genesis Facility, and power towers as focal points for solar flux at the
Ivanpah Facility).
Kagan et al. (2014) recorded mortality or injury to 71 bird species across
the three solar farms, representing a broad range of ecological types. Each
solar farm is located in significant migratory paths of bird species, and
sampling was conducted in October 2013, during the southward autumn
migration period. Impacted bird species ranged in size from hummingbirds to
pelicans; in ecological type from strictly aerial feeders (swallows) to
aquatic feeders (grebes) to ground feeders (roadrunners) to raptors (hawks
and owls). The species identified were equally divided among resident and
non-resident species, and nocturnal as well as diurnal species were
represented. However, despite the relatively high number of species
impacted, the total number of impacted birds found across all three solar
farms was low (233 individuals). Additional surveys at the Ivanpah Solar
Facility conducted over a 17-month period (July 2012 to December 2013)
resulted in the recovery of 141 bird carcasses from the area, and included a
7-month period when the facility was under construction and the towers were
not fluxing.
This study identified the main risks to birds from solar power plants to be:
1. loss of bird habitat;
2. collision risks with solar farm infrastructure (heliostats, towers and
cables);
3. solar flux burns and related trauma;
4. heliostats and reflected light perceived by birds as wetlands;
5. attraction of birds to bright lights at night;
6. attraction to insect culls and live swarms; and
7. stranding and predation.
The relative importance of each of these risks varies considerably according
to the type of solar power generation employed. For instance, impact trauma
from collisions with structures and increased predation (by raptors) were
the main causes of mortality at the Desert Sunlight and Genesis Facilities,
with some waterbirds at the Desert Sunlight also unable to take flight again
after landing on a large flat areas provided by the photovoltaic panels
(i.e. strandings). Solar flux burns and impact trauma were the main causes
of death at the Ivanpah Facility.
In comparison, estimated annual bird mortality rates in North America
(number of birds killed per year) from other anthropogenic sources include
1.4 - 3.7 billion from predation by cats, 98 - 980 million from collisions
with buildings and windows, tens of thousands to 174 million from collisions
and/or electrocution from power lines, 60 - 80 million from collisions with
road and rail vehicles, 6.8 million from collisions with communication
towers, 500,000 - 1 million at oil field waste water facilities, 209,059 -
330,010 from collisions with wind turbines, and 4,722 from collisions with
aircraft. Therefore, preliminary studies suggest that bird mortality and
injury at solar facilities are likely to be much lower than those caused by
other anthropogenic sources.
On 14 January 2015, about 115 bird mortalities were recorded during a
4.25-hr test run of the TSE Crescent Dunes Solar Energy Project (CDSEP), a
110 MW solar thermal facility that was the subject of the Daily Mail
article. The facility consists of 17,500 heliostat mirrors that collect and
focus the sun's thermal energy to heat molten salt flowing through a single
160-m tall receiving tower. It is one of the largest, if not the largest,
solar power facilities, in the world. The bird mortality recorded at the
CDSEP occurred when about 3,000 heliostats surrounding the receiving tower
were positioned to reflect light and heat to a concentrated point above the
tower (approximately 360 m above the ground) during the test run. The
technical report that I read of this incident stated that a halo of energy
was visible from the ground, and the heat was so intense that birds flying
into the halo were immediately burned and smoke was clearly evident. Normal
operation of CDSEP would require the heliostats to reflect the solar energy
to, rather than above, the receiving tower, reducing the risk of energy
concentration points occurring in flight paths of bird flocks. Subsequent
test runs at the CDSEP, where solar energy is focused at a point above the
tower, are limited to the use of 150 heliostats at any one time, but avian
mortality data under this regime are not yet available.
Overall, the benefits gained by installing a solar power facility are likely
to outweigh the risks posed to bird species, especially if bird hazard
management plans are implemented to reduce bird mortalities. For instance,
solar power plants counteract human-induced climate change, which is one of
the most significant global threats to birds today. 1 MW of solar energy
offsets between 680 to 1,700 tonnes of CO2 emissions per year that result
from the burning of fossil fuels. Most solar power plants today are between
30 & 110 MW facilities. Therefore, a 30 MW solar facility would potentially
offset between 20,400 and 51,000 tonnes of CO2 emitted per year. A 110 MW
solar facility would potentially offset between 74,800 to 187,000 tonnes of
CO2 emissions per year from the burning of fossil fuels. To put that in
perspective, an average vehicle emits about 5.1 tonnes of CO2 per year, thus
1 MW of solar power could offset between 133 and 333 vehicles per year.
Therefore existing solar power plants offset carbon dioxide emissions
equivalent to removing 3,990 to 9,990 cars from the road (for a 30 MW solar
power facility) and between 14,630 and 36,630 cars from the road (for a 110
MW solar power facility.
The Daily Mail article failed to recognise that bird impacts are low
compared to other anthropogenic causes of bird mortality, and also failed to
differentiate between the different types of solar power plants and their
differing impacts on birds. In the way it reported the CDSEP incident, it
gave the impression that the rate of bird mortality recorded would continue
at that level, when in fact it was an abnormal, albeit unfortunate, incident
that probably would not be repeated. But I think the biggest crime was for
the article not to consider the benefits that solar power generation
potentially has in offsetting impacts of global warming, particularly
climate-change impacts on bird populations from the burning of fossil fuels.
Large-scale solar farms are beginning to be established in Australia.
Studies of the impacts of these farms on Australian birds are just beginning
to get underway. Until we have some Australian data, we will have to rely on
the results of overseas studies.
Kind regards,
Stephen Ambrose
Dr Stephen Ambrose
Director
AMBROSE ECOLOGICAL SERVICES PTY LTD
m: 0402 225 481 t: 02 9808 1236 f: 02 9807 6865
PO Box 246, Ryde NSW 1680
web: www.ambecol.com.au
LinkedIn: http://au.linkedin.com/in/drstephenambrose
Reference:
Kagan, R.A., Viner, T.C., Trail, P.W. and Espinoza, E.O. (2014). Avian
mortality at solar energy facilities in southern California: a preliminary
analysis (National Fish and Forensics Laboratory, Ashland).
http://alternativeenergy.procon.org/sourcefiles/avian-mortality-solar-energy
-ivanpah-apr-2014.pdf.
-----Original Message-----
From: Birding-Aus On Behalf Of
John Leonard
Sent: Wednesday, 4 March 2015 12:14 PM
To:
Subject: Solar-power that kills birds
The daily mail isn't a reliable source of information about anything.
John Leonard
> On 4 Mar 2015, at 12:08 pm, Michael Tarburton
<> wrote:
>
> G'day Readers
>
> Cats, and wind turbines are not the only thinks killing birds. This
article is from the USA, but it might pay us to be aware of the problem.
>
> This is just one of the links to newspapers dealing with the issue, but it
is less encumbered with forced advertising than the one my wife sent me.
>
>
http://www.dailymail.co.uk/sciencetech/article-2965070/Solar-farm-sets-130-b
irds-FIRE-Extreme-glow-power-plant-ignites-creatures-mid-air-tests.html
>
> One article says Obama is ignoring the issues on this one, another says
Google is part owner & that might explain why some of my searches goofed up!
>
> Sad reading
>
>
> Mike
>
> ===================
> Michael Tarburton
>
> ===================
>
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