Middle Tennessee State University Sustainable Wind Power Paper Formatting (Spacing, font, etc.) 10 points Grammar (Spelling, grammar errors) 10 points Cont

Middle Tennessee State University Sustainable Wind Power Paper Formatting (Spacing, font, etc.) 10 points Grammar (Spelling, grammar errors) 10 points Content (Explain the Article in 100 words) 10 points APA Reference formatting 10 points Richmond Carvey
IME 1020
September 28, 2005
Hydrogen: The New Fuel?
(Abstract)
Hydrogen as a replacement for gasoline faces many obstacles. Hydrogen production uses
a process called electrolysis, but production is very expensive. The cost is not the only
speed bump encountered by researchers; they have also found that hydrogen leaks out of
the smallest of cracks and can break down steel and other metals. These characteristics
of hydrogen are hard to get around; however, the benefits of hydrogen outweigh the
hazards of stand-alone gasoline products. Hydrogen is a good replacement for gasoline,
but with the current success of gas/electric cars, the conversion to a hydrogen economy
will most likely be postponed.
Dvorak, P. (2004). Heading toward the hydrogen economy. Machine Design, 76(18),
92, 94, 96, 98. Retrieved September 26, 2005, from the ASTA Database.
Feature article
Recycling wind
turbine blades
WITH A BOOMING WIND ENERGY INDUSTRY, DRIVING THE DEVELOPMENT
OF LARGER AND LARGER TURBINES, THE QUESTION IS NOW ARISING OF
HOW TO DEAL WITH WIND TURBINES AT THE END OF THEIR LIFECYCLE, AND
PARTICULARLY THOSE WIND TURBINE BLADES MADE OF HARD-TO-RECYCLE
COMPOSITES. RENEWABLE ENERGY FOCUS’ KARI LARSEN INVESTIGATES
POSSIBLE ROUTES FOR THE RECYCLING OF WIND TURBINE BLADES.
The global wind industry is growing fast, in
terms of both the number of turbines and
their sizes. According to the Global Wind
Energy Council (GWEC), modern turbines are
100 times the size of those in 1980. Over the
same period, rotor diameters have increased
eight-fold, with turbine blades surpassing 60 m
in length.
young, there is only a limited amount of practical experience on the recycling of turbines
– particularly offshore, and it will take time to
gain practical experience in the dismantling,
separation, recycling, and disposal of windpower systems.
Wind turbine blades typically consist of reinforcement fibres, such as glass fibres or carbon
fibres; a plastic polymer, such as polyester or
epoxy; sandwich core materials such as polyvinyl chloride (PVC), PET or balsa wood; and
bonded joints, coating (polyurethane), and
lightning conductors.
At the moment, there are three possible routes
for dismantled wind turbine blades: landfill,
incineration or recycling. The first option is
largely on its way out, with countries seeking
to reduce landfill mass. Germany, for example,
What are the current options?
introduced a landfill disposal ban on glass fibre
reinforced plastics (GRP) in June 2005, due to
their high (30%) organics content such as resin
and wood.
The most common route is incineration. In
so-called combined heat and power (CHP)
plants, the heat from incineration is used to
create electricity, as well as feed a district
heating system. However, 60% of the scrap is
left behind as ash after incineration. Due to
the presence of inorganic loads in composites,
this ash may be a pollutant, and is, depending
on the type and post-treatment options, either
250,000
As turbines grow in size, so does the amount
of material needed for the blades. Professor
Henning Albers from the Institut für Umwelt
und Biotechnik, Hochschule Bremen, estimates
that for each 1 kW installed, 10 kg of rotor blade
material is needed. For a 7.5 MW turbine, that
would translate into 75 tonnes of blade material. In a presentation at Composites Europe in
September 2008, Albers predicted that by 2034,
around 225,000 tonnes of rotor blade material
will need to be recycled annually worldwide.
World without Europe
Europe without Germany
Germany
Blade material, Mg/a
Wind turbine blades are predicted to have a
lifecycle of around 20-25 years. The question is
what to do with them afterwards.
200,000
150,000
100,000
50,000
0
2020 2021 2022 2023 2024 2025 2026 2027 2028 2029 2030 2031 2032 2033 2034
Ref.: WindEnergy-Study 2006, fk-wind-data base
The problems is – according to experts –
because the wind-turbine industry is relatively
70
renewable energy focus
Figure 1: Expected amount of rotor blade material world wide
January/February 2009
Year
Wind/Blade recycling
dumped at a landfill or recycled as a substitute
construction material. The inorganic loads also
lead to the emission of hazardous flue gasses
in that the small glass fibre spares may cause
problems to the flue gas cleaning steps, mainly
at the dust filter devices.
Wind turbine blades also have to be dismantled
and crushed before transportation to incineration plants, placing further strain on the environment in terms of energy used – and emissions.
Albers suggests that there are also causes for
concern in relation to the health and safety of
workers involved in the incineration process.
The alternative is recycling – either material
recycling, or product recycling in the form of
re-powering – where old turbines are replaced
by newer, more efficient ones. At the moment,
however, there are few established methods
for the recycling of wind turbine blades, and
only 30% of fibre reinforced plastic (FRP) waste
can be re-used to form new FRP, with most
going to the cement industry as filler material.
So what attempts have been made at recycling
projects to date?
Recycling projects
REACT
Between 2003 and 2005, a project led by the
consultancy company KEMA and the Polish
Industrial Chemistry Research Institute
(ICRI) looked at the mechanical recycling of
FRP, including wind turbine blades, where
the material is ground and then re-used.
Funded by the European Commission’s CRAFT
project, the REACT project also involved HEBO
Engineering, C-it, Fiberforce Composites
Ltd, Hamos GmbH, Plasticon, ZPT and the
European Composite Recycling Services
Company (ECRC).
The REACT consortium, through HEBO and
KEMA, designed, built and tested a hybrid
shredder for ‘fit-for-purpose-size’ reduction.
The shredder has a capacity of 2.5 tonnes/
hour and can reduce FRP to 15-25 mm with
“minimal internal damage” to the fibres. This
was done with hammers slamming the resin
out of the fibre structure. To avoid dangerous
situations during grinding, an electronic sensor
for volatile organic compounds (VOC) was
developed by C-it.
After shredding, the fibre was upgraded by a
reactivation method, specially developed by
A wind turbine blade before and after pyrolysis. (Picture courtesy of ReFiber.)
ICRI to achieve better properties through a
new chemical bonding with the new matrix.
Another technology was developed by HAMOS
for fibre length separation, and the removal of
undesired impurities.
One of the problems in reusing shredded FRP
waste is to rebind fibres with the new resin, as
the shredded fibres often have resin residues,
making bonding more difficult. Bart in’t Groen,
consultant at KEMA, remarks: “you need longer
fibres to have good bonding with your new
matrix compared with virgin fibres.”
For wind turbine blades, an additional step is
required. The blades must be cut into chunks
on location to ease transport. This can be done
with a demolition claw (a crushing/grabbing
claw attached to the end of a crane or digger),
a technology which is widely available.
Initially, the REACT project aimed high when
it came to possible applications for FRP
recyclate, but found that there was not the
same demand for composite recyclate as for
materials such as steel. The consortium therefore started looking at smaller, more niche
markets. Examples include parts for FRP silo
tanks, reinforcement of concrete, new hand
laminate products, reinforcement of recycled
polyproplene (PP) resin, sand-resin mixture
for producing large flower pots, and sandwich
panels.
One challenge that arose when turning to the
composite industry itself was product guarantee certificates, as found in the boat building
industry. When using recyclate, companies
often feel they are taking a risk with the materials, thereby endangering their guarantee
certificates.
Another challenge is that recycled fibres
will be shorter than original fibres, coated
with some ‘historical’ resin, and are harder
to arrange in a given direction. This makes
it more difficult to increase strength, as is
needed, for example, in car bumpers. This
has not stopped the car industry from recycling and reusing its own waste, however.
According to in’t Groen, it is just a matter of
knowing your input material.
Despite the challenges, he is keen to point out
that the recycling of FRP materials, including
wind turbine blades, is important: “Because
composite usage and so its end-of-life waste
will increase enormously…, so a lot of initiatives are there and solutions will be found. It’s
a waste dumping this material.”
renewable energy focus
January/February 2009
71
Wind/Blade recycling
ReFiber’s recycling concept in short
■ On site cutting to ‘container’ size pieces
■ In a second rotating oven the glass fibre
with hydraulic shear or similar tools;
■ Once at the plant, the parts are shredded
to hand-sized chunks;
■ The material is fed continuously into
an oxygen-free rotating oven with a
temperature of 500° C – the plastic is now
pyrolysed to a synthetic gas;
■ The gas is used for electricity production as
well as for heating the rotation ovens;
material is ‘cleaned’ in the presence of
atmospheric air;
■ Metals are removed by magnets for recycling;
■ The dust is removed from the clean glass
material remaining;
■ The glass fibres are mixed with a small
amount of polypropylene fibres and pass
through an oven where the PP fibres melt
and connect to the glass fibres creating
stable insulation slab.
However, Dr Richard Court, Technology
Specialist – Wind Renewables at the New and
Renewable Energy Centre (NaREC), points
out that “grinding uses a lot of energy due to
the hardness of the glass, and the value of the
filler is quite low, so it is not easy to make it
economic – unless you find a cheap source
of energy.”
The end products from ReFiber’s pyrolysis are
primarily thermo-resistant insulation materials.
The fibres can also be used for fibre-reinforcement in filler, glue and paintings, thermoplastic
parts, asphalt and concrete; and raw material
for new glass fibres. The energy content of the
composites is used for generating electricity,
for process energy and district heating.
ReFiber
Erik Grove-Nielsen, of ReFiber ApS in Denmark,
remarked in a presentation at Borås University in Sweden in 2007 that mechanical recycling in the form of material crushing retains
the tensile strength of glass fibre, but that it
gives impure end-materials. The filler market
is flooded with similar materials such as chalk,
and the energy content is not recovered.
A recycling possibility is chemical recovery
through solvolysis. With this method, most
of the tensile strength of the glass fibre is
retained, and the plastic material can partly
be used as new raw material. However, GroveNielsen questions the use of aggressive and
hazardous chemicals, and highlights the
high cost.
The option favoured by ReFiber is thermal and
material recovery in the form of pyrolysis and
gasification. Although the fibres lose a “considerable part” of their original tensile strength,
and despite the high cost of the technical plant,
the end product is very “homogenous,” and the
energy content of the plastic is recovered (see
box – ReFiber’s recycling concept in short).
72
renewable energy focus
It makes sense to develop
a recycling industry to
maturity before the big
amounts arrive.
“As of today, most Danish worn-out blades and
production failures are sent to landfill, as this is
the cheapest solution for the companies,” says
Grove-Nielsen. “ReFiber tried to get finance for
a 5000 tonnes/year recycling facility, [but] as it
is possible to dump the material on landfills,
[that] is what is done. The possible investors
didn’t feel safe… so we had to set the project
on stand-by for some time.”
The 5000 tonnes/year facility would be fed by
approximately 4000 tonnes of production waste
from the Danish GRP industry, 500 tonnes/year
from worn-out wind turbine blades, and 500
tonnes/year of other glass fibre waste. GroveNielsen predicts that there may be a supply of
blades from the wind turbine retrofit market
in Northern Germany in the near future, as
older, smaller turbines are decommissioned
and replaced by new, bigger and more efficient
versions. There is also the possibility that some
of the better turbines may be sold to Eastern
European countries for a ‘second life.’
“For the early years we will have to depend
on delivery of production waste and worn out
GRP products other than blades. The real big
amounts of worn out blades will emerge 15
years from now. It makes sense to develop a
recycling industry to maturity before the big
amounts arrive,” Grove-Nielsen says.
In 1995, the Danish Government passed legislation banning the disposal of rubber car tyres on
landfill and through incineration, which created
a new recycling industry for car tyre rubber, but
no such approach has been taken for GRP.
“We asked the Government here to do the same
for GRP recycling, but they want ‘the market’ to
solve the problem,” Grove-Nielsen says.
Grove-Nielsen does not believe that the recycled GRP wind turbine blade material can be
reused in new blades, however: “Recycled glass
fibres will always have lower strength than virgin
materials. Therefore the industry cannot use
recycled reinforcement fibres. For carbon fibres
it is different. ReFiber has recovered, in its pyrolysis facility, carbon fibres from prepreg epoxy/
carbon material with unchanged E-modulus
and only 5% lower values for ultimate tensile
strength. Still, for the glass fibre, it makes sense
to allow the glass fibres to ‘retire’ for a life as a
heat insulation material in buildings.”
Viability of recycling
Despite ReFiber’s apparent success in establishing a disposal and recycling route for
GRP and wind turbine blades, finances have
stopped the project:
A similar point was made by Thomas Wegman,
Director Global Account Management at
Reichhold Composites and Chair of the European Composite Recycling Company (ECRC).
January/February 2009
Per Dannemand Andersen, Head of Section,
Department of Management Engineering, Technical University of Denmark, suggests that the
problem is not the material itself, but the lack
of volume, making recycling financially difficult:
“There are now technologies available to reuse
fibre-glass and blades from wind turbines and
other components in cars. The problem is not
technologies, but… that there is not enough
scrap […] so it is not commercially viable to
put up a plant that could use only these blades.”
Wind/Blade recycling
The ECRC has an active conversion system in
place in France, where composite materials are
reduced to smaller parts, fibres and powders,
and then sold on to different applications. To
their surprise, the amount of material offered
for recycling and processing does not amount
to what the outlets are capable of receiving.
“I think the reality is that the quantity of
waste that is offered to us, as well as other
companies, is relatively small. If you’re talking
about waste streams that can be used in
cement manufacturing, people are looking at
hundreds of tonnes per week – well, I think
we’re currently receiving tens of tonnes per
year,” Wegman says.
Court at NaREC, however, believes the material
is part of the problem: “Industries that use a lot
of thermoset composite materials tend to make
longer-lived items, and are probably waiting to
see what, if any, recycling options are developed
in the coming years. I am sure the wind turbine
blade industry would welcome any research
into recycling of thermoset composites –
although from my own awareness of the materials and chemistry of thermosets, it’s difficult to
see what those recycling options could possibly
be. Recycling thermoset composites is certainly
a major challenge, and it will be interesting to
see what developments are forthcoming.”
Wegman at Reichhold and ECRC is more optimistic looking 15-20 years ahead in time: “I
would say that recycling is going to become
more important.… For environmental reasons,
but also for economic reasons.”
Recycling is going to
become more important. . . .
For environmental reasons,
but also for economic
reasons
Who’s responsibility is it?
Who is responsible for what happens to wind
turbine blades at the end of their life cycles?
Albers says that typically the responsibility
ends up with the manufacturer of the end
product, as seen in the car industry.
As far as renewable energy focus has been able to
establish, there is no European-wide legislation
in place for the recycling of wind turbine blades.
Wegman believes this could come at some
point in the future, whilst remarking that “there
is a desire from the manufacturing companies
and the people involved in composite businesses to find ways to actively [find solutions]
and not wait for legislation to come.”
Working with the ECRC, Wegman finds that
the waste streams are not unmanageable at
the moment, but a solution must be found.
“We will work step by step towards a sustainable structure based on commercial outlets for
composite waste. ECRC has access to unlimited
industry expertise to make this happen.”
New materials
Some thought has gone into developing new
ways of producing wind turbine blades to make
the disposal and recycling process easier. Court
at NaREC explains: “There are… thoughts about
trying to use thermoplastic matrix composites
in wind turbine blades, the idea being that thermoplastics are easier to recycle, as evidenced in
the automotive sector. Whether the mechanical
and physical performance of the thermoplastic
based materials is sufficient for a multi-megawatt wind turbine blade has yet to be proven.
For micro-wind turbines, e.g. up to around 5 kW,
it is possible to, and some do, use some form
of moulded thermoplastic, reinforced or otherwise – in which case recycling is much more of
a possibility.”
In September 2008, Risoe DTU announced it
is aiding the Chinese forestry commission to
examine the use of bamboo in wind turbine
blades. The blades will initially be made from
bamboo shreds glued together using epoxy, but
the hope is to be able to replace the synthetic
epoxy material with a bio-based adhesive.
Reichhold and ECRC’s Wegman believes it is
not just about making the resins more recyclable or greener: “When you make a complex
product like windmill blades, it’s not just one
material, it’s… a system. Sometimes there
are metal parts inside for specific functional
reasons and there are different core materials
which can range from PVC to balsa wood – so
it’s a complex system.
“For Reichhold as a company to just develop a
specific resin that would be more easily recycled – I don’t think that’s what we’ve looked
at, as this is only one element of a composite
system – we’ve taken the route of working
together with some other companies making
reinforcements, fillers and other components
to take an integrated approach and to get
Composite recycling
companies
ERCOM Composite Recycling (19922004) – terminated due to economic
problems. Used crushing and separation
in different particle sizes and material
recovery. Put recycled products into new
products (10%-40%);
Seawolf Design Inc of Florida, USA – uses
non-destructive reduction of fibres with
special mill technique. Possible fixation of
glass fibres with spray-up systems as filling
material in new products;
ReFiber ApS of Denmark – pre-crushing
to 25 cm × 25 cm, then pyrolysis at 500° C,
separating into glass fibres, metal and filling
material, but sees 50% loss of fibre strength.
Applications include insulation materials.
rid of the waste and reusing the waste in a
good way.”
Philipp Angst, Product Manager Core Materials at Alcan Airex, part of Alcan Composites
Core Materials, advocates the use of polyethylene…
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