The future of WTE - The new waste-to-energy developments that will change the industry
Waste to energy is growing in popularity, so what technologies are
emerging as a response to this? Felicia Jackson looks ahead and
discusses new developments
The WTE market is currently growing rapidly around the world. While
it has traditionally been a mature and slow-growing market, a perfect
storm of fears about pollution, the impact of climate change and the
growing focus on finding non-fossil fuel sources of energy, has meant a
renewed focus on the opportunities available.
There have been concerns raised about WTE. Namely that using waste
for fuel can encourage wastefulness and discourage recycling, and that
there are harmful by-products of the transformation of waste to energy,
including toxins and greenhouse gases. Yet new, cleaner technologies
developed over the last few years can often avoid the generation of such
by-products providing an effectively carbon neutral process.
There are a number of issues for developers in selecting a new
technology: the efficiency of the process itself, the reliability and
lifetime of the waste feedstock, local environmental impact in terms of
by-products, as well as planning and consumer and media opinion. Some
technologies provide only part of the process. For example, mechanical
biological treatment (MBT) or autoclaving treats and sorts residual
waste, resulting in streams of recyclable materials, organic materials
(often suitable for composting), other materials suitable for use as
refuse-derived fuel (RDF) and other inert materials. However, as part
solutions to the waste issue, they do leave some fractions of waste for
landfill and the resultant RDF is frequently used in straightforward
incineration.
Today’s technology
A number of new market technologies, such as anaerobic digestion,
pyrolysis and gasification, are in the process of being deployed. These
technologies provide the potential to recover products from the waste
stream which complete incineration would not allow – and a significant
proportion are focusing on biomass waste. Pyrolysis involves heating
waste in the absence of oxygen at very high temperatures, which breaks
down complex molecules and resultant gases are then passed into a
combustion chamber where they are heated (in the presence of oxygen) at
temperatures around 1250°C. The process produces liquid oil which is
used as a fuel, as well as gases that can be used to run steam turbines,
and chars. Gasification can be used with a far broader range of
feedstock, and simply involves heating wastes in a low-oxygen atmosphere
to produce a synthetic gas, which can then be used to power a steam
turbine.
With the advent of wider usage of technologies, the crucial questions
are scalability and the cost-effectiveness of each technology. One of
the reasons for the success of incineration is the lack of IP required
to develop a plant – this makes it simpler and relatively cheaper than
some of the more technically advanced forms of WTE for waste management
companies and local government to implement. Yet improvements in the
technologies, especially increasing efficiencies with new catalysts and
enzymes around improving bioreaction and pyrolysis technologies are
beginning to make an impact on the cost.
Another crucial requirement for the successful development of
waste-to-energy plants is to secure a sufficiently robust waste stream
and, to a great extent, different forms of technology will be
appropriate to one of a number of different waste sources.
Operationally, incinerators are reasonably immune to variable input
characteristics (they’ll burn most things) but they are vulnerable to
feedstock changes. They may lose energy content if, for example, plastic
packaging disappeared over the long term.
Landfill gas to energy has proved popular, especially given that the
dominant gas emitted from landfill, methane, has a global warming
potential 23 times that of carbon dioxide. However, the growing concern
about the pollutant impact of landfill means that there will be far less
landfill available in the future, which is likely to have a dramatic
impact on its role as an energy generator. This is an additional problem
with incineration, since ash residues from the process can be as high
as 25% by volume, most of it can go nowhere but to landfill. Chars
resulting from the pyrolysis process, for example when using rubber
waste such as tyres, may also generate toxins and require landfilling.
The necessary footprint of MSW incineration sites can also cause
problems. The majority of waste management and incineration sites have a
large footprint, with waste being trucked in from the surrounding
region. Such plants can have high operating and capital costs, requiring
long payback times, which can expose them to a higher risk of waste
stream content changes. The large scale of such plants can make the
power generated easier to integrate into existing grid networks but low
efficiencies mean that large quantities of waste may need to be trucked
in from the surrounding regions. And that need for large waste streams
causes concern regarding the impact on local waste reduction or
recycling streams.
Economies of scale
It is the large-scale nature of such waste management programmes that
is beginning to be questioned. There is a growing demand for locally
generated power, and an even stronger demand for local waste solutions.
Not only is there an accepted need to reduce the amount of waste that
our economies generate, but the logistical requirements for large scale
waste transportation have a significant carbon impact – another
increasing concern to industry and government. If the energy from waste
market is going to grow, it’s important to be able to deliver plants
with a small footprint, that can generate efficient power and heat for a
local district or industrial area, and that have an ongoing and
reliable fuel source. This will not only contribute to renewable energy
targets, but also counter many arguments which result in planning
opposition.
One of the key things that needs to be resolved is how to finance
such new infrastructure. Few of the existing large waste management
players have the capacity, the finance or the technologies to meet all
the new waste targets on their own, let alone those likely to be
enforced in the next few years. New technologies and new ways of
financing necessary facilities do exist however, with new businesses and
project financiers eager to follow the success of the wind market with
the waste and waste to energy market.
Traditional large scale incineration has been relatively easy to
fund, as the capital costs are clear, the technology well known, and the
revenue stream (through gate fees from local or regional governments)
easy to ascertain. This makes them appealing to traditional public,
project and debt finance. With many of the new technologies, investors
can be concerned about long term revenues, as there are few plants that
have been up and running for a long time, and many governments prefer
centralized solutions operated by businesses with large resources. This
puts pressure on small scale developers – they can’t bid for large scale
waste management contracts on the same terms as the established
industry players. This in turn can deter equity investors, and make it
problematic to raise either debt or equity funding.
Yet they can also have significant advantages over large scale waste
management solutions, financially and environmentally. Smaller plants
generate fewer waste miles and certain new technologies do not face
issues with the leachate and toxic fly ash so frequently associated with
incineration. They’re also cheaper to build and can be scaled up as
needed. As they are usually privately financed, local government need
not take on any capital expenditure – the plants are financed on the
basis of agreed revenue-bearing contracts such as gate fees for MSW.
One solution: Gasplasma
An effective WTE plant should be able to generate a number of revenue
streams: gate fees for the waste it receives, generated electricity
which is sold to the local grid on long-term power purchase agreements,
and potential revenue from the sale of recyclables removed or the sale
of heat to co-located industries. This approach is of growing interest
to the major European energy providers, who must boost their renewable
electricity output 15%-20% to meet the targets. With commercial waste
predicted to increase by 50% by 2020, the ability to build small plants
in industrial areas could transform the energy landscape with local
waste being used to produce local electricity.
One example of this is Advanced Plasma Power’s Gasplasma process,
which combines two well-established technologies, fluid bed gasification
and plasma arc conversion. APP’s original parent company Tetronics uses
plasma successfully in 33 sites around the world, in vitrifying
incinerator bottom ash and hazardous waste, as well as in metals
recovery. Gasification has been well proven in a number of markets from
coal to biomass. Aside from the initial power supply from the local
electrical grid, the whole process is self-sustaining after the initial
electrical charge is used. It is environmentally friendly, and it
produces materials that have commercial applications and thus can
generate further profit.
An average 100,000 tonne APP plant could generate six steady revenue
streams from each site: gate fees for the waste it receives; the sale of
all recyclables removed; the electricity generated (which is sold to
the local grid on long-term power purchase agreement); the heat sold to
industries that co-locate on the same site; double ROCS under the UK
Renewable Obligation scheme; and the sale of the glassy material,
Plasmarok, which is produced by the process and can provide a return as
it is sold as building material or aggregate. A plant would generate
11.5 MW of electricity, using 4.5 MW to run the plant, with the
remaining 7 MW exported to the local grid. This is enough for over
12,000 homes. With heat recovery, the process is over 65% efficient.
Even better, for those authorities’ conscious of the need to cut
their carbon footprints – its carbon contribution to the environment is
virtually nil. Analysis of the APP process has been shown to have a
‘negative’ carbon footprint in comparison to other forms of energy
generation, produce virtually zero emissions and has the highest
landfill diversion rate of any available technology, making it very
attractive to local authorities.
While plasma technology has been in use for many years it has only
recently been developed as a waste management solution. This was partly
because the conventional landfill approach was considerably less
expensive, even with transportation costs and gate fees, and there was
no regulated requirement for low-carbon energy. However, with increasing
landfill diversion targets and renewable energy targets, the relative
cost of the technology has been transformed. This is making plasma
gasification one of the most potentially exciting opportunities in the
sector.
The waste-energy partnership
There is no question that the energy mix of the global economy is in
flux, and we are going to see an increasingly broad range of solutions,
ranging from fuel cells to the implementation of a hydrogen economy. A
great deal of work is currently being undertaken at the cutting edge of
technology in developing flexible or multi-purpose fuels, and billions
of dollars are being invested to bring these opportunities to market.
Until those technologies become widely available, we must accelerate
our implementation of those technologies which work today. Energy and
waste policy are not correlated anywhere in the world, but there is a
significant amount of energy stored in waste and that is increasingly
being recognized in a resource-constrained world. Perhaps we need to
accept that the waste and energy industries cannot, and should not, be
mana
The
state government in Kochi, India has chosen the 'Swiss Challenge
System' of tendering, for its proposed 500 tonne per day Rs. 3.5 billion
($65 million) waste to energy plant in Brahmapuram.
Hyderabad, India based waste management and environmental services company, 
