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A Sustainable Energy Web
Summary
Why not combine different types of energy generation, using sustainable methods, so that the weaknesses of one method or cancelled out by strengths of another? This approach is suggested in the following and is encapsulated in the concept of a "Sustainable Energy Web".
The system seeks to overcome some of the problems of using
complimetary, or "alternative" methods of power generation. Various
systems are combined to achieve a higher level of overall efficiency and
reliability. In addition, a "heat store" is used to smooth out the
bumps and dips of energy generation an allow a better match between supply and
demand.
Background
A great deal of research is presently going to develop methods of
generating electricity using sustainable methods. Much of the research is
targeted at producing viable products with greater efficiency at lost cost.
However, current proponents of such systems tend to specialise: wind
turbine specialists focus on wind power, wave power specialists focus
on wave power, and so on. There is some overlap between the specialists, but
not much. This may be partly due to a mixture of ideology, economic factors
(i.e. competing products), or lack of cross-disciplinary expertise.
Each method of generating energy has its strengths and weaknesses: wind
power is fairly cost-effective, but output is related to wind speed rather than
the cycles of demand; hydro power gives more consistent output than wind power,
but has limited availability. In addition, each method of generation has it's
own level of environmental impact depending on the resources required to
establish the generation and power distribution systems.
The various types of sustainable energy generation systems have now
evolved to the point where it is worth taking a fresh approach to the issue of
power generation. This approach would establish projects that bring different
methods of power generation together into a system that allows the strengths of
one system to offset the weaknesses of the others.
There are, of course, organisations (such as The Centre for Alternative
Technology in Wales) who have tried to bring different energy systems together.
However, the primary focus of such organisations is to demonstrate that the
technology works on a small scale. They are not geared to put together a medium
to large scale integrated energy system. Nor are they structured economically,
or organisationally, to operate the system in such a fashion as to generate not
only electricity, but also a financial surplus. Yet, sustainable methods of
energy generation must prove themselves economical if they are to become more
than just a fringe activity.
An Integrated Approach
The field of energy generation using "alternative" or
sustainable methods would benefit from the application of a more general
approach. One that looks to see how the different systems available can be used
together to the best overall effect.
This system would be designed to:-
·
Create greater overall efficiency.
·
Match the overall power generation pattern to the demand cycle.
·
Minimise environmental impact.
·
Be designed to suit local energy needs and power generation
opportunities.
Underlying the above would be a business-like approach and the
intention to generate a financial surplus.
Such a system would bring various sustainable energy generation methods
into a cohesive whole. To ensure reliability, the system would not be too
dependent on any particular part. In this respect it would operate like a
"web": A Sustainable Energy Web.
A Sustainable Energy Web
A Sustainable Energy Web is based on a whole system approach to energy
generation and consumption. A number of different types of energy generation
plants are combined into a more efficient and more sustainable system.
The basic principles behind a Sustainable Energy Web are:
·
Match the range of systems to local generation and consumption needs.
·
It can utilise all suitable forms of energy potential including
everything from sewage gases to solar power.
·
All forms of energy output are seen as part of the system, including
not only electricity and heat, but also food production.
·
The system is a "web": each component of the system is both
independent and interdependent. The system is designed to operate with the
different components interconnected to give the greatest overall efficiency,
but useful output is still achieved if any component goes off-line.
·
The generator mix is selected so as to minimise environmental impact.
The range of possible energy sources and type of energy usage makes it
suitable as a "community business" with a percentage of any surplus
going into grants to local people for insulation, low-energy light bulbs etc.
However, it is also possible that the operation could be run as a small
business.
Applications of a
Sustainable Energy Web
Before looking at a possible application for a Sustainable Energy Web
it is important to have a broad sense of what some of the technologies used
have to offer. While the basic principles of the likes of a wind turbine may be
obvious to many, other key technologies such as Fuel Cells and Stirling Engines
are not so well known and these are briefly explained below.
Fuel Cell
A fuel cell is somewhat like a battery in that it produces electricity
by the same method (i.e. electro-chemically). However, the difference between a
battery and a fuel cell is how the later is recharged. A fuel cell is
continuously recharged by a supply of combustible fuel in the form of a gas
such a hydrogen, or methane.
There is now a significant amount of research taking place in making
fuel cells more cost-effective. However, they are already commercially
available with some suppliers already providing models that generate in excess
of 100KWatts. These systems are still
relatively expensive per KWatt. However, there are ways to improve the benefits
from operating a fuel cell. The main by-product of a fuel cell is heat. The
heat can be used to supply a local heating system or used to generate
electricity by additional means thereby making the whole system more efficient.
Some of the research into fuel cells is targeted at ways of producing
the gas to supply a fuel cell from biological waste (such as manure, distillery
waist on so on). Such an approach has obvious attractions from the perspective
of sustainability.
Stirling Engine
The Stirling Engine runs on heat. Heat is applied to the engine and is
converted to mechanical energy, which in turn can power electrical generators.
The Stirling engine pre-dates the internal combustion engine. Unfortunately the
Stirling engine does not accelerate effectively. It is better suited to running
at a steady speed, so it lost out to the internal combustion engine. However,
efficient operation at a steady speed is what is required for electrical
generation and this is one of the factors behind the resurgence of interest in
the Stirling Engine.
Other factors behind current developments in Stirling Engine are that
they can run on "low-grade" heat. This means that actual temperature
of the heat applied to the engine does not need to be significant. Indeed it is
possible for a demo model Stirling Engine to run of the heat of a cup of tea
and some demo models are available that can even run from the heat from the
palm of a hand. However, impractical these models are they show the flexibility
of the Stirling Engine.
There is much commercially orientated research being undertaken in
regard to Stirling Engine and products are available particularly from Sweden
and the U.S.A.
An Example Sustainable
Energy Web
Below is an example of how the Sustainable Energy Web model can be
applied. It should be borne in mind that the system would be matched to suit
local needs and that the following is simply one example.
Example of a Sustainable Energy Web
Biological waste is used in a biomass system (1) to generate the gas used to supply the fuel cell (2) with the energy it needs to generate
electricity. The biological waste used would be depend on local availability
and could be concentrated sewage, animal waste, distillery waste, and the like.
What happens to the biological output from the biomass process depends on its
composition and local needs. However, the material would leave the process in a
more much manageable state than when it entered.
If a source of organic waste were not available others options
including commercial gas could be used. It is also possible to use electrolyses
to extract hydrogen from water and use that to supply a fuel cell.
The fuel cell (2) converts
the gas input to electricity, which is routed to the power distribution module
(3). A major by-product of a fuel
cell operation is heat. The heat is sent to the heat storage module (4).
The heat Storage (4) module
is like a flywheel for the system. It stores heat produced by the fuel cell as
well as from the Solar Collectors (6)
and any other heat sources available. The Heat Storage module supplies energy
to the Stirling Engine Powered Generators (5),
which produce electricity from the heat.
The Heat Storage module (4)
also supplies a small amount of heat to the Biomass process (1) to keep it at an efficient
temperature.
Excess heat from the Heat Storage can be offered via the Heat
Distribution module (7) to a District Heating system, a commercial or community
facility, Greenhouses for commercial food production, and the like.
Additional options
Various possible additions to the above were left out for simplicity.
Additional systems could easily be added to the above to augment it with wind,
wave, or hydro power. In addition, if the system were near a body of water a
heat pump could be used to extract heat for the heat store.
The advantages
An advantage that a Sustainable Energy Web offers wind power is the way
that excess energy could be stored in the heat store and later generated as electricity
at times of peak demand. Overall, by combining various forms of energy
generation with a central heat store a Sustainable Energy Web overcomes many of
the problems associatd with generating energy from complimentary sources.
It allows the supply to be better matched to the demand cycle.
It provide a high level of reliability as the overall system is not
overly dependant on any one source of generation.
It can provide solutions to problems that initially may not seem at all
related to energy generation. For example it can alleviate waiste disposal
problems. Indeed certain types of waist can be seen as commodity rather than a
problem.
Economic factors
Costs
Cost would, of course, be a factor in the choice of components for a
Sustainable Energy Web. There is a significant amount of development taking
place to produce increasingly cost-effective versions of sustainable energy
generation systems. The costs associated with many systems are reducing.
However, any pilot project is bound to be subject the additional costs
associated with early adoption.
It may be possible to participate in proving trials of some equipment
in order to get them at reduced cost and to gain access to needed expertise by
participation in research projects.
Income
The energy produced could be sold to a local community with excess
being sold back to the national grid. The best options for when to resell and
when to store the energy would need to be determined for each location.
Changes in regulations within the UK have increased demand for
"green" energy and it is likely to find a ready market. The major
energy companies are increasingly looking for sources of sustainable energy and
this will drive down prices and create new opportunities.
Funding
The funding for a Sustainable Energy Web would depend on its
application and the ownership structure. Owing to the costs of early adoption,
a pilot project would probably require grant assistance. It would also be advantageous
if some of the more expensive components of the system (such as fuel cells)
could be obtained through participation in action research projects. Companies
producing suitable products would likely be interested in such research as it
would show their products at their highest efficiency and therefore in the best
possible light.
Electricity companies may be interested in supporting the development
of Sustainable Energy Web. Not only is it a potential source of renewable
energy, but also, it can reduce the cost of provision. A Sustainable Energy Web
can reduce the demand for electricity from the grid in rural and remote areas
where the cost of provision is highest thereby offering the major suppliers
overall cost savings.
The Grid Connection
A connection to the national grid will likely be a feature of most
Sustainable Energy Webs. This offers advantages in extra supply to meet peak
demand, a backup supply facility, as well as the option to sell back to the
grid. Peak demand is proportionally relatively high, as are the cost of
supplying it. A design that did not have to meet peak demand would be
significantly less costly. However, it possible that some Sustainable Energy
Webs will not have a grid connection and that they will have to be designed to meet
the peak demand in their location.
Implementation
One of the first steps in implementation would be to establish a small
management team to put together a Development Plan. The team would examine the
best mix of components for a given location and then determine costs and
appraise funding options. This process of creating the Development Plan may
itself require at least a small amount of funding to support the initial
research, site visits and the like.
The implementation of a Sustainable Energy Web would involve bringing
together a number of different types of expertise with a number of
"generalists" to co-ordinate the process. A key element of the development plan would be to establish what
kinds of expertise will be required and where these will be obtained. Expertise
could be very costly and would be best obtained through participation in
suitable research projects. To some extent the technical expertise of reputable
suppliers could be drawn upon to keep such costs down.
It is important for the Development Plan to have some flexibility so
that it can incorporate changes in technology. To this end, the management team
will need to keep apace with such developments so as to be able to maximise the
benefits of any expenditure.
Conclusion
The concept of a Sustainable Energy Web is the natural extension of
various developments taking place in the fields of conservation and energy
generation. It brings together a number of systems to create a more efficient
and effective whole. The basic principles can be applied to different locations
using a variety of different technologies.
Such a system will not only be sustainable from the perspective of
environmental conservation, but will be economically sustainable too as more
efficent usage is made of resources.
Perhaps the field of energy generation will to some extent follow the
development path of computer systems. Initially computer systems were based on
large centralised provision with access being provided to those consuming the
computer resources. However, as we all know, this has largely changed and
computer processing power now tends to be distributed rather than centralised.
It may be that energy generation will evolve similarly and change to being
mostly based on a large number of smaller highly efficient units. It could be
that the National Electrical Grid will evolve into the National Electrical Web
with supply coming from numerous sources. If so, the Sustainable Energy Web
would certainly have a role to play.
William Martin, November 1998.