Innovation in Global Power - Parsons Brinckerhoff

Hydropower – New Technologies, New Considerations
disadvantage, however, particularly in larger sizes, where
they can cause large variations in voltage and power factor
on the local network. For this reason, the network owner may
have rules about the maximum size of induction generators
allowed to connect, and require power factor correction.
Technical and Economic Feasibility
Once a concept design has been completed and the
transmission aspect investigated, the engineer can confirm
whether the scheme is technically feasible. Next should
follow the consideration of economic feasibility. We strongly
recommend that an engineer prepares the first cut of this
analysis given that engineering knowledge is important to the
application of the costs in the analysis. In addition, the analysis
process provides important feedback to the engineer on
the design, and may force a rethinking of some aspects of
the project.
PB has recently undertaken a scoping study for Tillegra Dam
in New South Wales, Australia, to determine what options
are available to recover energy from the environmental flow
discharge. This study has shown that the environmental flow
can be accommodated by a small hydro turbine for minimal
project cost (comparatively speaking); however, a larger turbine
may also be justified to recover energy from some of the
water that would otherwise be spilled past the dam in periods
of high lake inflows.
Specifications and Conditions of Contract
Specifications should be written by someone who is well
experienced in hydro and understands what information is
required by the tenderers. There is much to be considered
in the detail that is beyond the scope of this article; however,
a few key decisions should be made before beginning.
Q and A
Question:
Would a smaller unit be
sourced as a package?
John Wichall, Senior Consultant,
PB Network Guest Technical Reviewer
Answer:
This is often the case, although
for a recent 250kW unit
the utility preferred a
particular supplier and could
buy the generator
(a Siemens product)
for significantly less money
than the supplier’s
chosen brand.
The first choice is to decide
how the equipment will be
supplied. This includes
decisions on whether:
• The turbine and generator
will be separate packages
and matched together
at site
• The control and auxiliary
systems will be included
with turbine or generator
or be a completely
separate package
• The contract will be an
equipment supply, or
supply and install, or supply
and supervision type.
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Conditions of contract cause many an engineer to run for cover.
For the value of the contracts considered here, standardised
conditions such as those within the International Federation
of Consulting Engineers (FIDIC) or the joint IMechE/IEE
Committee Model Forms of General Conditions of Contract
(e.g., MF1 or MF2) should be used. It is strongly recommended
that no modifications be made to the standard conditions,
and that any particular issues be covered only in the special
conditions. The special conditions should cover penalties for
non-performance and must be reasonable, otherwise they will
adversely impact the tendered prices.
Overall the commercial conditions should not substantially
outweigh the technical specifications. A lightweight specification
will not be fixed by heavy-handed commercial clauses and
general ignorance of the requirements for a successful mini hydro.
In the last year, we completed the technical specification for
the turbine and generator for the Gippsland Water Factory
in Victoria, Australia. 1 The turbine will replace a pressure
reducing valve that is currently used to dissipate the energy
in the raw water supply before returning it to a reservoir.
This project is an example of how existing infrastructure can
be modified at relatively low cost to capture the otherwise
wasted energy and convert it to electricity. Some of the
generated energy is then used at the nearby water factory.
When completed, this project will provide a sustainable energy
source that will reduce energy costs at the facility and, in the
long run, will benefit the community.
Tenders and Tender Evaluation
Tenderers must be given sufficient time to write their
tenders. This should be a minimum of one month for small
jobs, and up to several months for more complex jobs,
such as those requiring civil works or the supply and install
of the entire scheme.
We believe economising on the turbine/generator set is unwise.
As with most electromechanical equipment, increased quality
and efficiency is matched by increased price. There are some
very good manufacturers who maintain the latest in computational
fluid dynamics (CFD) programs and hydraulic test
programs. In general, their equipment will be more efficient
then that produced by manufacturers with less sophisticated
design and equipment. Economic analysis of the capital and
life time operating costs, as mentioned earlier, is essential to
discern whether additional revenue from higher efficiency
and reliability is compensated by the higher capital cost.
Readers are warned to beware of suppliers claiming efficiency
in the top of the range that large turbines typically
(page 37)
1 To learn more about the Gippsland Water Factory, see "Water Factory Will Help
to Address Water Shortage Concerns" by Tony Mulholland, pp.94-95.
PB Network #68 / August 2008 26