The Cost of Renewable Power: A Survey of Recent Estimates - Green Energy and Efficiency: An Economic Perspective - page 251

Some estimates [ 21 ] put the total world capacity still available at 5 times the
existing installed capacity for large developments, and up to 20 times for small and
medium systems [ 16 ]. This means a total of approximately 80 % of current energy
consumption worldwide, and a much larger amount if only electricity is considered.
This may be judgmental to some extent given that this value is quite dif

cult to
estimate, but it is an indicator that substantial unexploited capacity still remains, and
that sizeable future developments can therefore be expected.
Summarising, hydro power is an old, competitive, mature technology that has
more installed capacity than any other renewable technology, though other tech-
nologies are being deployed at fast rates. At good sites, it is also the cheapest power
generation technology, including all kind of fossil fuels. Moreover, it guarantees
energy independence and security of supply. It has very good dispatchable capa-
bilities at low or zero cost, and there is considerable capacity still available
worldwide. It is an easily scalable technology, which makes it suitable for tradi-
tional centralised systems as well as for distributed generation and off-grid systems.
Given all of these excellent properties and the large unexploited capacity still
available around the world, substantial further deployment can be expected. Since
the technology is already mature and competitive, no signi

cant cost reductions are
expected, and costs may even increase in countries where the best sites have already
been exploited.
In spite of all these excellent properties, a word of caution must be said on the
possible impact of climate change, given that changes in the weather and in other
more permanent climate features may result in substantial decreases in rainfall, thus
reducing water resources at previously good, developed sites [ 36 ]. This is an open
question that will require close, careful attention in the near future.

3.5 Biomass Power

One of the main characteristics of biomass power generation is the large variety of
power systems and fuel feedstocks that can be used as generating technologies. The
costs and other relevant data therefore vary considerably, so there are no long
historical series available for use in drawing conclusions on general patterns [ 19 ].
As of today, at least three technologies are mature and in some cases commercially
competitive: stoker-boiler direct combustion (which accounts for 80 90 % of all

-

systems worldwide); combined heat and power (CHP); and co- ring

refers to the combination of biomass combustion with fuels of other types. This
usually means coal or oil, though recently combination with CSP systems has been
tried, thus increasing the dispatchable capabilities of that solar technology. Com-
bined Heat and Power systems are especially useful at small to medium sizes, and
may be a good support for the in-house power generation and consumption mode.
The variety of potential feedstocks is also large, which has a strong impact on

ring. Co-

the nal competitiveness of the system. Perhaps the only general point about them

is that they must be generated relatively near to combustion plants, since otherwise