Page 34 - Energize February 2022

VIEWS AND OPINION

the day, as seen in the well-known California duck curve. Without a requirement would require wind power with a constant output, and
significant amount of BTM storage installed, the night time demand although some countries experience nearly constant wind levels,
pattern remains the same. many systems show wide variation in levels and can drop to very
A second factor affecting demand baseload is storage. Network low levels. The SA wind fleet shows regular straight line transitions
storage can increase demand baseload during low demand periods. between minimum and maximum output level of three to five
BTM storage can increase or decrease demand depending on times, and drops to 2% of capacity.
whether it is charged or discharged. Urban-use EVs which would The development of large scale storage has changed the
most likely be charged during the low demand periods when off picture however, and one could foresee a renewable baseload
road, would increase the demand baseload level. Load shifting and fleet comprising solar and storage, or wind and storage, or both
demand side management can also affect the minimum demand wind and solar with storage. Both of these resources pose one
level. All these factors could affect the DBL level, without affecting problem, in that they are subject to regular periods of low output,
peak demand levels. The effect of this would be to reduce the and dimensioning a system to meet the DBL, even with storage,
amount of fixed load systems that can be used, and increase the under these conditions could be costly and result in underusage and
amount of variable power sources required, increasing the cost of overgeneration during normal resource level periods. Meeting the
generation. Irrespective of all the above, it appears that grid DBL is requirements of the DBL with a varying resource will always result in
not going away and will remain for some time to come. a generation surplus.
There are two ways to handle this - firstly to curtail production
Baseload generation during high generation periods, which means taking wind turbines
Baseload generation (BLG) comprises the systems required to meet or solar panels out of service, a costly process which increases unit
demand baseload, and it is here that most of the disputes are costs. The second method would be to store the surplus energy
focussed. Utilities have traditionally taken advantage of this fixed for later use or use elsewhere. Storing electrical energy has limited
demand, by using fixed output dispatchable power systems running capacity, as it must be reused in the same network, and can only be
continuously at full or close to full load, giving an efficient and used if demand exists. A number of wind/solar/storage solutions
therefore low-cost electrical baseload supply, and these features to the BLG problem have been proposed in the literature, but the
can be taken as the defining characteristic of any BLG system. application seems to be limited to specific locations and cannot be
Identifying the DBL allows the generation fleet to be dimensioned to applied generally
take advantage of this. The realisation that surplus renewable energy can be used
Baseload demand can typically constitute between 30% and to generate green hydrogen, a form of energy which can be
80% of the peak load, depending on the network. More important re-used outside of the electrical network, changes the picture
though is the percentage of total energy generated by base load completely. This may account for the headlong rush into producing
generation, which will be higher than percentage of power, because green hydrogen, and developments of methods to use it in other
of the variable levels of mid-term and peak load. Base load is then industries. This single fact has not only made renewable BLG a
a not-insignificant portion of the generation fleet; a selection of possibility, but has spawned a whole new industry.
systems to fill this sector can have a significant effect on overall The search for a BLG replacement has taken a diversionary
generation costs. turn with the acceptance of nuclear (and natural gas) as “green”
BGL at the moment mostly comprises coal fired and nuclear sources by international bodies, and this has changed the playing
generation, which is fixed output stations that cannot be varied field significantly. Several countries, China amongst them, have
rapidly. The current dispute revolves around whether an equivalent planned to add a significant portion of nuclear to their fleet. China
baseload generation fleet can be provided using carbon free/clean/ is apparently planning to build 140 or more new nuclear power
green technologies. The energy transition requires a move to a stations in the next 15 years. Recent announcements show that
cleaner and greener generation fleet, and the challenge is how to both developing and developed countries are planning to establish
move a significant portion of the generation fleet to an alternative nuclear power fleets or extend existing fleets, either conventional or
technology that offers the same characteristics as the existing the new generation of SMRs.
fleet, i.e., the ability to operate continuously at maximum capacity. Most of these new nuclear plants will used for replacement
Some of the arguments try to avoid the challenge by claiming that of coal fired baseload plant. Faced with a choice of solutions, the
baseload generation is unnecessary. simplest one is often the best, and the choice of large systems with
A first attempt at meeting the challenge was to consider a guaranteed output, would seem to be better than a network
the possibility of an all renewable baseload generation fleet. comprised of many smaller systems with varying outputs.
Hydropower, biomass and geothermal power can all meet the BLG The consensus, among policy makers, and those who are held
requirement, and are being used for BLG in some countries. But responsible for ensuring a safe and reliable supply of electricity,
not many countries have sufficient hydropower, or geothermal or seems to be that a baseload generation fleet is necessary for safe
biomass capacity to meet the DBL capacity requirements, and the and reliable operation of the electric grid, at least for the immediate
choice of renewables is limited to wind and solar power. and foreseeable future, and a replacement for the current fossil
Solar power is a periodically intermittent varying resource, and fuel fired fleet, whatever technology is used, must meet the
on its own could not be used for BLG. Wind energy offers a better basic requirements of security of supply and the ability to deliver
option, as a varying resource, as some wind is always present. electricity at the lowest cost.
The viability of using wind depends, though, on the variation
between peak value and minimum value. To meet the BLG Send your comments to rogerl@nowmedia.co.za

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