Baseload power in a renewable environment

Baseload power should be reconsidered in the light of the recent blackouts in Texas. While storage can do much to reduce the frequency of blackouts, storage is limited by the electricity that has been already “stored” in either batteries or via pumped-hydro.

The primary role of batteries is to manage the difference between supply and demand for electricity during the day. If the surplus supply is greater than the capacity of the batteries, the surplus can be diverted to pumped-hydro facilities, if available. These can be configured to provide much greater electricity “storage” capacity.

In the event that demand exceeds supply over many successive days, it is possible that both batteries and pumped-hydro dams will be emptied. In this case, blackouts have just been deferred for those initial days and not avoided for the whole period. A baseload power strategy is required to reduce the possibility of a catastrophic failure of electricity supply during an unusual climate event.

How much baseload power is required?

The maximum quantum of baseload power required is the maximum unavoidable demand. This is equal to the maximum demand at any time at day or night less the demand that can be cut off by fiat of the regulator, or by negotiation with business. Things that can be planned to be shut off include:

• Aluminium and steel works can be put into standby mode provided sufficient warning is provided.
• Domestic and business use of electricity can be scheduled to be shut down in different suburbs and towns at different towns for a short time in order to reduce the peak load.
• Certain usages can be banned, depending on the predicted willingness of individual users to comply. For example, cooking the evening meal could be postponed until a later hour or brought forward. In a country like Australia, this would not be welcomed but compliance is likely to be widespread. (For the impact of the 6 pm peak see this analysis done a few years ago for South Australia.)

There will be political price to pay for any requirement to reduce demand for electricity, but there will also be a political price to pay if the cost of more baseload power is more than necessary. It is a matter of balancing costs and risks.

Renewables will still contribute to power in a crisis

It is not possible to guarantee that renewables can supply any level of electricity, but the reasonable probability of renewables being able supply a certain level of power can be calculated. The likelihood of an unusual climate event significantly causing the electrical “storage” system to be exhausted will be reduced wherever there is a wide distribution of renewable energy resources. In Australia, this could encompass all the east coast states plus South Australia. The chance of an unusual climate event having the same impact everywhere is almost zero, but some effect can always be expected.

In calculating the quantum of power that can be sourced from renewables in an extended climate-change crisis one must realistically consider impact of such an event if it happened and consider the probability of such an event, say in the next thirty years. This is a matter for engineers and statisticians to consider.

These calculations will not be easy, but they can be done. Once completed, a reduced maximum quantum of baseload power outside the renewable sector can be calculated.

Gas-fired electricity generators can be used

Even though this conflicts with the idea of “net zero” emissions, there can still be a case for at least 10% of the current use of natural gas to be continued into the future while still holding firm to the target that temperature increase since industrialisation are to be held at 1.5C.

The advantage of continuing to use gas-fired electricity generators for peaking electricity demand is that if an unusual climate event happens that leads to electricity supply being curtailed, the peaking-demand generators can be turned on in off-peak times in order to generate electricity to meet the demand and, if possible, to replenish the electricity “storage”.

The electricity that can be supplied by gas-fired electricity in this crisis will also reduce the calculated maximum quantum of baseload power that is required outside of renewable resources.

Meeting the final baseload power requirement

There are three available methods of providing baseload power:

1. Electricity from biomass.
2. Electricity from geothermal resources.
3. Electricity from nuclear power.

The downside of burning biomass is the possible negative environment impact of doing this on a large scale.

Geothermal resources, deep underground, provide an excellent means of providing a constant supply of electricity with virtually no environmental impact (even though a project near the Cooper Basin in South Australia was abandoned because it was not economic at the time). Under the scenario considered here, the electricity produced from geothermal sources could be immediately stored and dispatched as required.

Nuclear energy needs to find a new spot in the world’s electricity network. To do this it will be necessary for its advocates to increase the community’s confidence in the long-term safety of nuclear-powered electricity generation. This could be possible via the smaller modular nuclear molten-salt reactors that are currently being considered.

Final baseload power requirement

Using the Australian National Energy Market as a guide, let us try some rough numbers to calculate a safe capacity:

• Peak demand capacity: 2019-20: 35,626 MW.
• Measures to manage demand reduced anticipated peak demand in a climate-related demand crisis by, say, 25%.
• Geothermal contributes, say, 6% to supply by continuous running = 1318 MW (running 24 hours operation 365 days = 11.55 TWh out of 192.4 TWh).
• Assume gas-fired peaking capacity (for 1 hour a day) contributes 5% to peak supply to help meet demand = 1,781 MW.

We now move to model total electricity demand per day in a climate-related demand crisis:

• Total electricity demand in a year = 192.4 TWh
• Daily electricity demand in a day less 25% = 395,000 MWh
• Demand that is met by peaking capacity = 1,781 MWh
• Additional capacity from peaking = 40,963 MWh
• Daily demand met by geothermal = 31,632 MWh
• (Normal demand met by wind and solar renewables = 493,000 MWh)
• Daily demand met by renewables at 25% (assuming storage has been exhausted) = 123,250 MWh
• Net demand to be met by other baseload capacity = 197,394 MWh.

If the other baseload capacity to meet this situation was able to run 24 hours a day, the installed baseload capacity would need to be 10,000 MW (including a 25% contingency). This represents about 30% of peak demand. If a climate-related crisis is expected to result in increased demand, this will need to be taken into account by providing additional baseload power.

Conclusion

On this indicative numbering, electricity from intermittent sources like wind and solar should, on average, be less than 70% of supply. This can be managed by contracting the above pure baseload generators at a fixed price with a guarantee that these generators will meet the available demand before any intermittent supply is taken up. Unless intermittent sources are subjected to this kind of control, baseload power sources will atrophy and close due to lack of use. Therefore, they will not be available when they are needed.

Of course, these numbers are only an indicative example, with other factors to be included as required, but they do show that 100% renewables could bring problems in its wake.

If the first-call use of baseload capacity is not maintained the whole system is likely to become unstable, leading to serious problems in the supply of electricity to those who desperately need it.