Electricity in perspective

Reliable and affordable electricity is an expectation of society today.  To be fit for purpose an electricity supply system must meet demand as it varies over time as well as being affordable.  Capacity of the system is determined by peak demand.  A highly desirable attribute of any such system is that it keeps total environmental damage to a minimum.

The stand-out item of environmental damage is the so-called ‘global warming’ which is an inaccurate term for ‘global surface warming’.  It seems now beyond question that the accumulation of CO₂ in the atmosphere due to the combustion of fossil fuels and the rate of accumulation and rate of warming are increasing.  However, the lag time for changes in climate due to this anthropogenic cause of warming and the extent of the effect on humanity are not so well understood.  The oceans have a gigantic heat capacity compared to the atmosphere. It is this perceived threat that has led to the frantic rush to move away from fossil fuels to alternative, renewable electricity generation methods by the more advanced economies without pilot plants studies to gather data and to assess the economic and technological limitations of renewables before full-scale investment.

The principal renewables, wind and solar, are seen by many through rose coloured glasses.  The mining of coal and gas, the disposal of the waste of combustion or spent fuel (particularly nuclear) and the rehabilitation of mining and generation facility sites are well understood as environmental damage.  However, the proponents of renewables forget that renewables cause environmental damage too.  Not only do they take up a lot of land to capture energy, materials have to be mined to construct the facilities and then there is the issue of the disposal of waste at the end of life of the facilities, particularly the disposal of used solar panels, which is already causing landfill problems. With the ever-increasing world population the provision of electricity must cause more environmental damage in any event.

The literature abounds with claims by the proponents of both renewables and nuclear that they are cheaper than the other.  Full costs must be taken into account for any meaningful comparison. Comparing generating methods effectively requires data gained from pilot or full scale facilities.  It is difficult to take any of this seriously unless the underlying assumptions are transparent and that the methodology is sound.  Levelized Cost of Electricity (LCOE) is the metric mostly used.  It is becoming apparent that this methodology is inadequate when applied to intermittent renewables such as solar and wind.  Fossil and nuclear are able to adjust to change in demand whereas intermittent renewables cannot and are subject to the vagaries of the weather.  Intermittent renewables cannot adjust to changing demand and so their energy output is only for part of the time and is not so valuable if it has to be stored or lost.  This raises the real cost of useful electricity from renewables very significantly. 

There are only two ways to get around this limitation in renewables.  One is to use alternatives not subject to the vagaries of the weather for base load, peak load, and when the renewables do not generate, that is, a mix of generating types. The other is to have massive storage and capacity able to supply when the weather does not allow renewables to work.  At this time no economic large-scale storage is available and there is no guarantee that it will happen in the near future, if at all. Even if such large-scale storage became economically viable in itself, there is another barrier.  Solar only works for about 4 hours a day on average; it difficult to put a figure on wind which is more dependent on location and wind strength.  In any case, to charge storage batteries, additional solar arrays and wind turbines would be necessary massively increasing the real (capital) cost of electricity by renewables. This is because while not operating these facilities are on standby……they are not utilized 24/7, but they still have to be built…capital cost must be taken into consideration for total cost. It is clear that normal LCOE consideration do not apply.  Comparing fossil and nuclear on the one hand to renewables on the other is like comparing apples and oranges.

Clearly a stand-alone renewables generating facility is not fit for purpose, due to the low utilization factors and high costs of storage. It is conceivable that a combination of solar and wind could provide 24/7 electricity but the standby costs, due to the low utilization of capacity would render the system unaffordable. It could only be fit for purpose if it were part of a mix of generating types where the other type or types are independent of the vagaries of the weather.  Yet, in Australia, billions of dollars are being spent on wind and solar and transmission facilities without regard to cost and  without a supply guarantee for when the weather is not as desired. Our present energy policy is very risky and the proponents are likely to be gone when the costs of electricity may become unaffordable and unreliable. The taxpayer is vulnerable.

A rational approach would be to appraise both renewables and nuclear and their partnership.  Even if the battery economics problem were solved, renewables would still have unaffordable costs, as stand-alone, as perhaps up to 5 times the generating capacity would be required in order to charge the batteries when the weather was favourable, (assuming that the output in 4 hours (for solar) was equal to the average requirement over the day for 4 hours, 24/4 = 6, then the array would need to be increased by 5 times more to gain enough electricity for the day) that is, a capacity utilization factor of 1/6 = 0.17. It is difficult to see how this could be an economic proposition especially when the cost of the batteries (expensive) is added on to the cost of a much larger array. The capacity utilization factor for wind turbines is more difficult to quantify indicatively than solar, being dependent on location and variable wind strength but the same issues arise as with solar.

In summary, low utilization of capacity dictated by the vagaries of the weather makes stand-alone intermittent renewable electricity generating facilities unattractive both on the basis of capital cost and reliability.  Even though wind turbines can work at night, there is no guarantee that a stand-alone system of solar and wind can supply electricity 24/7 without enormous stand-by capacity.

Assessing the potential of a mixture of different generating types, and acting on the data obtained, is the way for the future, from the perspective of net-zero, affordability and minimal environmental damage.  Ignoring technological reality risks putting the economy, and the well-being of us all, at risk