Base load theory

The base load theory is a subject which should be considered in the adoption of intermittent renewable electric power generation.

The issue was discussed in a 2004 paper.

Base load theory argument
First, It has been claimed that the variability of wind and solar are overestimated. Wind can provide some peak capacity credit, and solar is actually much more closely correlated with demand than is nuclear.

This includes an extrapolation from the observation that intermittent energy sources such as the wind or direct sunlight are not continually available at a single site, to the observation that line transmission loss increases with distance in an electricity network. Large amounts of electric power storage require substantial plant and equipment with some related capital and running costs. Statistically, however, these power sources are not fickle but highly predictable. For instance, the energy content of moving masses of air is very consistent over a wide geographical area, so numerous and widespread wind farms do not in aggregate experience the same intermittency as individual turbines.

Second, the argument presumes that renewable energy is predominantly intermittent, whereas most of the renewable energy in use today is in the form of fuel which can be burned on demand, and base-load capable renewable electric generators are common, including biomass geothermal and hydroelectric power. Promising emerging technologies include solar thermal power plants which store the sun's daytime heat for overnight electric generation.

Third, it presumes that the distribution of supply between night-time ("base-load") demand and daytime (peak) for electricity is fixed. This stems partly from a lack of awareness of the extent to which consumption has been moved from the day time to night time by "demand" charges for Industrial/Commercial consumers (aka Demand Side Management, or DSM). This causes an overestimation of the importance of base load power (which typically cannot easily or cheaply reduce output in response to falling demand) which produce more power than would otherwise be required.

This lack of awareness of DSM causes an undestimation of the ability of the grid to handle either wind at night, or solar at peak demand periods.

It must be noted that because of the inherent variability in electric demand, any small contribution from intermittent renewable sources to an existing energy grid can be compensated for as though it were a reduction in the curve of demand from established electric generators. Larger contributions require some occasional and predictable compensation for their variability from peaking or load-following type generators; the additional cost of this compensation is known as a "firming" or "integration" cost. Unless the penetration of intermittent generation into the power supply network is very high (such that intermittent supply regularly exceeds gross electricity demand), any additional contribution that can be made from intermittent fuel-free energy sources has potential environmental and economic benefits due to fuel savings.

Greenhouse gas abatement and integration costs of intermittent electric power generation

The incremental integration cost of adding intermittent electric generation to an existing electricity network depends very much on the existing generation mix and on the correlation of the intermittent energy source with the network's load profile. In many situations the supply profile of wind power correlates so well with the load profile of electric demand in the existing economy that intermittent power mostly displaces power from expensive load following power plants, making the integration cost negative. The same is true for solar electric power, which is most abundant at exactly the same time as electric demand for air conditioning is at its greatest.

A principal motivator for advocacy of renewable energy is in order to reduce net greenhouse gas emissions, but it should be noted that expensive capital investment in new electric generation equipment is not necessarily the cheapest way to achieve this goal.

Load-following and peaking power plants typically use natural gas or hydroelectricity and therefore produce below-average carbon dioxide emissions, so while the economic benefit of intermittent generation is greatest when supply matches the demand curve, the emission reduction benefit is reduced. For intermittent renewables to have a large greenhouse mitigation effect, they must generate enough power to displace inexpensive coal-fired base load power stations, rather than peaking generators.

Even when electricity from fossil fuel is the principal source of carbon dioxide emissions, it may be cheaper to reduce an economy's net emissions by targeting more potent greenhouse gases and by other ways to reduce fossil fuel consumption including urban planning (in order to reduce the demand for transport fuel), cogeneration, end-use efficiency of electric and fuel-burning equipment, fuel substitution and careful management of forestry and agriculture.

The base load fallacy in Australian politics

The fallacy was presented by members of the Australian government in 2004 when it was noted that the Mandatory Renewable Energy Target was working "too well". This has been understood by commentators such as Clive Hamilton of the Australia Institute to mean that the success of renewables jeapordised the government's commitment to lobbyists from industries such as coal, uranium and aluminium., although the decision not to extend the MRET was ostensibly taken on the basis that there were cheaper ways to limit greenhouse gas emissions than by subsidising renewable electricity generation. Subsidies which would have supported immediate renewable energy deployment and the nascent domestic renewable energy industry were diverted to research into clean coal and geosequestration technology. Adoption of such measures has been on an experimental scale only, and Australia's greenhouse gas emissions continue to rise.

Since that time the same Government has decided to increase the nominal target, but expanding it to cover non-renewable "clean energy" technology such as nuclear and clean coal generation as well as renewables. This long-term endorsement of coal and nuclear power is usually accompanied by a repetition of the base load fallacy, even while promoting intermittent renewables in niche markets (such as photovoltaics for daytime air conditioning peak shaving purposes).

On December 10, 2007 Patrick Moore, a co-founder and former leader of Greenpeace, wrote the following, "Greenpeace is deliberately misleading the public into thinking that wind and solar energy, both of which are inherently intermittent and unreliable, can replace baseload power that is continuous and reliable. Only three technologies can produce large amounts of baseload power: fossil fuels, hydroelectric plants and nuclear power. Given that we want to reduce fossil fuels and that potential hydroelectric sites are becoming scarce, nuclear power is the main option... Over the past 10 years, Germany and Denmark have poured billions of taxpayers' euros into wind and solar energy in the vain hope that this would allow them to shut down fossil fuel and nuclear plants. They have not succeeded because every solar panel and every wind turbine must be backed up by reliable power when the sun isn't shining and the wind isn't blowing."
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