Atmospheric carbon dioxide and base-load electricity

Introduction

It is widely believed that the increase in atmospheric CO₂ in the last 250 years (about 200 ppm) is mainly attributable to the burning of fossil fuels since the Industrial Revolution and the evidence is very convincing, especially with carbon isotope data. Whether this increase (0.02% absolute) is causing "global warming" of an amount leading to a catastrophe for humanity in the near future is far more questionable.

"Global warming" (the planet's core is very hot) is probably a politicized term for "surface warming", the latter being a more accurate description. Based solely on this unproven hypothesis that a catastrophe is nigh, the rich developed world, say 10% of the world's population, has decided to abandon the use of fossil fuels without having a proven substitute available with similar cost and reliability characteristics, except for nuclear.

This is risky if nuclear is not considered, it could be costly for these countries, because many other, especially poorer countries, will continue as at present and be more competitive economically, not to mention China.

One the one hand we do not want a global catastrophe nor disrupt natural processes and equilibria, on the other, abandoning cost-effective and reliable sources of energy without it being imminently necessary when there is no equivalent substitute available would be somewhat suicidal behaviour. Determining whether or not CO₂ contributes to significantly and rapidly raising the temperature of the atmosphere is a vital consideration in this context.

Scope

The scope of this paper is to use publically available data and classical physics to review how much anthropogenic carbon dioxide emissions are being contained in, and affecting the atmosphere of the Earth and some of its implications related to the realities of energy generation and consumption issues, divorced from politics, in the real world. The author has no affiliation with the fossil fuel and nuclear industries, the green movement nor any political party and is funded by superannuation.

Distribution of Anthropogenic CO2

Calculated annual increase in anthropogenic atmospheric CO₂ is 36x10⁹/5.2x10¹⁵ = 6.9 ppm which is not accord with the measured increase which presently is approximately 2.5 ppm per year. This would suggest that either the estimate for mass of CO2 in the atmosphere is too low, the estimate of annual anthropogenic emissions is too high or, more likely, the CO₂ is being removed from the atmosphere by processes such as photosynthesis, increasing atmospheric O₂ content, and dissolution in the oceans, reducing pH and creating carbonaceous sediments or some combinations of these. Approximately 40% (2.5/6.9) of annual anthropogenic emissions are being retained in the atmosphere at present.

Annual Production of Heat by Anthropogenic CO₂ Combustion

Annual anthropogenic heat produced = 36x10¹⁵ x393.5 kJ/44=322x10¹⁵ kJ

Annual equivalent atmospheric temperature rise = 322x10¹⁵/0.70x5.2x10¹⁸ = 88x10^-3 = 0.088 or approximately 0.1 Celsius or Kelvin degrees.

Some of this heat will be absorbed by the oceans. Given the enormous mass and high specific heat of the oceans, there will be a long lag time for temperature to rise. This indicates that the annual anthropogenic derived combustion of CO₂ has a minor effect on atmospheric heating but it is cumulative, year on year and as emissions increase so does its effect.

The Earth's Energy Balance and Emission Windows

There is a constant flow of energy from the Sun to Earth and from the Earth to Space, resulting in a steady state energy flow balance at equilibrium. At steady state equilibrium there is an equal amount of energy arriving from the Sun as is leaving the planet, albeit with different spectral values, the radiation emitted by Earth being of longer wavelengths than that emitted by the Sun (Stefan-Boltzman) due to the lower temperature of the Earth compared to the Sun.

The atmosphere is essentially transparent to incoming solar radiation while it is partly opaque to the outgoing longwave radiation (OLR) due to absorption at these longer wavelengths by minor gases in the atmosphere. This absorption causes the atmosphere to be warmer than it otherwise would be (the Greenhouse Effect). Water vapour is the principal source of the absorption. Other minor gases involved are CO₂, CH₄ and O₃. For water vapour there is a particularly good transparent window approximately between 8 and 14 µm. CO₂ has its highest absorption finger around the higher wavelengths of this window, around 15 µm.

Although this steady state energy balance obeys the basic laws of physics and is easy to understand, the actual internals of the system itself are seriously complex. To name a few: the incident solar radiation is subject to a 24 hour cycle, the angle of incidence of the solar radiation varies from perpendicular near the Equator to essentially zero at the Poles, there are discernible layers of the atmosphere, the complex role of H₂O in its various states (ice, water and vapour) and there are oceanic and terrestrial surfaces and circulations and possible feedback loops.

CO2 and the Outgoing Longwave Radiation (OLR)

Carbon dioxide has strong absorption around 15µm wavelength of EM radiation (infrared). Spectrophotometry of the outgoing longwave radiation (OLR) from the Earth from such as the Mars Global Surveyor Spacecraft at a distance of 4.8x10⁶ km from Earth shows the deviation from the thermal radiation emitting curve due to this absorption, indicating that atmospheric CO₂ causes heating.

The 15 µm band is absorbed in less than 10 m from the surface (1/0.095) and at the tropopause it is absorbed in less than 27 m (1/0.038).

On being absorbed the energy is then partly re-radiated in all directions as well as by conduction and convection. At a far enough distance away from the surface the 15 µm band can escape when the pressure and therefore concentration of CO₂ is low enough, giving rise to the characteristic OLR of the Earth with a big deviation around 15 µm area. This follows from the First Law of Thermodynamics and Reciprocity between absorption and emitted wavelengths. The intensity of this radiation will depend upon the temperature at the emission layer (Stefan-Boltzman).

The Earth's OLR may be seen as a 'summary' or end result of all the complex known and unknown thermodynamic processes that occur on the Earth's surface and has the utility and certainty of being a direct measurement.

By comparing the area under the complete body curve to the area deviation by CO₂ at 15 µm, from the spectrograph from the Mars Global Surveyor Spacecraft, a calculated figure of 8.5% contribution to the Greenhouse effect can be attributed to CO₂. Given that CO₂ has approximately doubled since the Industrial Revolution, then 4.25% can be considered anthropogenic. If we assume Earth surface temperature would be -18⁰ C without Greenhouse and now it is 15⁰ C (33⁰ C the difference) then 0.0425x33=1.40 C increase in temperature, so approximately 1.5 degrees C can be attributed to anthropogenic causes.

However the mass and specific heat of the oceans are gigantic compared to that of the atmosphere Ratio of heat capacity of ocean to atmosphere 1.35x10¹⁸ x3.850/5.2x10¹⁵ x0.70 = 1,428 so that it will take a long time to reach equilibrium at the 1.5 C figure as the ocean acts a heat sink. However changes to climate can possibly emerge earlier as the thermodynamic equilibrium of the surface of the planet is being disturbed. As well, unfortunately anthropogenic CO₂ will not stay stationary at the present level without cessation of emissions and so, as time goes on, the temperature rise will be even greater if there are no significant reductions in emissions forthcoming and it would be cumulative.

Energy Economics

Cheap and reliable energy underlies our standard of living. We have fossil fuels and nuclear with nuclear fusion still in research (nuclear fusion does not create the dangerous waste of fission but controlling the reaction has not yet been achieved). In the past cheap energy was provided by slaves and horses, like the Egyptians, the Romans and others used. Intermittent renewables have niche markets but as yet don't adequately replace fossil nor nuclear for baseload, despite the political rhetoric, on the basis of their unreliability (vagaries of the weather) and the lack of economically viable large-scale storage. Development of economically viable large-scale storage of electricity, if or when it occurs, would be a game changer.

The last time we had significant inflation was due to the oil price shocks of the 1970s. We are now facing significant hikes in energy prices for a variety of reasons, including the phasing out of coal-fired power stations and a policy of replacing them with energy from renewable sources. It is unfounded misinformation to glibly say that renewables are an adequate replacement for fossil fuels for base-load power when there is no clear evidence to support this assertion. Although the evidence is strong that there is an anthropogenic contribution to accumulation of CO₂ in the atmosphere leading to atmospheric heating, the increase would appear not large enough to be leading to a catastrophe in the near future but nevertheless large scale emissions do need to be reduced without delay and eventually halted. The phasing out of petroleum power will increase the demand for electricity. Changeover to electric vehicles would significantly increase demand for electricity.

Some Implications

Phasing out fossil fuels is essential but let us do it in a timely and sensible way and replace them with cheap and reliable generation sources when found. Nuclear is the only option at the present time for large scale cheap, reliable baseload electricity generation without increasing the potentially dangerous anthropogenic carbon dioxide emissions on the surface of the planet.

Australia is not in a good relative position. We have made nuclear illegal and it is the only real replacement option for reliable base-load generation available at this time. We have not made provision for a change in base-load electricity generation for when the ageing coal-fired power stations are no longer operational. To build a significant base-load generation plant of whatever kind optimistically takes 5 years and we are not preparing for this, while phasing out coal-fired generators. Solar and wind power have their niche markets but until large-scale storage becomes a viable economic option they are not suitable for base-load power.

The main implication of this is that Australia, with its focus now on wind and solar will have expensive and somewhat unreliable electricity during the next decade and beyond. This will in turn reduce our standard of living and our competitiveness in the global market as well as the real possibility of residential blackouts during peak loads. It should also be noted that most solar panels are made in China and we need to reduce our dependence on that country for strategic goods, such as in the construction of electricity generating infrastructure.

Discussion

Cheap and reliable energy underpins our standard of living. Large scale CO₂ emissions make a contribution to surface warming of the planet. Although there seems no reason to panic about an immediate atmospheric catastrophe it is still necessary to reduce and even eliminate CO₂ emissions and not disturb natural processes.

However, unless there is a concerted global move in this direction, the effort will be wasted if a significant part of the world population does not contribute and instead continues emitting CO₂ unconstrained. There are no national boundaries for national CO₂ emissions in the atmosphere. Any CO₂ emitted from anywhere becomes a part of the CO₂ in a shared atmosphere.

Developing energy technologies to replace fossil and developing nuclear, while limiting carbon emissions, should be a priority and in the meantime, using nuclear generation is an option.

Whatever changes are in motion in the weather, it must be remembered that there is nothing magical or permanent about the complex present dynamic state of equilibrium of our planet's atmosphere, whether we like it or not. It is a common misconception that climate will remain constant if not for us. It is fundamentally unstable as volcanic eruptions and mass extinction of species has shown. Sea levels have changed even in human history. The climate has been changing for the last 4,500 million years or ever since the Earth became a separate entity and will continue to do so with our without human intervention. The environment in which we live is a very complex dynamic system of equilibrium and our understanding of it is far from complete, although we have advanced a lot since when we believed the Earth was flat.

It should be remembered that CO₂ is a vital ingredient in our survival, without CO₂ as an input to photosynthesis there is no O₂ and therefore no life as we know it. Photosynthesis, where CO₂, water and solar energy are converted into glucose and free oxygen allows us to live. Free oxygen is unusual in the Universe due to its chemical reactivity as can be seen in bushfires. The combustion in bushfires is release of solar energy that had been stored in plant matter but without O₂ there is no combustion. Photosynthesis: 6CO₂ +6H₂O+solar---àC₆ H₁₂O₆+6O₂. Without O₂ we all die. CO₂ as input to photosynthesis is a life-giver, not so much a disaster for humanity so long as we eliminate large scale emissions.

If the weather is changing we should look for more causes other than just CO₂ and CH₄. There may be causes over which we have no control and haven't yet identified. For example, the Little Ice Age (say 1600 to 1850), an abrupt cooling change in climate geologically speaking, resulted from natural causes, certainly not anthropogenic. This clearly discounts the assertion that natural change in climate only occurs over millennia. We will have to adapt to the changing conditions on the planet as we have always done but also should avoid making negative impacts on the planet that nurtures us.

Conclusions

The burning of fossil fuels is releasing so much CO₂ that its partial accumulation in the atmosphere is causing the surface of the planet to get warmer. Atmospheric CO₂ has approximately doubled since the Industrial Revolution and most of this increase has accumulated since 1950 as the world industrialized. More than half of the emissions caused by humans today is absorbed by land and sea.

The heat of combustion from fossil fuels to form CO₂ is making only a small contribution, but the heat contribution from combustion will keep increasing unless emission are reduced. The main cause of planetary surface heating relating to CO₂ is its strong absorption finger of longwave radiation around 15µm, as is directly observed in the Earth's outgoing longwave radiation (OLR) from Space, retaining heat in the atmosphere.

The world relies on cheap, reliable and essentially base-load electricity generation. Without fossil fuels the only general source of cheap and reliable base-load electricity is nuclear, which has its own dangers. Intermittent renewables are subject to the vagaries of the weather and there is no large-scale economic electricity storage technology available at present. Such technology would be a game changer but there is no certainty about when, if ever, it will be available. What is generally not realized is that coal, nuclear and hydro have 'built in' electrical storage in the form of control over electricity output by control of combustion, reaction rate or flow.

The lack of cheap and reliable energy replacement for energy derived from fossil fuels is a major problem for humanity. In the meantime nuclear can provide a solution, though with its own dangers that are manageable. Australia has no strategy in place, other than hope, (given it has made nuclear illegal), to replace the base-load electricity from ageing coal-fired generators given that some 75% of electricity generation in Australia today is from coal. We do not have the infrastructure in place for life after coal. Windfarms and solar arrays cannot provide reliable baseload power. Given our trajectory, domestic power prices can only remain static or fall with the aid of government subsidies and our standard of living will suffer.