Nuclear energy - a much vexed question

Source: World Nuclear Association

The question of the use of nuclear power continues to be a central issue of debate particularly given the increasing share of power generation which the sector continues to grow and the need to reduce and finally remove reliance on fossil fuel consumption (oil and coal).

The industry points out that clean electricity from 'new renewables' (viz solar, wind, biomass and geothermal power) has the capacity to produce electricity in the decades ahead only in  limited amount. The International Energy Agency projects that, even with continued subsidy and research support, these new renewables can only provide around 6% of world electricity by 2030. That is actually a questionable figure and quotation as currently, in some economies, 6% or close to it has already been reached.

Further the industry argues that while environmentalists have played a valuable role in warning that catastrophic climate change is a real and imminent danger, it is also crucially important that they be equally realistic about solutions. Even with maximum conservation - and a landscape covered by solar panels and windmills - the world's community would still need large-scale source of around-the-clock electricity to meet much of the world's energy needs. Nuclear power, it is argued - like wind, hydro and solar energy - can generate electricity with no carbon dioxide or other greenhouse gas emissions. The critical difference is that nuclear energy is the only proven option with the capacity to produce vastly expanded supplies of clean electricity on a global scale. 

However this position while on a superficial basis appears accurate, it overlooks a variety of related issues which impact on the nuclear power generation. The cost of waste management and disposal of highly dangerous radioactive waste is not presented nor accounted. The actual cost of power generation per kilowatt is actually more expensive than the dirty coal fired generators and of the different nuclear technologies, only one has a modicum of safety over the long term.

Source: World Nuclear Assocation

Are wind turbines the answer for renewable energy?

Wind Turbine Farm, Bungendore, New South Wales, Australia

An article from New Scientist has raised an interesting question surrounding possible limitations on renewable energy sources other than solar and actually going backward rather than solving one of the critical energy issues.

Axel Kleidon of the Max Planck Institute for Biogeochemistry in Jena, Germany, says that efforts to satisfy a large proportion of our energy needs from the wind and waves will sap a significant proportion of the usable energy available from the sun. In effect, he says, we will be depleting green energy sources. His logic rests on the laws of thermodynamics, which point inescapably to the fact that only a fraction of the solar energy reaching Earth can be exploited to generate energy we can use.When energy from the sun reaches our atmosphere, some of it drives the winds and ocean currents, and evaporates water from the ground, raising it high into the air. Much of the rest is dissipated as heat, which we cannot harness.

At present, humans use only about 1 part in 10,000 of the total energy that comes to Earth from the sun. But this ratio is misleading, Kleidon says. Instead, we should be looking at how much useful energy - called "free" energy in the parlance of thermodynamics - is available from the global system, and our impact on that.

Humans currently use energy at the rate of 47 terawatts (TW) or trillions of watts, mostly by burning fossil fuels and harvesting farmed plants according to Kleidon's calculations. This corresponds to roughly 5 to 10 per cent of the free energy generated by the global system.

"It's hard to put a precise number on the fraction," he says, "but we certainly use more of the free energy than [is used by] all geological processes." In other words, we have a greater effect on Earth's energy balance than all the earthquakes, volcanoes and tectonic plate movements put together.

Like so much of the current research into energy and environmental alternatives, considerable additional data needs to be gathered, but if correct, this model poses a considerable barrier to be overcome if fossil fuel reliance is to be fully replaced by alternative renewable energy sources.

Biofuels - CO2 emissions may increase

One of the key planks in reducing both CO2 emissions and reliance on traditional fossil fuels for energy use has been the development of the biofuel industry as a substitute but how effective is this alternative in reducing greenhouse gas (GHG) emissions ? The European Union has adopted an ambitious target of reducing GHG emissions by 20 % by 2020 including replacement of 10 % of transport fuel with biofuels. However the Institute for European Environment Policy has estimated that 4.1 to 6.9 million hectares of land must be cleared to meet these target which would correspondingly lead to an 80 % to 169 % increase in carbon emissions during the 2011 to 2020 period (than if conventional fossil fuels were retained). The various energy options to replace current fossil fuel consumption are continuously appearing to have greater pitfalls than first thought. The food famine of a few years ago in parts of the World was partly attributable to the conversion of previous food crop land to biofuel crops mainly in South America and served as one example of the complex challenges of reorienting the world to a new reality.

Solar energy has the appeal in Australia

Encouraging news on the uptake of a key alternative renewable energy source:

http://www.smh.com.au/environment/energy-smart/aussies-do-their-bit-as-solar-panel-use-surges-20101221-193q3.html

Nuclear Power and radioactive waste

The environmental community remains split on the virtues or otherwise of the use of nuclear power to replace reliance on coal fired generators. On the positive side, nuclear energy does not produce the level of carbon emissions and greenhouse gases although it does remain reliant on the mining and processing of uranium. On the negative side, it produces highly radioactive waste that remains potent for thousands of years. Around 14 % of the world's electricity is produced from nuclear power plants and around 12,000 tonnes of waste. One theoretical proposal being canvassed in experiments in Europe and Japan is to saturate plutonium, uranium with neutrons which cause the isotopes to become unstable, then decay into material less problematic for disposal. How realistic is this proposal given the number of existing nuclear power stations and those proposed for replacement or new construction? Can the quantity of waste be effectively managed with such a process which in itself carries risks. Any solution which is found to be viable remains decades away and in itself, it is unlikely that nuclear power will produce the trump card to enable a clear removal of fossil fuels for power generation.  

Carbon Emissions - one problem among many

The debate on climate change often focuses on the level of Carbon Emissions (CO2) and global warming but the overall complexity of the earth's environment means there are several other possible serious factors to consider. Some of  these are listed below - 

Acid Oceans: the amount of carbonic acid in the oceans and the loss of aragonite,

Ozone Depletion: this was the environmental issue of the 1970s and remains a current concern as trapping warmer air closer to the surface of the planet means a colder stratosphere and hence ozone comes under threat again from those chemicals still is use which deplete it.

Fresh Water: Water is becoming so scarce in many parts of the planet, despite unseasonal periodic flooding that underground aquifers are being pumped out and cannot be replenished,

Biodiversity: continued mass extinction of species has considerable impact on ecosystems and on human habitation - the current rate of change has far exceeded levels of adapatability,

Nitrogen and Phospherus cycles: agriculture and fertilisers, burning fossil fuels/timber/crops and human sewage have contributed nitrogen in such quantities that dead zones and algae blooms are now more frequent in the oceans,

Aerosol Loading: dust, sulphates and other particles created by human activity continue to affect air quality and hence have a negative impact on agricultural crops and human health,

Chemical pollution: There are almost 100,000 different human made chemicals now in use on the planet among these are toxic heavy metals (such as lead) and persistent organic pollutants (such as DDT, PCBs and dioxins).  These have strong detrimental effects on humans.

Many of these factors are causally linked to each other and only a comprehensive strategy on climate change togther with a wider linkage to other aspects of pollution has any hope of succeeding.

Geothermal energy - a price too high to pay?

From the New York Times, 10 September 2009

The question of harnessing the earth's own capacity for energy generation should be measured against possible other effects and risks as the article below outlines.

LANDAU IN DER PFALZ, Germany — Government officials here are reviewing the safety of a geothermal energy project that scientists say set off an earthquake in mid-August, shaking buildings and frightening many residents of this small city. The geothermal plant, built by Geox, a German energy company, extracts heat by drilling deep into the earth. Advocates of the method say that it could greatly reduce the world’s dependence on fossil fuels by providing a vast supply of renewable energy.


But in recent months, two similar projects have stirred concerns about their safety and their propensity to cause earthquakes. In the United States, the Energy Department is scrutinizing a project in Northern California run by AltaRock Energy to determine if it is safe. (The project was shut down by the company last month because of crippling technical problems.) Another project, in Basel, Switzerland was shut down after it generated earthquakes in 2006 and 2007 and is awaiting the decision of a panel of experts about whether it can resume.

The Landau project will be allowed to continue operating while the review panel, which held its first meeting last Friday, deliberates. Geox officials initially denied any responsibility for the temblor and continue to dispute the government’s data linking the project to the quake. The panel will, among other things, have to sort through the conflicting data presented by the company and government scientists.

Like other earthquakes that have been attributed to geothermal plants, the Landau temblor was sudden and brief and was accompanied by a sound that in some cases has been likened to a sonic boom. There were no injuries and there was no known structural damage to buildings in the city. But the 2.7 magnitude quake has stoked fears and set off debate in the state Parliament, which subsidized the construction of the plant, about the method’s safety.

In interviews last week, Geox officials conceded that the plant had set off tiny earthquakes and said that they were not certain what set off the Aug. 15 temblor. But consultants for the company dispute the data cited by government scientists to back up their conclusion that the project caused the earthquake: their own data, they said, proves that the quake originated more than two miles from the site of the plant and six miles below the earth’s surface. Those figures would essentially rule out a connection with the plant.

The Landau plant, which cost $30 million, went into operation in 2007 and produces electricity for 6,000 homes by drawing heat from beneath the bedrock, nearly two miles beneath the earth’s surface. Geox said a coal-burning plant producing the same electricity would emit 30,000 tons of carbon dioxide annually.
-----------------------

Bubble and Squeak - Methane a new energy source?

With the constant pressure to find alternative energy sources to reduce reliance on environmentally damaging coal fired generators and other fossil fuels, attention has turned to the high concentrations of methane which are found in various countries. In particular methane clathrate has become a favoured possible alternative energy source. Methane clathrate consists of molecules of methane trapped within ice crystals. With an appearance similar to dirty ice and a sorbet-like consistency, the application of heat rapidly ignites methane clathrates which omit about half as much carbon dioxide as burning coal.

Large deposits of methane clathrates can be found throughout the world in Central America, Japan, India, Alaska and Siberia both in permafrost and under the Ocean. The technology for extracting this energy source is still experimental and with methane clathrates lodged in fragile ice crystals, the safety and economic viability is in question. Also the methane molecule is twenty times as powerful as CO2 in warming the air. With rising sea temperatures, it would take little to release ocean clathrate reserves into the atmosphere.