The Weekly Carboholic: nuclear energy is not zero-carbon, but is low carbon

Posted on October 1, 2008



Nuclear power is not, as the industry and some politicians claim, a carbon-free source of electricity. It is truly carbon free when you split uranium in a nuclear fission reaction, but acquiring that uranium-235 and disposing of its wastes are not zero-carbon enterprises. For that matter, nor is constructing the nuclear power plant itself. And now Nature News has reported on a study about how much carbon nuclear power plants emit over their entire life cycle, and the life cycle of its uranium fuel.

The study claims nuclear power emits between 1.4 g carbon dioxide equivalent per kilowatt-hour (gCO2e/kWh) and 288 gCO2e/kWh, with an approximate mean of 66 gCO2e/kWh. This compares quite favorably in even the worst case (288 gCO2e/kWh) to scrubbed coal’s 960 gCO2e/kWh or natural gas’ 443 gCO2e/kWh, but not as good as photovoltaic or onshore wind, at 32 gCO2e/kWh and 10 gCO2e/kWh respectively. But even at 66 gCO2e/kWh, nuclear appears to be a truly low carbon electricity source, although not a carbon-free source.

Representatives from both anti-nuclear environmental groups and a pro-nuclear industry group dislike some of the basic conclusions of the study. The environmental groups dislike that nuclear has significant proliferation issues, faces questions about the sustainability of the uranium supply, and is publicly supported via government tax subsidies against standard free market determinations of value. And the nuclear industry group points out that environmentalists are pushing for tax subsidies for their favored renewable technologies and that renewable electricity cannot provide baseload (always on electricity that’s tunable moment-by-moment) electricity supply. However, the study pointed out that money spent on renewable electricity generation or energy efficiency will prevent the emission of great deal more carbon than even nuclear will.

Perhaps the best approach is what PCAP’s Bill Becker suggested in his interview during the DNC, but that both the environmental groups and the nuclear industry seem to be unwilling to accept at this time:

[W]e don’t oppose coal, we don’t oppose nuclear. We oppose carbon emissions, we oppose proliferation. What we need to do as a nation is set a performance standard for the technologies we’re going to promote and subsidize publicly. We need to meet this standard for net energy gain, net carbon reduction, national security impact, water consumption.


Global heating may cause ocean dead zones
There are dead zones – areas where normal ocean life has died due to a lack of dissolved oxygen in the water – scattered throughout the world’s oceans, and the number and size of the dead zones are increasing. Most dead zones have the same cause as the well documented and understood Gulf of Mexico dead zone at the mouth of the Mississippi River, namely runoff of phosphorus and nitrogen compounds into rivers that causes an algal boom in the ocean. When the algal bloom dies, the decomposition of all that organic matter uses the oxygen dissolved in the water, making an area where normal life cannot survive but where sulfur-eating anerobic bacteria can thrive and create toxic sulfur compounds that kills any organisms that cannot flee and that poisons the area for weeks or months. But the algal bloom-dead zone cycle isn’t inherently driven by agricultural runoff or human wastes being dumped into rivers – anywhere that theres a sudden increase in the amount of nutrients available to algae at the ocean’s surface can produce a dead zone. And it now appears that global heating, as it changes the location and strength of ocean currents and nutrient-rich upwellings, may create dead zones as well, such as the recent dead zone off the coast of Oregon.

According to the Scientific American article, Andrew Bakun of the University of Miami believes he knows why some of the dead zones are appearing so close to shore in places where they never used to appear: global heating is increasing the temperature difference between the ocean and the land. The increased temperature difference drives coastal winds, and it’s these winds that are largely responsible for creating upwellings as the wind blows surface water back out to sea and uncovers nutrient-rich deep water. More nutrients means more organic matter to decompose and lower oxygen levels.

Unfortunately, there’s not a lot of data on upwelling-driven dead zones – they’re too new – and so scientists don’t really know for sure, but the hypothesis fits the existing facts so far. This means that scientists don’t have enough data right now to predict when changes in upwellings might kill off a commercially important fishery as a result of global heating. Apparently overfishing and ocean acidification weren’t bad enough problems.


Livestock may help increase soil carbon
It’s not every day that you come across someone suggesting that livestock, usually put in the column titled “this is bad for the climate”, could well be the key to adding carbon to our soils world wide and, in the process, pulling the carbon that’s already in the atmosphere out and improving soil yields and water management in the process. Yet that’s exactly what Soil Carbon of Bond University, Queensland, Australia is suggesting. And after reviewing their case study (English version), I have to say that their proposal at least makes some logical sense.

The gist of the situation is this – insufficient management of livestock has led to the wholesale destruction of large areas of otherwise productive land. When livestock are managed properly – driven from one part of the range to another to prevent overgrazing, populations controlled, and so on – the livestock can actually enhance the quality of the land they’re ranched on. The reason is that livestock leave fertilizer around, punch seeds into hard packed land, and thus give new plants a better chance to grow with more nutrients and better access to water. And so long as the livestock are kept moving through the recovery areas, the land will eventually grow more lush and, at the same time, sequester more atmospheric carbon.

In essence, livestock are used as a recovery tool for damaged agricultural lands and, because the amount of plant life increases, more carbon is stored in the land and water soaks into the land instead of running off in flash floods.

The photos are pretty amazing and compelling, and the case study document is well worth the 15 minutes it’ll take to read.


New international study on green job creation
Last Saturday, Green Jobs Now held their National Day of Action where over 700 events held in every state showed local communities that there were jobs to be had in the “green” sector. In the last week, a new report produced by the International Labor Organization, the U.N. Environment Program, and the International Organization of Employers and reported by Voice of America found that 2.3 million green jobs had already been created in renewable energy and that another 8.5 million green jobs would be created by 2030 in just solar and wind power. In addition, the report found that renewable energy was currently generating more new jobs worldwide than fossil fuels.

If you read the summary of the actual report, you find that the news is actually much better than the VOA article suggests. The growth in renewable energy from 2006 (~2.3 million jobs) to 2030 is 18 million more jobs world wide, while the full report says that millions to tens of millions of jobs would be created in green buildings, a net gain of about 600,00 new jobs in green transportation (after subtracting the lost jobs in dirty transportation), but an unknown number of new jobs in organic and natural agriculture, sustainable forestry, and green industry. And while the green sector is expected to grow from about $1.4 trillion today to $2.3 trillion by 2020, the growth will not occur equally everywhere, for all job categories, and in equally green ways – some areas will grow more than others, some may in fact shrink, and some jobs are simply less green than others.

The key to all of this tremendous job growth is education and training. New employees need to be taught how to work in a green fashion within existing industries, existing employees need to be similarly trained, and those people who lose their jobs due to a green transition need to be retrained how to do a new, green job (or shown how to do their old job for green contractors).


Combined photovoltaic and solar thermal technology
Green, Inc., one of the many NYTimes blogs, reported on a brilliant new development in solar energy – combined photovoltaic and solar thermal panels.

Photovoltaic panels produce electricity from sunlight, but they aren’t very efficient partly because of how much energy is converted to unrecoverable heat. Solar thermal panels use sunlight to create heat specifically to function as a hot water heater or to directly heat the home’s air in lieu of a furnace. The new system by Berkeley-base PVT Solar uses the fact that so much of the sunlight is converted into heat even in photovoltaic systems to simultaneously generate electricity and provide heating to the house’s water or air. In addition, because electronics in general run more efficiently when cool instead of hot, the solar thermal aspects of the new system also cools the photovoltaic panels themselves, making them more efficient.

The Green, Inc. post quotes Gordon Handelsman, president of PVT Solar as saying “We make around 100 percent more energy than a regular PV system.” Given that this “combined-cycle” solar energy system is more than 50% energy efficient, it’s hardly a surprise that Vinod Khosla, the company’s primary investor, say “[n]ow the economics make sense.”

One way to tell that an idea was brilliant – it looks glaringly obvious and self-evident after the fact. I hope that it works, and that PVT Solar makes millions, if not billions, licensing the technology far and wide.

Image credit:
Soil Carbon

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