Energy Policy and Environmental Choices: Rethinking Nuclear Power

Will the public rethink nuclear power?

I have not posted anything to this blog about pebble bed reactors for months. I have been busy developing a way to educate the general public about the broader issues of nuclear power.

Most people to whom I have presented the pebble bed reactor have been encouraging and supportive. The most common query I receive is "what about the waste?".

I now think public acceptance of nuclear power will depend on reprocessing to burn up the most hazardous radioactive waste. Also, reprocessing will wondrously provide a century of power just from the existing spent fuel inventories at nuclear power plant sites. Not only can non-fissile U-238 be bred into plutonium fuel, but abundant thorium can also be bred into U-233 fuel. We can have fuel that meets all our energy needs for thousands of years and waste that decays in a few hundred.

I have tried to rethink the advantages and disadvantages of pebble bed reactor technology. which I summarize below.

ADVANTAGES

• Passive safety makes core meltdown impossible.
• Modularity allows smaller plants, with less capital investment risk, and distributed siting.
• Small size permits factory mass production and on-site assembly.
• High temperature, air cooled reactor needs no water for cooling.
• 50% efficiency means 2/3 the fuel use.
• High temperature permits direct hydrogen production.
• Multi-layer pebbles containing all reaction waste products are ready for burial.

DISADVANTAGES

• Technology learning curve not yet fully traversed.
• Licensing in the US will require new NRC skills and knowledge.
• US needs more nuclear power now, from already approved designs.
• Fuel supply will be strained at the proposed one-unit-per-week installation schedule.
• Reprocessing fuel in the hard pebbles will be difficult.

DARTMOUTH COLLEGE ILEAD
ENERGY POLICY AND ENVIRONMENTAL CHOICES:
RETHINKING NUCLEAR POWER

This is an 8-week course developed for the Dartmouth Ilead continuing education department. The course meets 2 hours a week beginning March 31, 2008, at Dartmouth College in Hanover NH. More information is available at http://rethinkingnuclearpower.googlepages.com.

The PowerPoint slides and audio of the talks will be posted after each session.

Syllabus

Global warming continues. The world consumes oil and gas faster than finding it. We import oil from unstable countries. Producing ethanol from corn consumes almost as much energy as the ethanol delivers. Sites for wind and hydro power are limited. Can more nuclear power help? Are the health risks acceptable? One theme will be how many? How many acres of corn? How many power plants? How many windmills? How many tons of uranium? How many tons of CO2?

1. Introduction

Energy units, uses, sources
Social benefits, demand growth, conservation, developing world
Periodic table, nuclear fission, nuclear power plants

2. Fear

Chernobyl, Three Mile Island
Radiation, health, safety, waste
Nuclear weapons proliferation

3. Environmental choices

Oil and gas depletion
Global warming, mining, coal, oil shale, tar sands
Wind, hydro, solar
Corn, sugarcane, cellulosic ethanol, biodiesel
Uranium and thorium availability

4. Current technology

Submarines and ships
Operating nuclear power plants, industry structure, NRC
Current products: GE, Westinghouse, Toshiba, Areva

5. Nuclear power plant visit

Vernon

6. New technologies

High temperature gas reactors, liquid metal reactors
Hydrogen production, hydrocarbon synthesis, coal-to-liquid, electric cars

7. Global Nuclear Energy Partnership

Integral fast reactor, waste reprocessing
Fuel supply for non-nuclear nations
Current public awareness, funding, activities

8. Debate

Antinuclear activism, Union of Concerned Scientists, Caldecott
Public opinion, NEI, environmentalist shifts
Congressional and presidential candidate's views

Compare Coal Power to PBR Nuclear Power

Trainloads of coal power the US electric grid

A typical 1,000 megawatt coal fired electric plant burns a mile-long train of coal every day. Burning these 11,000 tons of carbon fuel creates 3.6 times as much carbon dioxide, because each C12 binds to two O16 atoms. If we were to capture all that carbon dioxide, refrigerate and liquefy it, it would fill a train of refrigerated tank cars over 3 1/2 miles long! Remember, this is for one day, for one power plant of at least 400 in the US. Clean coal advocates propose to sequester these liquids.


US Carbon Dioxide Source (US EPA)

Coal contributes the energy for half the electricity generated in the United States. It is relatively inexpensive and readily available, with centuries of supply available. However, coal is the largest source of carbon dioxide emissions into the atmosphere.


Proposed new US Coal Burning Electric Power Plants

A 2007 EPA study reveals that the electric power industry plans to build 159 new coal electric generation plants in the next years, to generate 96,000 megawatts of power at a construction cost of $141 billion. China is building one new coal fired power plant every week. China and the US seem to be vying to be the world's top CO2 emitter, with China projected to pass the US in the pollution race in 2009.

Coal is more than a source of electric power. Coal gasification can produce liquid transportation fuels, as SASOL is already doing in South Africa. China is to build 8 liquefaction plants by 2020, with output sufficient to displace 10% of China's oil imports. The process captures about half the energy from the coal. The rest is lost as heat with the release of carbon dioxide. In all, burning transportation fuel produced from coal releases twice the CO2 that using petroleum sourced fuels does.

Clean coal comes from sequestering carbon dioxide

The coal industry and environmentalists talk about carbon capture. The idea is to capture the carbon dioxide emitted from coal burning power plants and store it, sequestered from the environment. Two commonly proposed places to sequester the CO2 are under ground or under the sea. To pump more oil from depleted oil fields CO2 has successfully been pumped into the ground to force the oil out. But there are not nearly enough such places for all the CO2 the US currently emits. The place with enough room is the ocean. Liquefied CO2 could be pumped to the depths of the ocean, where it would remain liquid because of the immense water pressure miles below the surface. You can learn more at the EPA web site.

Sequestration is today only a promising future technology. No large scale sequestration is taking place. New technologies will be needed, because today's costs are too high -- $150 per ton of carbon. Compare this to the $40 per ton cost of the coal, and estimate the effect on electric power costs.

The United States Department of Energy did establish seven regional partnerships to explore sequestration. In October, 2007, DOE awarded $318 million for three demonstration projects to sequester CO2 underground.

Will the sequestered CO2 somehow leak back into the environment? In 1986 Lake Nyos in Cameroon was saturated with CO2 from volcanic sources. An unknown geological event overturned the supersaturated water at the bottom of the lake, bringing it to the surface where 1.6 million tons of CO2 effervesced into the atmosphere. The heavier-than-air gas suffocated over 1,000 people. Geologists say this will not happen with sea-sequestered CO2. The 1.6 million tons is about the amount of CO2 produced in about 40 days' operation of one large coal fired power plant.

Coal Integrated Gasification Combined Cycle can help

Combined cycle gas turbines have been successfully used in natural gas fired power plants. They generate power by burning fuel in a gas turbine engine, much like a jet aircraft engine. They also capture heat to make steam to generate additional power. Hence the name combined cycle. This technology is becoming applicable to the coal industry, too. The Integrated Gasification Combined Cycle (IGCC) plant may have an efficiency of 50-60%, compared to the typical 33% efficiency of today's coal plants. Sequestration advocates favor new IGCC plants because the carbon dioxide can be more economically captured. Of the 159 or so proposed new US coal plants, only 32 have been proposed. Only a handful are moving forward. None are in operation. The carbon capture technology has not been engineered and is not included in the plans. IGCC plants cost 10-15% more than pulverized coal plants.

But wouldn't IGCC plants be a good idea anyhow if they have 50% efficiency rather than 33%? We could make the same electricity with only 33/50 of the coal? They would reduce CO2 emissions by 33%.

Compare Coal Power to PBR Nuclear Power

Coal plants are the major source of carbon dioxide the US; nuclear plants do not emit CO2.

Clean, safe nuclear power exists; clean coal is a future technology. Carbon dioxide sequestration on the needed scale is an untested, emerging technology. Its safety needs proving. The expense would double the cost of electric power.

Per kilowatt hour produced, the death rate in the coal power industry is 40 times that of the nuclear power industry.

Coal has a role in industry. Coal or carbon dioxide from existing coal power plants can combine with hydrogen from high temperature gas pebble bed reactors to form vehicle fuels such as ethanol or methanol.

The website nuclearoil.com proposes a radical use for coal fired power plants -- replacing the boilers with nuclear reactors for heat.

Nuclear Oil is an antidote to the Peak Oil Blight

Oil production outside OPEC and former USSR

Peak Oil is a name given to a concept of resource depletion. The 2004 US DOE chart above illustrates that in Texas oil was first pumped from the earth in 1934. Texas oil production rose and then began falling as the oil was depleted more rapidly than discovered. Peak oil happened in 1971 in Texas. As oil runs out in one area of the world, further exploration and new technology has successfully found oil in others. The chart illustrates the peaking of oil production in other countries, excluding OPEC and the former USSR.

Marion King Hubbert developed the model of peak oil in 1956, and it has been controversial since then. The Association for the Study of Peak Oil developed the following chart, which represents worldwide oil production peaking in about 2010.



The Peak Oil Blight is the coming increase in CO2 emissions

Oil production will peak at some time in the not-too-distant future, and the world will run down the supply of easily pumpable oil. As the supplies lessen and demand continues the price of oil will increase, creating incentives for further exploration and the development of new technologies and sources. The sources include shale oil, tar sands, tar sludge, heavy crude, and coal. These alternative oil sources are plentiful. There are estimated to be one trillion barrels of oil in the Alberta tar sands. The Colorado Green River Basin has an equivalent amount of oil shale. Although the world might run out of pumpable oil in 50 years, there are over 500 years' worth of these alternative oil sources.

The technologies for converting these substances to oil and gasoline already exist; Germany made gasoline from coal in World War II. In the early 20th century, before natural gas pipelines, US cities made syngas (CO + H2) by spraying water on hot coke.

However, the conversion costs to make oil from the alternative sources are high both in terms of money and energy use. With current technology the energy will come from burning more such fossil fuel, increasing CO2 emissions. For example, diesel fuel can be made from coal. Creating and using coal derived diesel releases 45 pounds of CO2 per gallon of fuel, compared to 25 for diesel from crude oil. Shell Oil has a method for extracting oil from oil shale by heating the ground to 65o degrees F for 3-4 years to liquefy the oil.



Alberta tar sands excavation

Alberta tar sands are mined and then oil is extracted by heating in a retort. All these technologies require substantial heat, and that heat is provided by combustion of a large fraction of the products being extracted. Coal To Liquid (CTL) plants are already in operation. South Africa's SASOL produces 150,000 barrels per day.

Heat is used in the GTL (Gas To Liquid) plants under construction in Qatar and Nigeria. Such $18 billion plants will convert natural gas to ultra clean diesel oil, but 45% of the natural gas is consumed in the process.

Over the next 50 years, as pumpable oil is depleted, the price will rise, encouraging exploration of alternative sources and plants to extract the oil. These plants, burning more fuel, will emit more CO2. Unless society takes some actions, the invisible hand of economics may well drive the world to double CO2 emissions. This should be a nightmare scenario for environmentalists.

Nuclear Oil is an antidote to the Peak Oil Blight

Nuclear Oil is a name for oil produced using nuclear power. Pebble bed reactors and other nuclear reactors are good sources of heat. The high temperatures reactors can provide process heat to conversion plants that heat oil shale, oil sludge, or tar sands to extract oil. The overall productivity of the conversion plants would be increased and CO2 emissions eliminated by not burning the end product for heat.

Nuclear reactors can be built at the production sites, such as the Alberta tar sands pits, the Colorado shale oil lands, the West Virginia coal mines, the Qatar gas fields, or the eastern Venezuela sludge oil fields. The oil extraction and production processes can take place more efficiently, using nuclear heat, without creating even more CO2.

The website nuclearoil.com has much more about peak oil and the opportunities to use nuclear power to reduce CO2 contributions and extend the availablility of fossil fuels. It is comprehensive, written in a sassy style, and filled with links to explore the subject.

Summary

Vehicle fuels like gasoline and diesel will be used for decades. Oil depletion and natural economic forces will encourage extraction of oil from alternative sources, releasing ever more CO2. Nuclear heat can eliminate the need to burn fuel and release CO2 during production.

PBRs can halve global warming CO2

In February, 2007, the Intergovernmental Panel on Climate Change published the report Climate Change 2007 which gave further evidence that (a) the climate is warming, and (b) human activities are part of the cause. Most of the press coverage focuses on the warming, the shrinking glaciers, starving polar bears, and rising oceans. The evidence that man-made greenhouse gasses actually cause the global warming is harder to communicate. The report quantitatively models the contributions of various human-caused components, such as CO2, N2O, and CH4, of which CO2 is the largest.

To my mind, the clearest evidence is the above chart, published by NASA. Over the last 170,000 years atmospheric CO2 levels and global average temperatures have changed in tandem. The two graphs are too similar to be attributed to chance. The frightening aspect, at the top right, is the sudden increase in CO2 levels of the last decades. This portends a similar increase in temperatures. Pebble bed reactors can decrease future CO2 emissions. Here's how.


Quads of fossil fuels burned annually in the US


One quad is one quadrillion [10^15] BTU per year. The first post in this blog has a DOE energy flow chart indicating consumption of 55 quads of US fossil fuel plus 29 quads of imported petroleum. These 84 quads are burned, producing CO2. US coal, primarily for electric power, accounts for 23 quads of this. We can begin to cut CO2 emissions by replacing coal electric power with nuclear electric power.

The previous post showed how pebble bed reactors can be built in factories, much as Boeing builds airliners. Boeing builds at least one airliner per day. Let's suppose we build just one PBR module each week to replace coal-burning electric power. The thermal efficiency of a coal power plant is about 33%, so it takes 3 times as much energy in as it sends out. Here's how many quads of fossil fuel one 100 megawatt PBR module can save.

100 x 10^6 watt [1 megawatt = 106 watts]
x 3.4 BTU / watt hour
x 24 hours / day
x 365 days / year
x 3 [to account for 33% efficiency]
x 1 quad / 10^15 BTU / year
= 0.0089 quad

So building one PBR module per week displaces 0.0089 x 52 = 0.46 quads of fossil fuel energy every year thereafter. The bar chart above illustrates the concept. The displaced quads can be from coal, crude oil, or natural gas.

Deploying pebble bed reactors can reduce the US-produced CO2 that contributes to global warming, by half, in this century.