14 May 2010

Increasing Energy Production

In my last post in this energy series I determined that in order to alleviate world poverty we need to increase worldwide annual energy production from 474 exajoules (total production in 2008) to 734 exajoules (108 gigajoules per person per year). That's a difference of 260 exajoules.
This number is probably low because it assumes a 50% reduction in energy consumption in the U.S and Canada and it is based on today's population. The U.S. may not be able to achieve such efficiencies and worldwide population is certainly going to increase. For the sake of the following calculations I chose a target of producing an additional 350 exajoules.
The U.S. Energy Information Administration offers the following breakdown of worldwide energy production in 2006 (the latest year for which they've published data).
I've converted from BTUs to Joules. The total comes to 495 exajoules which is a little higher than the 474 cited in my previous post but the numbers are close enough to work with.
So, here are the prospects for generating an additional 350 exajoules from various sources:
Petroleum and Natural Gas
One gigajoule from oil costs $13.56.
One gigajoule from gas costs $4.74.
The Peak Oil theory dates back to 1956. It suggests that there will come a day where the remaining oil reserves are too expensive to extract and worldwide petroleum production will be forced to decline. Current projections are that peak oil will be reached on or before 2020. But the peak oil year has been moved back several times and there is good evidence that it's still a long way off.
Regardless of whether oil and gas reserves are nearing exhaustion, there are other problems with petroleum. Foremost is pollution. I'll defer debate about carbon dioxide as a pollutant to other authors. There still remain other pollutants including sulfur oxides, nitrous oxides, carbon monoxide and so forth. Natural gas burns more cleanly than crude oil products but it still generates pollutants. New automotive technology has reduced oil emissions to a fraction of their former levels. But these gains have been achieved in industrialized countries where regulations have encouraged such developments. In the developing world, emissions are much worse though the extent isn't accurately measured.
The other problem with petroleum and natural gas is opportunity cost. Presently we have no good alternative energy source for transportation. If we consume petroleum to generate electricity and heat, the cost of transportation will be driven up.
Due to the transportation link, petroleum use will be around for a long time. But, it's hard to consider massive increases in oil and gas consumption as a sustainable solution for meeting poverty's energy needs.
One gigajoule from coal costs $3.24.
Among fossil fuels, coal is the low-price leader. For this reason, coal supplies 49% of electricity in the United States, 69% in China and 40% worldwide. In the United States it is estimated that enough coal is recoverable to last 146 years at current growth rates.
So, there is enough coal to last for quite a while and it is inexpensive. But as with Oil and Gas, pollution is a problem. For those concerned about carbon dioxide emissions, coal releases about 35% more CO2 than gas or oil for the same amount of energy. More concerning to me are emissions of soot and sulfur dioxides. In the United States, scrubbers, are used to keep emissions relatively clean. However, most Chinese plants lack such scrubbers and China burns more coal than the United States, the European Union and Japan combined.
One gigajoule from hydropower costs $2.36.
Hydroelectric power is a nearly perfect solution. It's renewable, non-polluting, extremely efficient and it can be stored (in the form of reservoirs) until needed. However, though they don't pollute, dams and reservoirs have considerable environmental impact. In the United States, we've already harnessed just about all the hydropower available. More might be available in the developing world but not enough to deliver the needed 350 exajoules.
One gigajoule from a wind farm costs $13.89.
With new technology, the cost of wind power has dropped by more than 80% in the last two decades. Despite that improvement, it's the second most expensive source of energy on this list. The amount of wind energy that can be generated per acre varies tremendously with the amount and consistency of wind in that area. A representative example is the mega windfarm proposed by T. Boone Pickens which would produce 4,000 megawatts from 200,000 acres. That works out to approximately 630 gigajoules per acre per year (assuming that the 4,000 megawatts is average production). Unfortunately I suspect that 4,000 megawatts is peak production during ideal wind conditions. Giving the benefit of the doubt and assuming 4,000 megawatts is average, this kind of wind energy density can supply the total energy needs of six people per acre.
To be clear, I'm using the total energy need per person, not just electricity. It includes lighting, heat, cooling, transportation and the energy required to manufacture and produce all goods used by that individual.
While wind will make important contributions to overall energy production, the cost of production and low energy density per acre prevent it from being more than a small contributor to the overall solution.
One gigajoule from solar-voltaic panels costs $83.33.
Direct Insolation is the amount of solar energy delivered per square meter per day. In my city of Provo, Utah it averages 4.64 kWh/m^2*day. That works out to 6.1 gigajoules per square meter per year. The best solar cells ever tested achieve 41.6% efficiency in the laboratory. However, using solar cells of practical cost without tracking or concentration systems, the best efficiency to be expected is about 5%. Assuming these parameters, it would take 354 square meters of solar panels to supply the energy needs of one person. The roof of a typical suburban home is about 150 square meters.
This shows that the energy density of solar power starts to approach practicality. Presently, the big barrier is the cost of manufacture. At Today's Prices, a 354 square meter solar array would cost approximately $1.4 Million. This explains why solar power is far and away the most expensive source.
Solar-voltaic technology is advancing rapidly. The cost of manufacture is dropping and the efficiency is climbing. There are other solar technologies such as passive solar heating, solar water heating and solar concentrators which may cost less than solar-voltaic systems. There are also problems. Solar power is not consistent which means energy storage or alternative sources are needed for night and cloudy days.
Solar power--particularly solar-voltaic panels--is ideally suited to urban rooftops. Not only do panels deliver peak power during peak electrical demand (for air conditioning) but by converting light into electricity they reduce heat uptake on the roof thereby reducing the air conditioning load in the summer. However, for this to be practical, cost of manufacture would have to be reduced to about 5% of current costs. That's a tall order.
One gigajoule from nuclear power costs $1.42.
Nuclear power is the least expensive energy source available. The amount of energy that can be produced is tremendous, there is enough fuel to last millennia and the environmental impact is the least of all the energy sources cited.
The problem with nuclear power is that while the actual environmental impact is very small the perceived environmental impact is large and, in an accident like Chernobyl, the potential impact is tremendous. Clearly the perception of environmental impact is due to the potential for disaster. This has resulted in a political atmosphere that has severely limited the construction of new power plants since the Three Mile Island incident.
Another problem with nuclear power is the prospect of repurposing a power plant or its waste products into nuclear weapons.
New technologies for nuclear power are emerging that address the potential for disaster as well as limiting the prospects for repurposing. Those will be the subject of my next post on energy.
Energy prices were obtained from the following sites. Each was converted into dollars per gigajoule As prices fluctuate with the market the numbers you see as you follow the links may not be the same ones I used. Likewise, prices or some sources like coal can vary by as much as 60% depending on region. In each case, I selected prices that seemed to represent the majority of the market.
Energy Content of Fuels
Spot Price of Oil
Spot Price of Natural Gas
Spot Price of Coal
Hydroelectric Energy Cost
Wind Energy Cost
Solar Energy Cost
Nuclear Energy Cost (In Europe)

Other posts in this series:
Scotty, We Need More Power!
Energy: The Future is Nuclear

12 May 2010

Quote of the Day: Anna Stone

"Improvisation, if you don't have something worthwhile to say, is just hot air."
(Anna Stone, English Teacher Extraordinaire speaking on the importance of knowing the subject and the historic context before relying on oratory skills.)