Posted by Max Dunn Tue, 31 Aug 2010 21:41:50 GMT | no comments
Have you ever wondered where energy comes from and where it goes? Well, wonder no more – here is a great energy flow diagram from Lawrence Livermore Labs that presents this information in a straightforward way:
Comparing the tiny, thin lines from solar, geothermal and wind against the big, fat lines from fossil fuels shows us that we have a long ways to go to a sustainable energy infrastructure!
Posted by Max Dunn Tue, 31 Aug 2010 17:04:32 GMT | no comments
Prices of solar photovoltaic (PV) systems have come down drastically in the last few years. Many solar modules can now be purchased for less than $2 per watt. There has been some speculation that these low prices are due to a glut of solar capacity that is causing manufacturers to sell below their cost. However, a tidbit in a Pike Research blog entry revealed this:
First Solar’s 11.2% efficient modules cost $0.76/W to make according to company reports, and total manufacturing cost of c-Si modules produced by the most competitive companies has plunged to about $1.20.
So in actuality, the solar manufacturers can still make a healthy profit by selling their modules at $2 per watt. Let’s hope that prices comes down even further!
Posted by Max Dunn Wed, 07 Jul 2010 03:36:35 GMT | no comments
I have long heard that oil companies get a lot of special tax breaks, but no-one has ever been able to explain clearly what those tax breaks actually are. Now an article in the New York Times As Oil Industry Fights a Tax, It Reaps Subsidies provides the best explanation I have seen. Some of these tax breaks are:
While some of these ploys are also employed by other industries, like moving their headquarters outside the US, the US tax code makes it especially easy and profitable for oil companies to employ these tactics.
Furthermore, many of these tax breaks no longer have any valid reason for existence since they were enacted a century ago to encourage oil exploration in the fledgling industry and then later in the 50s to decrease Soviet influence in the Middle East.
It is estimated that these tax breaks averaged $12 billion from 2006 to 2008. While this is a large number, it is only a small fraction of the $280 billion the oil industry was taxed in this period.
Nonetheless, with a growing deficit, dismantling these archaic tax breaks for the oil industry would raise badly needed revenue and help reduce the unfair advantage that the oil industry holds over cleaner forms of sustainable energy.
Posted by Max Dunn Fri, 06 Nov 2009 02:12:50 GMT | 2 comments
What is better – to save water or to save electricity? This is a tradeoff that businesses and industry concerned about sustainability often need to make, and it is not an easy one.
However, an article in the November 6th, 2009 edition of The Economist called Current thinking: Cheaper desalination provides this tidbit: “Even the best reverse-osmosis plants require 3.7 kWh of energy to produce 1,000 litres of drinking water.”
Converting to gallons, this means that 70 gallons of water can be produced from salt water with 1 kWh of electricity. So there we have it – a way to compare water savings to electricity savings.
Posted by Max Dunn Fri, 18 Sep 2009 02:27:41 GMT | no comments
Here is a study that looked at Energy Return on Invested (EROI) of windmills and found they returned over 20 times the energy use to make them, which is favorable with fossil fuels, nuclear and solar power.
Meta-analysis of net energy return for wind power systems
Posted by Max Dunn Thu, 10 Sep 2009 21:34:37 GMT | 1 comment
Some people claim that more energy goes into making a solar photovoltaic (PV) panel than it will ever produce. While years ago that may have been the case, it certainly isn’t true any longer.
The US Department of Energy looked at several studies and concluded that multi-crystalline PV has an energy payback of less than 4 years and this will likely go down to below 2 years soon. Thin-film technologies have an even shorter payback period. With an estimated 30-year life, solar PV is actually a very good energy investment!
Posted by Max Dunn Tue, 28 Jul 2009 14:32:11 GMT | no comments
When looking at the economics of building solar panels, one important factor is how much the factory costs.
By comparison, the fuel for a nuclear power plant is very inexpensive and the main reason why nuclear power is so expensive is that the nuclear plants cost so much to build. Is this also true for solar panels? Do solar panel factories costs so much that even if the marginal cost of producing a solar panel comes down, will the cost of the factory still keep the prices high?
If the recent announcement of a thin-film solar panel factory is any indication, then solar panel plant costs are very low.
This factory will cost about $150 million dollars and produce 100 MW of solar panels per year. Over 10 years, this will add only $0.15 per watt to the cost of the panel. Considering that we only need to get solar power down to about $2.00 per watt to be competitive to coal, the cost of the factory is not a problem.
So it appears that the cost of solar panel factories will not be the limiting factor in bringing down the cost of solar power.
Posted by Max Dunn Sat, 25 Jul 2009 15:08:16 GMT | no comments
A friend of mine recently got a 400cc Suzuki Burgman scooter and loves it. He gets 53 MPG which is pretty good, but realized that it was about the same as a Prius that gets 48 MPG. “Why is this?”, he asked. The Prius weighs about 3000 lbs while the scooter is only 400 lbs.
Let’s look into this.
Regenerative Breaking
Even though the scooter is a lot lighter, the Prius captures about 50% of the energy when breaking and uses it to accelerate. So this brings the effective weight of the Prius down to 1500 lbs.
Wind Resistance
Even though the scooter has a frontal area 4 times smaller than a Prius, a scooter is not very smooth going through the air. It has a coefficient of drag (Cd) of about 0.9 versus about 0.26 for the Prius. Adding this up, the total drag coefficient (Cd x A) for the Prius is 6.24 and the scooter is 5.4. This means that the scooter takes almost as much energy to overcome wind resistance as the Prius!
Motor Efficiency
Small engines are not very efficient, while Prius engines are very efficient.
Conclusion
Add them up: the extra weight is not as significant because of regenerative breaking, the wind resistance is about the same and the motor is much less efficient. Given all this, it is not surprising that the scooter and the Prius get about the same gas mileage!
Posted by Max Dunn Tue, 12 May 2009 16:13:05 GMT | no comments
- Michael Reilly, Discovery News, May 11, 2009 – Forget peak oil, a series of new estimates of the world’s coal supply suggests reserves may be vastly overestimated, and if the planet isn’t running on a majority of alternative energies within the next few decades, we could be facing an unprecedented global energy crisis.
On the flip side, a dwindling supply of coal could also throw the breaks on global warming, some argue.
Common knowledge about coal is that major producing nations like China, the United States and Australia, have enough to last hundreds of years, far beyond the reach of oil, which may already be in its twilight years. But worldwide coal production could plateau as early as 2025, according to one new estimate, and a growing group of scientists are concerned that fossil fuel supplies may begin dwindling by mid-century.
Last year, David Rutledge of the California Institute of Technology analyzed the coal production patterns of five regions around the world – eastern Pennsylvania, France, Germany’s Ruhr Valley, the United Kingdom and Japan – each of which was producing at less than a tenth of its peak levels.
He found that each of the depleted regions followed a rough bell curve of production; initial production was followed by a steep ramp-up, a plateau near peak levels, and then a consistent decline.
When he applied the same formula to coal data from around the world, the results were startling: the United Nations Intergovernmental Panel on Climate Change’s maximum estimate for extractable coal is about 3,400 billion tons. Rutledge’s calculations suggest just 666 billion tons.
Posted by Max Dunn Tue, 28 Apr 2009 21:47:25 GMT | no comments
Many organization are looking for ways to reduce their garbage and increase composting of the disposable cups. However, it turns out that the styrofoam (also known as extruded polystyrene foam or XPS) versus paper question is more difficult than it first appears.
One big problem is that the coating on the paper cups which keeps it from leaking also makes it difficult to recycle or compost. And the cups themselves contain very little recycled paper.
An old study from Science shows that on almost every count, except cooling water and biodegradability, the styrofoam cups are more eco-friendly.
A newer study also concludes that to process the raw materials about six times as much steam, 13 times as much electric power, and twice as much cooling water are consumed to produce the paper cup as compared to the styrofoam cup.
The same study found that landfill disposal of the two items under dry conditions will occupy similar landfill volumes after compaction and neither will decompose much. Under wet conditions, styrofoam will not readily degrade but may help other materials to do so, while the paper will decompose giving off methane, a significant greenhouse gas.
Another possibility is to recycle the styrofoam cups, although this is hard to find. There are mail in recycling centers in Redwood City and Hayward that take them and Imagine Surfboards makes surfboards out of used styrofoam cups.
It is too bad that there isn’t an easy solution to making disposable cups more eco-friendly.