Archive for May, 2009

Definitions and other matters

Once again, while wandering on another social media site, I ran across a question that needed answering. This time, someone wanted to know why hydrogen was never mentioned as a renewable energy source. As I wrote a response to this individual, I realized that there is significant potential for confusion and incorrect thinking around all of these terms that are thrown around today for various energy sources.

Baseload Power – Power that is generated pretty much continuously. Electrical use goes through peaks and valleys over time periods, baseload is that minimum power level that is pretty much always demanded. Most utilities will define different baseload levels for summer and winter. This seems to be a concept our FERC chairman, Mr. Wellinghoff, does not grasp. Baseload power is usually generated by the least expensive source available to the utility, but supply must be highly reliable. The three sources most commonly used for baseload power today are coal, nuclear, and hydro. Some regions use oil.

Low Carbon (Carbon free) Energy – Those sources of energy that emit little or no carbon dioxide (CO2) in the generation of energy. There is significant disagreement over how to tally the carbon impact of each energy source. Usually, it depends on the agenda of the author of any given study. Most agree that all hydrocarbon sources are NOT low carbon energy sources. All others can be considered low/no carbon sources. This includes geo-thermal, hydro, nuclear, solar, and wind. There are several more under development that may be added to this list.

Reliable Energy – Energy sources that can be relied on for consistent power generation over long periods of time. These sources are frequently considered for baseload supply. This term is not used as frequently because in the developed world, energy reliability is inherently assumed. However, as we consider new energy sources, reliability becomes important. For this article, I will assume reliable energy must be available > 75% of the time. Reliable energy sources today are coal, nuclear, hydro, oil, natural gas, wood.

Renewable Energy – These are those sources of energy that are either easily regrown, or are constantly available. Renewable forms of energy include, ethanol, solar, wind, hydro, geo-thermal, wood pellets. Renewable energy is perhaps the most misunderstood phrase in the energy pantheon. Many people believe that renewable implies ecologically sound, sustainable energy. This is not the case. Ethanol and wood pellets both are sources of atmospheric carbon, both are also not sustainable in the long term. Ethanol is currently made using corn. This places food and energy production in direct competition for land and resources.

Sustainable Energy – Those sources of energy that can be used long term with minimal total impact on the environment and without depleting the fuel source. Most consider this the intersection of renewable and low carbon sources. Typically, solar, wind, and geo-thermal are considered sustainable energy sources. Arguments for nuclear, hydrogen, and hydro are also quite compelling.

I hope that by spending a few minutes reading these definitions, I have provided some clarity to these discussions.

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May 8, 2009 at 1:09 pm

Solar Panels – the math

On another social media network, the question was posed…”If every single rooftop in the country was covered in PVs, I’ve heard that we would generate enough electrical energy not to need any other source of electrical power! But, has anyone done the maths?”

The questioner was from the UK. Many people immediately jumped on the issue as a dumb idea because of many other logistical issues, but no one “did the math”. Anyone that knows me at all knows that I tend to “do the math” first then look at the resulting implications.

Basis and Assumptions:

On average the sun provides about 1000 watts per square meter (at sea level, higher as you go up in elevation, but a convenient number for my purpose…)

Current solar panels are currently less than 30% efficient. We’ll use 30% because it makes the math easier. We’ll add “windage” later.

Let’s be generous – given Britain’s famous weather – and say you can generate electricity from all panels at this peak efficiency for 10 hours per day, 365 days a year.

Current consumption in UK is nearly 400TwH per year.

The Math

Solar panels (at 30% efficiency) generate 300 watts per square meter. So for each hour of sunlight, they generate 300 watt-hours or 0.3 KwH.

Over a 10 hour period, each square meter of solar panel can generate 3 KwH of electricity. Over the course of a year, each square meter could produce just over 1 MwH of electricity.

To generate 400 TwH of electricity would require almost 400 square kilometers of solarpanels.

If, on the average, one could put 2 square meters of PV’s in the most optimal south facing position on the roof of a building, then you would need 200,000,000 buildings.

Given my rather positive assertions related to both efficiency, and available sunlight, I would double that for a realistic scenario. SO, you would need to put PV’s on 400,000,000 buildings

Conclusions

Solar panels are not a panacea that will solve all of our problems. My scenario above ignores the complex grid and energy storage structures that would be required to move electricity from such a dispersed generation to concentrated population centers and industrial applications and storing summer generation for use in winter. I’m sure any utility engineer could add dozens more considerations that I’ve not mentioned.

I believe that all of the low carbon emission options must be explored and applied to the maximum extent feasible to lower both dependence on non-domestic sources of fuel and GHG impact on our planet. But, we must maintain a balanced application of all of these technologies in order to maintain a society we all want to live in.

May 6, 2009 at 1:00 pm 3 comments

A Parable of Power

A farmer in western Venezuela is tired of his intermittent electric power. For several hours every day he is without electricity. Why? Primarily because Venezuela’s government controlled electrical system is inadequate to the growing population. They have large hydro electric dams in the eastern part of the country, closer to Caracas, to the major population center of the country. But that power must travel across the country on an unreliable grid to get to the farmer’s property in the mountains above San Cristobal in the west. So, for several hours each day, the farmer is without power.

This is more than just annoying for the farmer. Because he has no centralized source for water, he relies on a local well for his water with a pump. When there’s no electricity, there’s no water either. If there’s not water, he can’t water the tender plants in his subsistence garden when the rains don’t come at the right time. He also can’t get water for bathing and cooking.

So what should this farmer do?

Well, first, he built some additional tanks to store water so that during these outages, he can water his plants, cook his food, and keep himself and his family clean. But still, this lack of power holds the farmer back. Unreliable power is a key contributor to his community’s inability to grow and develop. They cannot count on electricity to light their homes, heat their water, run their computers.

So what should this farmer do?

He decided to put in something to generate electricity whenever the government provided system failed. What should he install?

A solar array? He lives in an equatorial region high in the mountains, a solar array would certainly provide significant power, but only during daylight hours and not at peak efficiency when it rains (a frequent occurrence in this region). To install a solar array means that he must also install a complex battery storage system and inverters. He is not a technical person, this is more than he can manage.

A wind turbine? The wind blows down the valley to his home pretty steadily, but again, there is an inconsistency to deal with. Perhaps it would still suffice, at least most of the time, the wind blows sufficently.

A nuclear plant? Geo-thermal facility? Both require far more resources than the farmer has at his disposal, even his little community could not band together to build such complex facility. The Venezuelan government is giving serious consideration to a nuclear plant, but the time is years away.

So what DID the farmer do?

He installed a gas-powered generator. Why? Because the Venezuelan government subsidizes gasoline to where it costs about 5 cents/gallon. A generator is easily started when it is needed and can be run only when it is needed. It is a relatively simple mechanical system that the farmer and his community can maintain without a degree in engineering. At 5 cents/ gallon, fuel is relatively inexpensive compared to his income, so the operating costs as well as the initial installation costs are low.

So what is the lesson from this parable?

Ultimately, all of the “green options” failed for this farmer. Instead, he chose a technology that provided him with the needed power, in a way he could understand and manage. We, in the developed countries, sit in our heated and air-conditioned homes, with our computers, microwaves, and refrigerators and argue the relative merits of the low-carbon options that are available to us.

How do we change this conversation?

Added 5/5/09  This is not just a parable, but a true story, not something made up by me to provoke discussion. I personally know the farmer involved in making this decision. Some facts have been altered to preserve his anonymity.

May 4, 2009 at 11:22 am 4 comments


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