Saturday, November 24, 2007

Lots of Wasted Energy

If you spend any time looking at the national energy complex, one eye-catching part is the amount of energy that is lost to waste heat in the electric and transportation systems. In the following flowchart from the Lawrence Livermore National Laboratory, the energy flow in the USA energy system in 2002 is shown.

EIA has similar flowcharts similar to this on their website for all parts of the energy system. To see this flowchart effectively, you may have to open it up in a new window by right-clicking on it. While a little out of date, the numbers are still fairly close to what is used today in 2007 (we use over 100 Quads now), and the ratios are very close. In case you have forgotten, one Quad represents one quadrillion BTUs or British Thermal Units--a unit of energy that is so arcane that even the British no longer use it, but we Americans seem bound to it forever. For completeness, a BTU is the amount of heat required to raise the temperature of one pound of water from 60 degrees Fahrenheit to 61 degrees. Arcane, indeed, but we need not go there.

The numbers are staggering. In the electric system, close to 70% of the energy is lost to waste heat. In the transportation system, which dominated by petroleum, the loss is closer to 80%. The size of the numbers makes sense if you think about it. Most of the energy used by your car goes away in heat from the engine, and only about 20% is converted into making the car and its contents move. (Critics like Amory Lovins go even further and point out that most of that useful power is used to move the car and not the people in the car, and so the amount lost is 90-99%.) In the electric system, about 60-63% is lost to waste heat, and the bulk of the remainder (7-10%) is lost in transmission.

There are ways to capture most of this wasted energy. It is hard to use it to make more power, for you are fighting the 2nd Law of Thermodynamics (entropy). However, if what you want is the heat instead of the power, then you are in business.

If you look at how we use fossil fuels, a large fraction goes to heat: space heat, water heat, dryer heat, oven heat, etc. The way we traditionally do it, however, doesn't make a lot of sense (or, at least not any more). We burn coal at the power plant to make electricity, and the excess heat goes up the stack or into the cooling pond. We then take that power off the grid and start up the oven or the dryer. Further, we burn heating oil or natural gas in the furnace or boiler to heat the water or the house.

What if we were to take to power plant and put it in the basement? That is the idea of combined heat and power or cogen units. Instead of one big electric plant powering hundreds of sites, we distribute the generation out to the places where it is used. The excess heat is also used locally in other processes instead of being dispersed into the atmosphere, streams, lakes and oceans. We are about to do just that in our house. More details to follow as the cogen unit gets installed.

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Friday, November 16, 2007

So What Exactly What Are We Burning?

This post comes from a question on the geothermal analysis. We are burning less heating oil now, but we are using more electricity. What, then is used to generate the electricity that runs the heat pumps? The answer to that question depends upon where you live and what the marginal fuel is in that area. Here I look at Connecticut, because that is where I live.

The data used in the post can be found at the ISO-New England website.( In particular, I used the hourly demand data and the capacity data from the 2007 CELT report. CELT stands for a Forecast Report on "Capacity Energy Loads and Transmission", and the report is published annually.

The figure below shows both the electric generation capacity in Connecticut and the demand. To see this plot and some of the details described, you may need to open the figure in a new window (right click and select "Open in New Window").

The capacity is stacked upon each other in a general manner of cheapest to most expensive. It is the nameplate Winter Capacity which is a little higher than the Summer Capacity. There are a few caveats to the generation capacity data. For instance, on any given day, the available capacity is usually less than the total capacity depending upon which units are down for maintenance or for other reasons. There is also the issue of fuel cost. The stacking assumes all of the natural gas plants can run cheaper than all of the petro-based plants. That isn't necessarily true and it depends upon the plant efficiency as well as the current fuel cost. Also, I've put the waste and bio-fuel plants just above the natural gas. It isn't clear if they should go above or below natural gas. What is not apparent, but is present in the plot, is a small sliver of wind and baseline hydro capacity operating below the nuclear block.

Superimposed on top of the generation stack is the historical hourly demand. The data show the minimum and peak demand over a 7-day window. This time period was chosen only to make the graph easier to see. I've also added the bulk of the hydro at the top of the demand data, because most hydro is peak-capacity power. Solar capacity is also included in the peak hydro part (you can't see it on this scale because solar power capacity is presently minuscule).

From the graph, one can see that the peak power demand is in summer, usually in early August in the late afternoon. When this happens, the marginal power is usually petroleum based. Minimum demand occurs in the early morning during the spring and fall--times when there is less heating, cooling, and lighting needs. Only during this period is there any encroachment into the coal capacity. Otherwise, coal is run pretty much continuously. The vast majority of the time, the marginal fuel is natural gas.

Yet another caveat is that CT is connected to other areas, namely all of New England, and the New England electric system has connections to New York and to Canada. The interconnections can mean that New England can bring in up to 2000 MW of power from other areas, the equivalent of CT's nuclear base. Not all of this is used by CT but is shared by all of New England, and some even passes through to New York, but when we are importing from Canada, we do get a larger hydro component than is shown here. That potentially reduces the coal use in spring/fall, but in the winter and summer, the marginal fuel is still natural gas.

The answer seems clear. For the winter heating, we are using more natural gas in place of the heating oil through the increased power use. In the summer, compared to a traditional air conditioning unit, we are using less petroleum yet again, due to the better efficiency (and cooler ground temperature) with the heat pumps.

Net-net, for heating efficiency purposes, we are more efficient, because on average, the natural gas plants, which are very efficient electricity producers, have efficiencies in the range of 30-50%, while the heat pump performance is about 3.5 to 1. In other words, for every unit of electric energy used, we get 3.5 times that in thermal heating. That amount is lost, however, as a result of the natural gas (or other fossil fuel plant) efficiency. There are also transmission losses from the plant to our house. Let's assume we have an efficient natural gas plant at 50%, our heat pumps have a coefficient of performance of 3.5, the transmission losses are 8%, and the efficiency of the boiler that is no longer running is 85%. Net-net, our gain is 3.5*0.5*.92/.85 = 1.9 (or 90% increase in efficiency). Even assuming a power plant running at 30% efficiency, the net gain is 1.14 (or 14% increase in efficiency). It isn't clear if these numbers will sink in (or even if they are correct!). Suffice it to say that the heat pumps mean we are now burning natural gas, and in addition, we are using the fossil fuels more efficiently. That is something I can live with, but can we do better? I think that we can...

Saturday, November 10, 2007

Coming Out

When I decided to start a blog, I chose to stay anonymous. There was no really good reason for this. Perhaps I was worried of blow back of some sort, but anyone who wanted to figure out who I was could probably piece together the information from the posts. Such an act would be diabolical, but nonetheless possible, I suppose.

Last week (Tuesday, November 6, 2007 to be exact), I was elected to local government. Because I was not well known in my hometown, Westport, CT, I gave people my blog address, so they could get a sense of my style and thought processes and to see what I've been up to with respect to moving towards energy sustainability. Some visited the blog, and I've heard some feedback, mainly that I need to update it more. That, I cannot argue with. At any rate, there is no reason to be anonymous any more, and hence the title of this post.

Since the start, we've worked on moving to a more sustainable energy use with modest success. The approach is different and less intense (although more capital intensive) than what you can find elsewhere on the web. Many people are a lot more hard-core than we are. An example of really hard-core is No Impact Man, a NYC resident trying to make no net impact on the environment. Another approach can be found at the blog of Sharon Astyk. Sharon is a New York state Jewish farmer working towards sustainability. Her primary motivations are peak oil and global warming, and her style is a bit more palatable than No Impact Man's, even though she's advocating, among other things, a 90% reduction in carbon emissions.

Locally, here in Westport, there are efforts going on. The Green Energy Task Force was initiated by Gordon Joseloff, our local First Selectman (basically, our Mayor), and under the leadership of Carl Leaman, they have estimated the town's carbon footprint and are working on recommendations on how to reduce that. The goal is nowhere near a 90% reduction, and if you are to believe the climate models, something near 90% will be needed. The Task Force's start is a reasonable one, and with time, I could easily see that it could get to advocating more drastic reductions.

As for me, I am still of the opinion that the most important problem is the geopolitics of oil: who has it, who doesn't, and the consequences of this relationship. We are working first to lessen our exposure to foreign energy sources in a way that is (hopefully) environmentally friendlier and that is more economical than what we have been doing traditionally. I've been working on this every since Hurricane Katrina, for that really opened up my eyes on the possibility and consequences of a major supply shock.

Listening to the news chatter, some seem convinced that the run-up in oil prices is a result of those pesky speculators. My response to that is that the speculators go to where the action is, and they wouldn't be in oil if there wasn't a supply/demand mismatch problem, and there is definitely a supply/demand mismatch problem, and it looks like it won't get better any time soon. We are talking years for it to work out at best, and if the peak oil people are right, it will never work out.

We've heard the refrain before, and so one has to ask what is different this time. The answer is that in the 1970s, we imported roughly 20% of our oil whereas now we generate 20% and import 80%. In addition, our position as a country has moved from being the world's largest creditor nation to the world's largest debtor nation. With our trade imbalance and our declining dollar, we may not have seen the last of the oil price rises. To stop that we will need to experience a global slowdown and not just one that is national. The increased demand from China and India is real and is the primary driver of increased oil use. Any reduction from US demand can be quickly replaced by increased consumption elsewhere.

At any rate, I'll be advocating locally for efforts to reduce our oil use first and foremost and doing it in a way that helps the environment, reduces our carbon footprint, and saves us money in the long run. That is the goal, but the energy complex is complicated. We'll see if we can get there. I'll also be commenting more on energy use in CT and in Westport and Fairfield County in particular. At least that is the goal I have. Can I get to 1 post a week? I'll certainly try.

Our personal efforts are not yet complete. Once you start on this project, you get quickly overwhelmed by the numbers involved, and we have a long, long way to go to get to where we feel comfortable with our personal vulnerability to energy risk.

Finally, a thank you to all those who voted for me. Town Representatives are elected at 4 per district, and there were 7 vying for 4 places in our District. The town turnout was 35.3% of the electorate and 37.8% in District 9. In District 9, 43.8% of the voters voted for me. It was enough to get me the 4th slot, but it only represents 16.6% of the electorate.

Kevin D. Green
Westport Town Representative-Elect
District 9