Wednesday, February 16, 2011

Clean Energy Part 2: Swallows and Coconuts

There’s a memorable part in the 1970s movie Monty Python & the Holy Grail where King Arthur argues with a guard on a castle wall about whether a swallow could have carried a coconut to England, the punch line being is that an African or European swallow?

Fact checking about birds aside, the point of the story is if you don’t have the ability to lift a coconut you need to increase capacity by adding more swallows, or find yourself an African swallow.
Needless to say, when it comes to generating electricity, we are dealing with a very big coconut. In 2010, the U.S. Energy Information Administration (EIA) estimates that the U.S. consumed about 4 trillion kilowatt-hours of electricity. By 2035, the year that we are to reach the goal of 80% of our electricity from clean sources, that number will be about 5 trillion kilowatt-hours. In average electrical generation, we can divide those figures by the total hours in the year and see that, on average, we use about 474 gigawatts (GW) now; and that number will grow to about 587 GW by 2035.
We can similarly look at the major sources of electricity through EIA’s tables and compare average generation with the capacity of the five major sources of electricity. As with the coconut story, capacity must be greater than the average generation, or else our coconut will be staying on the ground. But, not only must the capacity be greater, we also need to have a surplus of capacity because the 474 GW is average generation; additional capacity is needed somewhere in the grid to handle those times of day and year when the demand is greater, that is, when our variable weight coconut is heaviest.


Data from EIA 2011 Forecast Tables


The chart for 2010, above, shows % capacity, which is average generation divided by the capacity of each source. Some refer to this as the capacity factor; others as overall efficiency because it takes into account all the factors that can affect power generation.  These factors include: mechanical availability (the amount of time a plant can run between breakdowns and maintenance); Mother Nature (the efficiency of thermal plants on hot or cold days, the ability of a hydroelectric plant to run during high water or drought, or the number of windy days in a year that can sustain a wind farm); flexibility of a plant to start or stop (also called dispatchability); and the cost of the energy sources. Taken as a whole, these factors influence whether a plant runs all the time and supplies base load to the grid, or during those periods of high demand (heavy coconut) when additional "peaking power" is needed.


In the 2010 chart, we see the highest capacity factors are highest for nuclear and coal, the two primarily sources for base loads, and are much lower for hydroelectric and natural gas, which have the flexibility to serves as the primary providers of peaking power.  The low capacity factor for wind, at 28%, reflects mostly the limits of Mother Nature, and does not fall easily into either role of base load or peak generator.



Changes by 2035 

Looking out to 2035, we can see EIA is forecasting no surprising changes in average generation or capacity.

Data from EIA 2011 Forecast Tables

      

Coal and natural gas are expected to pick up most of the increase in average generation, accounting for 395 GW of the 587 GW required by 2035. Natural gas does so with an increase in capacity that indicates additional new plants will be built, but the capacity factor of 27% indicates natural gas will continue as our primary source of peaking power.  Coal shows no net gain in capacity and an increase in its capacity factor to 78%, a combination which indicates coal plants will be better utilized in base loads and, if additional plants are built, their capacities will be offset by those being retired.
Nuclear, hydroelectric, and wind show relatively minor changes in generation and capacity.  The net gain of 10 GW in capacity for nuclear is the equivalent of several new nuclear power plants.  Considering the enthusiasm for new dams, one is left wondering where 3 GW in new hydroelectric capacity can come from. Fans of wind power will recognize that a 19 GW increase in capacity is not a very ambitious goal considering that 20 GW of new wind capacity has been built in the U.S. since 2007 alone. It may be that there is some skepticism regarding the potential to incorporate a large increase in the contribution of wind power to the grid.  
Adding together the average generation from the five energy sources gets us to 549 GW of the 587 GW needed by 2035. In EIA’s forecasts, the other 38 GW are found in a variety of other sources, including biomass, solar, and geothermal.  Whether these other sources are up to the task, or the balance will be taken up by the major five, remains to be seen.


Changes to Achieve Clean Energy

This brings us to the larger question of how to achieve President Obama's recently stated goal of obtaining 80% of our electricity from "clean" sources by 2035. In his State of the Union speech, the President spelled out part of the answer when he said that clean sources are: wind and solar, clean coal, natural gas and nuclear. The one item not on the list is plain old coal, as opposed to clean coal. As discussed in my previous post, one approach to the 80% goal is clean coal technologies. But how much new clean electricity do we need?  
Taking 80% of 587 GW gives a 2035 target of 470 GW of generation in the clean category. If coal is omitted for the moment, we are left with natural gas, nuclear, hydroelectric, wind and the 38 GW in the Others category, above.  All of these are on the clean list and total 337 GW of generation. Subtracting the 337 GW "already clean" from the 470 GW target leaves 133 GW required for new clean electricity. 
So, there it is: if you are a power producer, there are 133 clean gigawatts for the taking. Hydroelectric is most unlikely (or say conventional hydroelectric, leaving the option open for tidal power). Nuclear has the potential for additional capacity through more power plants or expansions to existing plants, but faces an uphill battle in permitting.  Wind has scope for additional capacity, but, if we look at the capacity factors, the number of new windmills becomes daunting. Among the big five, that leaves us with coal and natural gas. If clean coal, by which we mean dealing with the carbon dioxide, is not possible, that leaves natural gas. As advocates of natural gas point out, the carbon dioxide emissions are up to 70% less than from coal (which is the reason natural gas is on the clean list) and we have abundant resources, so the potential is there for natural gas to make inroads against coal. Doing so, however, requires significantly expanding the role of natural gas from peaking power into base loads. Perhaps there is an African swallow on the horizon, but for now, it looks like we are left with coal and natural gas to do the heavy lifting.


Links:
1. That bit about swallows:
http://www.youtube.com/watch?v=rzcLQRXW6B0
2. EIA 2011 Forecast tables:
3. Wind Capacity:

Tuesday, February 1, 2011

Clean Energy: Between the Lines

In last Tuesday’s State of the Union address, President Obama announced: “by 2035, 80% of America’s electricity will come from clean energy sources”.  The first question that comes to mind is: what are we counting as clean energy?  The second question: what do we have to do to get there?

First Question: What Is Clean Energy?

The President went on to give us an indication, saying: “Some folks want wind and solar. Others want nuclear, clean coal, and natural gas. To meet this goal, we will need them all.”


“Some folks” may have been a bit surprised and perhaps disappointed to see nuclear, clean coal and natural gas included that statement. Do an internet search for clean energy, and you’ll come up definitions that include the words sustainable, renewable, green, environmentally-friendly, and non-polluting. Usually included are references to wind, solar, biomass or biofuels, hydropower, and geothermal. Usually not included are nuclear and hydrocarbons, which, by nature, are extraction intensive, depleting, and generate waste in one form or another. Some definitions do include natural gas, however.

Proponents of nuclear, coal and natural gas were no doubt pleased by the President’s statement. Correction, clean coal, that is. 

One might question whether the statement was really sincere, or whether the separation into two sentences with the words “Some” and “Others” was some sort of code: “Some” sources of energy we like, “Others” we don’t. 

Nuclear, after all, has the decades-old waste disposal problem. The problem didn’t get any better last year when the government pulled the plug on the Yucca Mountain disposal site in Nevada.

The natural gas industry was no doubt happy to be mentioned, and usually gets props for being the cleanest of the hydrocarbons in terms of carbon dioxide. There is that little practice of hydrofracking, however, on some people’s minds. 

Then there’s coal, I mean clean coal: provider of over 40% of our electricity now, but the worst of the hydrocarbons in terms of carbon dioxide, and that’s without mentioning its other problems that from time to time crop up in the news (explosions, fly ash, dam failures, and mountaintop mines).  Clearly, when it comes to the idea of whether coal can be "clean", there are those who don’t believe it and those who believe there will be a technological solution to the problem of carbon dioxide. The country has vast reserves, and the key word to remember here is jobs. 

The Unmentioned

We are talking about clean energy for electricity, not transportation, but it's worth mentioning the persona non grata of the evening: oil. This was made clear with the President saying:
“... I’m asking Congress to eliminate the billions in taxpayer dollars we currently give to oil companies. I don’t know if you’ve noticed, but they’re doing just fine on their own.”

Also left out of the clean energy statement was biofuels, but, again, we’re talking electricity, not transportation.  Biofuels had their own special recognition in the President’s statement: “With more research and incentives, we can break our dependence on oil with biofuels, and become the first country to have a million electric vehicles on the road by 2015.”  

Others in the unmentioned category: hydropower, geothermal, and fuel cells. Hydropower is already a significant contributor to renewable energy in EIA electricity statistics. Don’t expect any growth in this sector, unless you’re thinking of tidal power: hydropower is a still just a nice way to avoid saying the word dam. Geothermal is looking like the Rodney Dangerfield of renewables; if it's not third behind wind and solar, it's left out entirely. Its omission on Tuesday appeared intentional.  Fuel cells were mentioned in another line about innovation, but, we've been hearing about them for years.  Hybrids and EVs are winning in transportation, and so are wind and solar in serious power generation. Like geothermal, fuel cells went unmentioned for a reason.
                

Second Question: How do we get there?

Clearly, if we take quick look at our current electrical energy balance, we see it makes a big difference whether nuclear, coal and natural gas are included in the clean energy mix.  EIA statistics show our current sources of electricity are currently 45% from coal, 23% from natural gas, and 20% from nuclear, for a total of 88% from the three.

Looking out to the year 2035, EIA projects US. electricity demand growing from 4 trillion KWH per year to 5 trillion KWH per year.  This is a growth rate that roughly mirrors the Census Bureau projections for US population, growing from 310 million people now to 389 million by 2035. 

Two areas that might cause EIA projections to be low are electric vehicles, which will increase home use for overnight charging, and a shift way from fossil fuels for home heating.  Let’s assume, though, that the EIA projections are accurate. 

By 2035, EIA projects the relative contributions from coal, natural gas and nuclear to be about the same: natural gas increasing to 25%, coal dropping to 43%, and nuclear dropping to 17%.  Renewables, of which hydropower is currently dominant, are forecast to grow from 10% to 14%. That growth will come from wind and solar as hydropower will obviously remain flat.

With the counrty needing 5 trillion KWH per year, reaching the goal of 80% “clean” means we need 4 trillion KWH per year to come from the clean category. Obviously, counting natural gas and nuclear as clean makes the goal a lot easier. Now, all we have to deal with is cleaning up the 43% portion from coal, meaning, get rid of the carbon dioxide emissions. To reach the 80% number, all we really have to do is to get half the coal, at least 1 trillion KWH per year, into the clean category. 

Fans of wind and solar will be saying at this point: wait, we don't need coal, just put more resources into wind and solar. Perhaps that could work, but there are those who say wind and solar will have their work cut out for them just getting renewables up to the 14% number. 


Reading between the lines, then, we might expect to see more than a few clean coal ads cropping up in the future.


from EIA 2035 Forecast

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