I often attend gatherings and events that have an environmental theme: it is not only part of my personal evangelism as an environmentalist and nuclear advocate, it is also simply enjoyable to discuss things with smart people who share some of my interests and concerns. Yesterday I attended a presentation that was somewhat different, in that the presenter conducted several interesting (and benign) experiments using the attendees as subjects. I won’t go into the details, but will just comment that the aim of the presentation was to introduce ways to encourage behavioral changes in others in order to promote sustainability.
The presentation was two hours long, and held in a room with overhead fluorescent lighting. I wondered at one point how to calculate each attendee’s attendance carbon footprint, based just on the emission intensity of the electricity powering the lights.
The lamps were 40-watt fluorescent bulbs, in six recessed protected ceiling fixtures each containing two bulbs. All the bulbs were operating for the duration of the event.
That works out to 12 bulbs, each consuming 40 watts of power for two hours = 12 x 40 x 2 = 960 watt-hours, or 0.96 kilowatt-hours.
That was grid power, so how much carbon came with those 0.96 kWh? Ontario’s grid is fed by five main sources of energy: coal, gas, hydro, nuclear, and “other” (mostly biomass).
What was the mix of energy sources between 1900 and 2100 yesterday? According to my database, it was the following:
|Fuel||Output (kWh)||CO2, metric tons|
As you can see, the total grid generation during that period was 37,274,000 kilowatt-hours, and the fossil sources—mainly gas but also coal and “other” (mostly biomass but some gas as well)—emitted 4,865 metric tons of carbon dioxide (CO2), the principal man-made greenhouse gas. You can see that nuclear was by far the single biggest producer; it accounts for nearly half the power produced over the two hour period.
So the emission intensity of the Ontario grid, in grams of CO2 per kWh during those two hours was 4,865,000,000 grams of CO2 divided by 37,274,000 kWh, which equals roughly 130.5 g/kWh.
How much power did the overhead fluorescents use? From my calculation above, 0.96 kilowatt-hours over the two-hour presentation.
So, with an emission intensity of 130.5 grams of CO2 per kWh in that period, the overhead fluorescents in the presentation room came with a carbon footprint of roughly 125.29 grams of CO2.
About 20 people attended the event. So we could say that each one of them had a carbon footprint of 6.27 grams of CO2, from his or her use of electric powered lighting.
Now, is that high, low, average? It all depends on which grid the electricity is coming from. The presentation was in Ottawa, Ontario. If it had been held across the river in Gatineau Quebec, each attendee’s carbon footprint from electric lighting would have been much lower. Quebec’s electricity has by far the lowest CO2 per kWh: something like 8 grams. So each attendee’s carbon footprint would have been 0.4 grams.
But what if the event had been held in Alberta, where the grid is primarily coal-powered? The CO2 intensity of Alberta grid electricity is around 900 grams—yes, nearly a kilogram—of CO2 per kWh.
So each attendee’s carbon footprint in that case would have been 45 grams, seven times what it actually was.
The mix of sources feeding the grid makes a huge difference to electricity conservation efforts.
At one point, the presenter asked the attendees to write down as many “sustainability” ideas we could think of. Knowing what I know about the Ontario grid, I of course wrote “Promote Nuclear Energy!”
I hope I was not the only one.
Re: “If you really love this planet, what actions would you take to keep it in balance? Too many “green” advocates call for a mix of unreliable “clean” energy which requires backup by heavy emitting fossil fuel…”
Steve, please tell me since you’ve run the circuit — Why are SO many nuclear advocates shy of outright calling anti-nuke greens health/safety Hypocrites — backed by factual charts of nuclear’s historic mortality/public damage scores compared other energy sources and industries for generations? Yea — make the audience gasp making that bold assertion; is being PC “polite” going to make them loathe nukes any less? It’s long due time to call a spade a spade and take the gloves off! Maybe it’ll jar their eyes open wider!
There are now reliable ways to use renewables.
The DOE has research on the effects of wind power variability – it’s not the problem some ill-informed people pretend.
I have been keeping an eye on grid tests of Solar with battery storage. These tests use battery storage that is now commercially available.
there are quite good studies showing how to go to 100% renewables.
We can’t go 100% nuclear without causing global warming in the near future anyway.
For all the spin from the nuclear industry the problem with climate change is not the CO2 – the problem is the rise in energy in the system.
Nuclear adds energy to the system and Wind/Solar don’t, unless you put the solar arrays in space.
So sorry – but the arguments such as yours James Greenidge are outdated and short sighted. You are promoting a path to global warming and denying the real physics of renewables.
What do you want to do with the current generated by photovoltaics? Use it, or store it?
The problem with solar is not “we can’t store it.” The problem is, it gives an even worse capacity factor than wind, which is bad enough. That’s because of physical realities like cloudy days and the planet’s rotation about its axis.
So on the rare instances where photovoltaics are generating current, your solution is to store it? Fine, but while the solar panels are topping up batteries, something else has to power schools, hospitals, the internet…
“mix of unreliable “clean” energy which requires backup by heavy emitting fossil fuel. ”
A single Wind farm needs backup. Solar in one area without storage needs backup.
Backup does not have to be fossil, yes often it is currently Fossil but your argument is like saying Nuclear needs fossil cause sometimes it is offline.
All grids run at above actual demand and burn fuel above what is necessary, but gas as backup for solar/wind does not burn at the level of the demand, it is turned down until needed.
Better modelling of the variability is improbing management and any waste burning for sudden increase.
Wind in one area can back up wind in another. Solar can back up solar if the grid allows it across a larger area.
This is all based on DOE research – you know them – the Nuclear power people.
Oh and you may notice that even Areva is heavily invested into solar and other renewables.
Richard, thanks for taking the time. But it’s not rubbish — it’s just physics and math plus economics. Wind’s dismal capacity factor, between 30 and 40 percent, is why its economics are similarly dismal. To approach statistical certainty of having wind provide power on demand, wind turbine fleets have to be so ridiculously overbuilt that there would be few areas without them. And even then, there’s still no certainty! Do you really believe this is practical?
If you are against nuclear, then you favour fossil. Pure and simple.
Wind fields DO correlate over large areas. A weather pattern, like a large high pressure system, can cover more than half of the continent for a several days at a time. So, what you suggest – that a stable all-renewable grid is possible – is simply not supportable by the evidence.
For sake of argument, lets assume we can overcome situations of low wind speeds over huge areas. We would still need to overbuild capacity by at least 4 x’s (assuming 25% capacity factor) and a supergrid that is likewise overbuilt several fold to be able to move huge amounts of excess power across the continent to make up for “local” variability. Ontario has a demand of ~20,000 MW. That would require 80GW of wind turbine capacity, or 40,000 2MW turbines. Land area requirement would be about 40,000 sq. km. (one turbine on a 1km x 1km grid EVERYWHERE). That would carpet THE ENTIRE LANDSCAPE from Windsor to Cornwall. Even if we wanted to pay the enormous cost of such a project, it simply wouldn’t be possible to use that much land (each turbine would need an access road, for example, so land use is not insignificant per unit).
The capacity factor for solar is about 1/2 that of wind. In the winter, much less again.
Thinking that we can run modern civilization of wind turbines and solar panels alone is a dangerous fantasy because selling solutions that are ultimately unworkable will simply push back the time at which we will actually achieve a decarbonized grid.
Rather than fantasy, lets look to what has been proven to actually work. France went to an 80% zero-carbon grid by means of a massive nuclear build, and achieved this in about 20 years. France has the lowest carbon intensity grid and lowest cost electricity in Europe. If that’s not proof of a workable approach, I don’t know what is.
I suggest you download (free pdf) and read the following:
MacKay, David: Sustainable Energy Without The Hot Air.
Dr. MacKay is not pro-renewables, he is not pro-nuclear. He is pro arithmetic. The implications of low energy flux density, unreliability, low capacity factors, lack of scalability of energy storage, are serious limitations to wind and solar and he “does the math”. When one does the math, and considers a world needing much MORE energy with burgeoning demand from the developing world, certain conclusions are inescapable. Conservation at the margins and making the grid a little less CO2 intensive with wind turbines cannot make a dent in the big picture.
About the author:
David MacKay FRS is a Professor in the Department of Physics at the University of Cambridge. He studied Natural Sciences at Cambridge and then obtained his PhD in Computation and Neural Systems at the California Institute of Technology. He returned to Cambridge as a Royal Society research fellow at Darwin College. He has taught Physics in Cambridge since 1995. Since 2005, he has devoted much of his time to public teaching about energy. He is a Fellow of the Royal Society. Nine months after the publication of ‘Sustainable Energy – without the hot air’, David MacKay was appointed Chief Scientific Advisor to the Department of Energy and Climate Change.