So what is your carbon footprint?

Thanks, that is a very good point, anything we build has some form of impact.
And as long as, when comparing different types of plants, the same measurements are included, that is an excellent way to look at it.

What I was confused by was the term you used, "electric plant".
Power plants typically are called the fuel, not the output, (i.e.Hydro plant, Nuclear plant, etc) so I wasn't sure what it was you are talking about.

 

So - (not that anything in the hydro-CO2 article is based on real data) does that leave PV & wind, as the least environmentally damaging?
.

 

So much so, it is a no-brainer.

Are you a reader of Amory Lovins ?

 

That article is discussing an episode of the Fully Charged video podcast called "Volts for Oil". I wrote about it here:

My Nissan Leaf Forum • View topic - Pollution: EV vs ICE

If you follow that link you will see that all of the key allegations that Robert Llewellyn makes are grossly misleading.

I pick the details apart and demonstrate that when you calculate the electricity kwh per gallon of gasoline the actual number for UK refineries using UN statistical data is about 0.2 - 0.3 kWh of electricity, not 4.5 kwh.

Stated another way, only about 5% of the energy used to refine a gallon of gasoline comes from grid electricity. That's very much in line with estimates of 3.5 - 5.2% for US refineries based on Dept. of Energy statistics.

More here:
how much electricity is used to refine gas?

 

Long discussion (not to mention very long discussions in past similar threads) over a question that was already answered by EPA in "beyond tailpipe emissions" section of fueleconomy.gov (as cited by others here).
No doubt - an emotional issue

 

I'm not knocking on you either, but 36-45% for real world natural gas plant efficiency is extremely low. Real world efficiency for natural gas in CA is ~46%, including lower efficiency load following and peaking generation and ignoring CHP. A typical baseload plant is better than that.

SAS Output
SAS Output

In addition, those electricity/natural gas figures were for California, not the US as an average. It's certainly possible that the upstream emissions associated with gasoline are lower in the US than in CA, but it doesn't change the story much.

Keeping in mind that I was comparing the additional energy requirements (electricity/natural gas) to the energy content of a gallon of gas, 40/178=22.4% is pretty close to ~25%. One gallon of gas is 37.5kWh, so 22.4% represents an extra ~8kWh associated with the production of that gasoline.

This is far higher than my ~4-5kWh of usable energy figure, and that's because of the ~50% energy penalty converting natural gas into electricity. Still, it's close enough for jazz. You can go with 4kWh instead of 5kWh, but ultimate you're looking at ~16+ miles of free EV operation just from the electricity and natural gas it took to produce the average gallon of gasoline.

Not to say that there aren't areas with really dirty electricity. Those would be better for a Prius C if the owner didn't or couldn't put in renewables. Having said that, in many places, the i is around half of the Carbon emissions of the C. Locally, an i would emit a ton/year less than a C. Both cars cost about the same new, so someone that can swing an i in my neck of the woods would significantly reduce their GHG emissions.

 

That's definitely accurate. It's also a straw man because it's only looking at a specific type of energy used (electricity) at a specific stage in the production process (refining). Refineries don't only use electricity, they also use natural gas. In addition, extraction uses electricity and natural gas. There's also transportation, flaring, etc... But there isn't as much info published on those, so we'll ignore them for now.

In CA, refineries use ~7,000 million+ kWh of electricity for ~15 billion gallons of gas and ~27 billion gallons of refined fuel (diesel, gas, kerosene, etc...). If we take the whole barrel, that's ~ which is ~.25kWh of electricity per gallon. They also use a lot of natural gas. 1,000+ million therms, which is ~30,000 million kWhs. After converting that into electricity at a natural gas power plants, that's something like ~15 million+ kWh of electricity. All told, we're at ~.75kWh of electricity at consumers homes from the refining process.

The remaining 3+ kWh/gallon come from extraction. Pulling ~13 billion gallons of oil require 3.846 billion kWh of electricity, which is another .25kWh/ gallon. The real sucker punch comes from natural gas use in extraction. ~2,900 million therms is ~85 billion kWh for ~13 billion gallons of oil. Even after we convert it to electricity, that's still ~42 billion kWh, or ~3.2kWh/gallon of oil.

That adds up to 4+kWh per gallon of oil. It's actually higher because we aren't including the energy we need to find the oil, the energy we need to get it from the well to the refinery, and the energy we need to get it from the refinery to the gas station, but you get the idea. Add in the natural gas lost to flaring, and that's a lot of energy we could be using to power EVs going into the production of gasoline.

http://www.evnut.com/docs/cec_petro_industry_power.doc

 

Where I live in Ohio, each of my Prii have a smaller carbon footprint than a PIP or an all-electric car like the Leaf. The majority of the electricity here is generated by coal.



I've got to move...

Bill the Engineer

 

Seattle City Light has claimed to be 'Carbon 'Neutral' since 2005. While it does get a smidgen of fossil carbon generation from BPA, it buys enough carbon credits to offset both that generation and the emissions of its motor vehicle fleet.

Its latest Fuel Mix Report shows 1.7% from coal in 2013. This is a revised figure, nearly double the original report. The original apparently was based on a miscalculation from the state. I haven't seen the full story, nor know if they bought additional credits to cover the revision.

To get this 'carbon neutral' electricity, you need not live in Seattle proper, the utility serves several surrounding communities too. But the region does have a significant amount of coal, and the private utilities are last in the pecking order when choosing sources, so they are stuck with the carbon that the public utilities can reject. And they serve much of the regional population. In a sense, this shifting and shuffling is just bookkeeper handwaving.

 

Peaking and load following natural gas plants are guaranteed to run at a lower load capacity than coal, not baseload nat gas.

Jet Fuel is also higher than that. 39.5kWh according to the chart below. Gasoline is 36.3 there, so a little smaller than the figure provided by onlineconversion, but closer than the figure you provided, 32.4kWh, which is for E10, 90% gasoline/10% ethanol.

Energy Content in Common Energy Sources

http://fuelsinstitute.org/ResearchArticles/E85_AMarketPerformanceAnalysisForecast.pdf

All told, that's ~4+kWh. The discovery/distribution of nat gas is << than that of oil, and there's a shorter supply chain since it doesn't need to be converted into another product before use, so I imagine we're still looking at 4+ kWh/gallon after the fact.

Either way, whether it's 15+ EV miles/gallon, 16+ EV miles/gallon, or 20+ EV miles/gallon, there's a lot of energy used in gasoline production that could be used to directly move an EV many miles before the gasoline car fires up. In coal heavy states, an EV can still produce more GHGs, so there's a compelling argument for a Prius C, but in other places, the C is substantially better in terms of GHG emissions.

 

Exactly.

I pass oil rigs pretty often, and they are burning off NG -- as waste. No profitable way to bring it to market. So unless the NG used in petrol processing is demonstrably from the grid the presumption that the fuel could have been just as easily burned in a high efficiency power plant is a BS argument.

 

Yes. Studies have found that over a 20 year timeframe the CO2 impact of NG vs coal is not that different. This is because NG is almost entirely methane and methane is a powerful global warming gas. After 10+ years in the atmosphere the methane is eventually broken down into CO2 (less than coal would have emitted) and has a reduced impact so over a longer period of time like 100 years NG is much better than coal.

My impression is that most of the methane leaks occur either in the gas fields after drilling or in the local distribution pipes and both cases can largely be mitigated with a little regulation.

Apparently most of the gas field leakage comes from valves accidentally left open or leaks in the field pipes. The leaks are not obvious to human observation because methane does not naturally have a strong odor and is also invisible. It can be seen leaking into the air using modified imaging cameras or detected using methane sniffing equipment. Regulations could require installation of that equipment with remote monitoring.

The local "last mile" distribution pipes that leak are mostly old cast iron pipes installed decades ago in big cities. They need to be replaced with modern plastic lines. I know PG & E is doing this in the SF Bay Area but it might motivated by earthquake concerns more than global warming considerations.

 

A VERY hot spot, but I gather the coal mining in the region is a major contributor.

The honest conclusion in general is that fossil fuels are bad.

 

The 32.4kWh figure you're using is for E10, not straight gasoline, which is what refiners actually produce. Using your own math (which I'm pretty sure is incorrect, but whatever), you still end up with 4+ kWh using your 50% efficiency figure and the energy value of gasoline instead of E10.

Don't blame others if you can't figure out the different between E10 and RUG or how to adjust your own figures.

Anyhoo... You're also confusing the EPA's estimates with the actual gas and electricity consumption measurements by the oil industry for refining/extraction. At least in CA, the EPA's estimates are relatively low. They might be more accurate for the country as a whole, but the ANL estimates using GREET are also higher, so it might be that the EPA estimates are just low.

That's a valid, although those leaks are probably similar for both processes. I agree that we need to do more to stop fugitive methane emissions.

Now I know you're trolling. EVs already have replaceable packs. Hybrids do too FYI! I pulled mine, swapped a pair of modules, and had everything zipped up in 3+ hours.

But yeah, sure EVs are so awful, just like hybrids were so awful. Nice to see astroturfing in action!