Ok, I can see your argument, let me repeat it back to see if I got it right.

You argue that by being physically near the Columbia river, a hydro electric plant can be constructed which generates power and sends it directly to a Google data center. But their other properties, some of which are nearer power plants which generate power using fossil fuels can not be considered to be using renewable energy. Is that about right?

If so, I see it a bit differently, if Google builds a concentrated solar plant in the Mohave Desert and that plant puts adds 1200MWhrs of energy to the Western Grid every month, and Google's real estate in California consume 1000MWhrs of energy from the grid every month, I can see that being claimed as using 100% renewable energy. There isn't a specific path of the electrons to the Google buildings but in that scenario Google will have added more energy through renewable sources into the grid than they extracted from the grid[1]

I've got Solar panels on my house and they generate more power during the day than I can use, they generate no power at night. I have them connected to the grid. When I'm generating excess power its probably being used by my neighbors but somewhere nearby a fossil fuel plant is using less fuel because of the power I am feeding into the grid.

Because is is set up this way, PG&E bills me on an annual basis and on that basis the 'net' amount of energy my house uses is quite small, in terms of ratios, over 90% of my total electrical energy usage is accounted for by the energy I generate on my rooftop. I think of that as "90%" of my energy comes from renewable sources, even though every night, at that moment, I'm using fossil fuel sources (or simply the grid). Once I have a couple of PowerWall's install it will get a bit more explicit but I consider both interpretations valid. I'm guessing from your argument that you do not.

[1] You can also argue that the 2nd law of thermodynamics tells us that adding it and then removing it will leave a bit behind so perhaps a draw of 1MWhr might need an input of 1.2MWr in order to offset grid losses to radiation and heat.

> I'm guessing from your argument that you do not.

Frankly I don't think anyone should. It's mental gymnastics to be able to say you aren't using dirty energy when you really are.

Let me illustrate with an example of why you can't get by with 'offsets'.

Let's say Arizona is running on 80 GW natural gas and 20 GW solar. Google wants to build in Virginia, which relies heavily on coal.

So they bring online a 2 GW datacenter in Virginia which is powered by a 2 GW increase in coal burning. They "offset" it by building 2 GW of solar in Arizona, which scales back natural gas by 2 GW.

The result of their 'clean offset' has been the conversion of 2 GW natural gas to 2 GW of coal, which is significantly worse for the environment.

I see what you're saying, but to me trying to phrase it in that way seems more like mental gymnastics than actual double entry accounting in watts.

Would it help if the renewable source had to be connected to the same grid-tie (there are 4 I think in the US) ? Then you're putting renewable energy into the same grid you are pulling it out of.

What if your solar plant in Arizona use the Fischer–Tropsch to make fuel, then you drove it in a tanker across the country and poured it into generators in Virginia?

The way I see it is that watts are watts (just like dollars are dollars) so if the total watts you burn are offset by renewable watts you have put in, then you are ahead. If everyone does that then by definition the entire grid is running on renewable energy.

>Then you're putting renewable energy into the same grid you are pulling it out of.

Right, but they aren't connected to the same grid. Google has datacenters all over the world, connected to all sorts of different grids with different source compositions.

>What if your solar plant in Arizona use the Fischer–Tropsch to make fuel, then you drove it in a tanker across the country and poured it into generators in Virginia?

Sure, but you have to account for the emissions from that whole process as well (emissions of solar + emissions of generating the fuel + emissions of transportation + emissions of burning the fuel).

>The way I see it is that watts are watts (just like dollars are dollars)

Nope, a watt generated on one grid does not spend on another because they're not all interconnected.

Until we solve the energy storage problem, the problem is exacerbated further by continually expanding solar installations in one particular region of the US that will generate more than the consumption for part of the day.

One small point I realized reading your comment here is that you mentioned emissions. The original article is about "renewable" energy, not "carbon footprint neutral" energy. If you had a wood fired power plant, it would be 'renewable' energy, but it would not be 'carbon neutral'. I think it is important to distinguish between the two and both are important.

Ok, if we throw out emissions and just worry about renewable, then the trucks traveling across the country have to also run on the fuel generated by the solar panels for your watts to be fungible across grids.

Well there is no reason the trucks couldn't, it would just affect the overall efficiency (the amount of solar power in to the amount of electricity out).

Actually nuclear power can be used to make breeder reactors, which uses the neutron flux from a critical reactor to create more fuel, in theory giving them a lifetime that is at least as long as the supply of heavy elements holds out, but if you want to be seriously pedantic then Solar isn't exactly renewable since the Sun has a limited amount of hydrogen to burn and once it runs out it will be very hard on our planet, catastrophically so by all estimations.

There are basically two numbers here:

1. Net usage after selling off excess energy 2. Net usage assuming there is no demand for excess when you have it (maybe everyone on the grid has solar panels)

Achieving 100% in #1 is great and I applaud Google for it. If everyone did this we could drastically reduce overall usage of fossil fuels, but I believe the fear is that people won't know the distinction and will assume "if everyone does what Google does we will all be 100% renewable" and that isn't true.

Can I test an assumption with you? Lets say that "everyone does it", and by that I mean literally everyone on the planet generates more renewable energy on some grid somewhere, than they use on the grids they are using.

That is the definition of 100% renewable energy use is it not? You can't push power into a grid if nobody is using it, they don't work that way. So if the world is using 12.3 TW and 12.3TW is being generated by renewable sources, your done.

If I'm generating 20% more solar energy than I need and resell the excess it to the grid, am I operating at 120% renewable energy?

What about the consumers of my excess energy? Are they operating at 20% renewable and 80% fossil?

If my 20% in excess is counted towards my total renewable energy consumption, and other consumers also claim that 20% towards their renewable consumption, then we're just double counting. No?

One of Enron's many schemes involved creating a logical abstraction layer across physically partioned grids.

I think the lesson learned from that scandal is to keep it simple. On a per grid basis, simply acknowledge that fossil fuel accounts for X% of power, and rally the community behind an honest metric.

Headlines claiming 100% "mission accomplished" will lull most people into a false perception.

While I agree with your base argument, I would argue further that the (substantial) transmission losses at least in the consumed and perhaps in the generated energy also need to be factored in, so a simple x:(x+1) relationship is not quite sufficient for a robust claim of "100% renewables" which is based on offsets.