How do buildings with eco-electricity know their electricity is eco?

Question

Walking around the city centre of Warsaw I saw a poster placed by a construction zone of a new skyscraper. The poster said something along the lines "our building will use electricity from windfarm in XYZ Norway". (I can double check tomorrow.)

I started wondering: how is that possible? I highly doubt that there is special very long cable that runs from Norway to that very building in Warsaw.

I presume that there is some big electricity distribution centre in Poland and that distribution centre buys some energy from that wind farm in Norway. If that's the case, then the poster is just a scam. Let me portray that with an example. Being in Australia and saying: "oh you there, oh come here and taste this amazing lemonade that was made with water specially gathered on the beach in Mexico". Where in fact water was just a regular tap water sourced in Australia.

Looking forward to a conversation :)

Answer 1

I don't think it's a scam.

It is certainly true that there is no way to control - or even to know - where a particular "bit" of electricity came from. But electricity is a generic commodity - within an electric grid it's all the same voltage, same frequency, same phase angle. None of it is better or worse or different than any other. Nor is it labeled or tracked in any way. The grid accepts it from all the generators, and distributes it to all the users.

Some states within the U.S. have deregulated electricity systems, where the generation facilities are owned by various companies, and the utility company handles the transmission and distribution, and billing. In these areas, customers can choose their supplier based on price or any number of other criteria, which can include the energy source. The various suppliers all feed their electricity into the grid, and the utility tracks the energy supplied by each generator and energy used by each customer.

The utility also must have a system for reconciling the production by each generator with the consumption by all of their customers, to ensure everyone is meeting their commitments.

In a system like this, each generator will supply the amount of energy that its customers consume - no more and no less. If one generator is a nuclear power plant, another is a coal plant, and a third is a wind farm, and 20% of the customers buy their power from the third supplier, then the wind farm is supplying the energy needs of 20% of the customers. If more customers sign up for wind power, the supplier will increase output to meet their new demand, and the other two suppliers will operate their plants at lower power levels.

If the wind stops blowing, the coal and nuclear plants will increase output temporarily. Then when the wind picks up again, the wind power will be increased to a higher level than their customers demand in order to make up for the power they didn't supply. In the end it will all balance out.

So are the particular electrons that are used in a building actually supplied exclusively by the wind farm? No, but the wind farm does feed into the grid the amount of electricity that the building consumes. And if the building management changes it's mind and decides to use nuclear power instead of wind, the wind plant output will go down and the nuclear plant output will go up by the amount the building uses.

Answer 2

our building will use electricity from windfarm in XYZ Norway

No it doesn't.

Firstly, all electricity in the grid is mixed. It is completely impossible to say that a particular building gets its electricity from a particular generation site.

Theoretically, an electrical engineer could calculate how much the load at every generation site increases if a new electricity consumer is added to a certain location of the grid. However, the answer to this is very clear: a consumer uses electricity mostly from nearby generation sites, and very little from far-away generation sites.

Also, what if the connection of the wind farm XYZ to the grid fails? Does the building have a contract that says the building will automatically be isolated from the grid to prevent it from using electricity from other sources? Most likely it doesn't. Because it doesn't, it uses electricity from whatever generation sites may be available.

Furthermore, even a claim that a particular building uses "wind electricity" is bogus. What if it's a windless day? Do the lights in the building turn off then? No they don't. And because they don't, the building doesn't really use "wind electricity".

Usually claims about using "wind electricity" are made in the following way: a building consumes X kWh, and it buys X kWh from wind power. However, those X kWh:s are generated and consumed at different times, and since the grid doesn't yet have a good and plentiful way of storing energy deployed in large enough scale (today the largest-deployed storage is hydropower but we don't have enough of it), it's actually very likely that even though X kWh:s of wind power were generated, the building partially used fossil fuel generated electricity.

Maybe someday pumped storage hydro will be built in large enough scale to mountainous areas. A paper in Nature Communications claims that we have enough suitable sites. Also, hydrogen can be stored underground. The problems of hydrogen however are that the round-trip efficiency from electricity to hydrogen to electricity back again is about 35%, i.e. not very good, and that the turbine / combustion engine power plants that convert it back to electricity are needed so rarely but still have to be paid for, that you can expect price of 200-300 USD/MWh for hydrogen electricity.

One solution that is available near the equator is solar cells and lithium ion batteries. For wind power, battery storage doesn't work since there can easily be 2-3 consecutive weeks with poor wind, but solar power is more consistent and even during cloudy days you get about one fourth of the energy you would get from a sunny day, whereas on a windless day you would get nothing from wind power. So you can charge a battery daily and discharge it nightly. Far away from the equator, the problem is that there's so little solar power available during winter, so solar + batteries doesn't work far away from the equator.

So you're right. The claim is a scam.

However, if there was a special cable from the wind farm to the building, then it wouldn't be a scam. But then if the one single cable gets damaged or if winds at the wind farm are poor, then the building would experience a blackout.