emix — archive

[David Holmberg]

So, I missed the emix meeting, so don't have those notes yet, but I want If I have local generation, PV · All I can measure is active and reactive power at the meter. · I can meter the solar panel, or mix it in with the house meter. · The utility can buy me a separate meter and pay me some premium price for my solar power, then they get the results certs. · They can pay for the solar panel and maintain it and then I am just leasing them my roof. If I want to use green energy, clearly I get whatever electrons are in the wire, pushed by the nearest and biggest power sources. If I have a solar panel on the roof with a crappy inverter, then I get low-quality green power. But, let’s just talk about what some grid-side service provider might sell me. They can offer me the “green power” option, which means they are trading RECs (certs whatever) in the background to make sure that the number of kWh I purchase is backed up with kWh produced at some wind/solar/hydro generator somewhere. They might have a RTP for this green power and communicate with that price the info about where that power came from, or the serial number on the RECs or something else. But there is no way to give me only green electrons, and there is no way (I suppose) to even say, for a given customer, exactly where the power IS coming from. If we pass cert serial numbers around, then we have traceability to where the power came from (assuming we don’t have multiple copies of the cert). How do RECs work, and what is the difference from that with a cert? What are we certifying? We could have a minute by minute meter history that puts a cert on each minute of power production. E.g., 31.52 kWh in the past minute (timestamped) with PV installation ID, etc. That becomes a fungible commodity. Physically that power is used instantaneously by nearby loads, spread about. But practically, some entity will buy that quantity of green power and throw the cert in a big bucket (let’s say it is the utility selling me green power) and make sure that the number of kWh consumed by all customers on the green power tariff is matched by the number of kWh certs in the bag. Am I anywhere close to reality? But we still haven’t discussed the time and price sensitivity. A cert is for a given minute where there was some specific local wholesale nodal price (or some relevant price). That 31.52 kWh of solar power on peak might be worth $30. The same power from wind at night might be worth $1. If we want to actually have a positive effect on CO2, pollution, energy reduction, then we have to buy certs from power produced on peak when the power it is offsetting is used on peak. And thus we have to have certs tied to time, with value of the cert tied to the price at the time the power was delivered. Where is that relative to reality? To where we want to go? So, you could sell me green power and send me cert IDs to prove it, but likely you won’t bother sending such info with my price signal—it’s really unrelated to the real-time price isn’t it? The price reflects the cost of power (or of greener sourced power), but isn’t tied to any specific generator. The cert says that some green power, with my name now on it, was produced at the same time I used some power. If I take Toby’s example of only running the fountain when the wind is blowing at the wind generator on the next mountain, then all I have to do is buy certs from that generator for power generated at the same time the fountain is on. What we need is a market interaction that allows completing that transaction on the order of the time the wind starts and stops so that I can know I got the power and run the fountain pump based on fresh certs. I don’t want to run the fountain at 2:05pm only to find out that the wind on the next mountain quit at 2:03pm, or that all the certs from the now diminished wind were already sold to someone else. So, then, if we envision being able to buy specific certs from specific generators, we are really talking about a local auction, no? Oh well, too many thoughts… David