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Comment by badestrand | Hacker News Reader

I would love to see a complete cost comparison with solar.

1.5 MW is nothing to scoff at, so if it costs a bit in maintenance that's okay. But overall costs would be great to know.

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One benefit that’s difficult to quantify is that the power is extremely predictable compared to other renewables.

It can be quantified by comparing it to the cost of solar or wind plus storage.

It’s not straightforward though is it. It depends on your base load profile, your ability to time shift loads, what level of modal and geographic aggregation you have etc. i.e. not something you can just stick into an LCOE calculation and call it a day.

> It’s not straightforward though is it.

Sure, there are many parameters to consider, but it's the kind of thing energy analysts do all the time.

1.5mw is likely a nameplate capacity for the turbine, not the actual output (which should be labeled in GWh per year).

The article likely double-dips on this by saying that 6MW could provide for 7k homes, which it obviously can’t at peak use.

Why is it obvious that it can't? I just looked up the numbers and Scotlands absolute peak demand is 6.5 GW and there are about 2.5 M households. With those numbers they would need 18MW for 7000k households, but that ignores all commercial contributors to peak demand (I could not find data on commercial vs residential demand), but it seems to me the number isn't completely off.

Also I would say the expression "powering a home" usually implies average demand not peak demand.

Well, with 6.5 GW for 2.5M households, you’re at a peak around 2.6kW per home.

Assuming these turbines are always at nameplate production, which they are not, they produce 6MW. Spread among 7k homes, that’s less than 1kW, which is not a lot.

Given the previously stated peak of 2.6kW per household, 6MW would cover about 2300 homes.

The only way you could get to this kind of number would be if you calculate the average use for a household over a year. But then you would have to compare it to the plant’s yearly production rather than its nameplate capacity.

Wikipedia quotes MeyGen at 10.2GWh in 2023, that means 1.14MW on average instead of 6MW. Assuming perfect storage, that would mean an average of 163W per house for 7000 houses. That is barely enough for a fridge.

> Also I would say the expression "powering a home" usually implies average demand not peak demand.

That's my issue. Comparing average demand to nameplate capacity is dishonest.

It was you that decided it was nameplate capacity. The actual statement is "producing" 1.5MW. Tidal flows are sufficiently predictable that it's not an unreasonable expectation to have reliable power outputs.

The 1.5MW number is what the generator is rated for according to the company building them [1]. i.e. it's what it's supposed to produce in ideal conditions according to the spec. Or, colloquially, the nameplate capacity.

> The actual statement is "producing" 1.5MW.

I have no doubt that the author could write that. My message points out that it simply is not true.

[1]: https://simecatlantis.com/wp-content/uploads/2016/08/AR1500-...

> That is barely enough for a fridge.

An efficient European fridge uses less than 250 kWh/a, or less than about 30W on average.

E.g. this uses 127 kWh/a: https://www.bosch-home.com/de/de/product/kuehlen-gefrieren/k...

> Assuming these turbines are always at nameplate production, which they are not, they produce 6MW. Spread among 7k homes, that’s less than 1kW, which is not a lot.

In many countries, 1kW is more than enough to cover electricity usage in a household. https://ec.europa.eu/eurostat/statistics-explained/index.php... says “Electricity consumption per capita in the household sector in the EU in 2022 was 1.6 MWh per capita (1 584 kWh)”.

That’s about 4.3kWh/day or 180W. https://ec.europa.eu/eurostat/statistics-explained/index.php... says there were 202 million households in the EU in 2024, on a population of about 450 million, or 450/202 ≈ 2.2 persons/household.

So, on average, a household in the EU uses less than 500W of electricity.

The issue pointed out is that you're comparing average power use to maximum theoretical production. These houses are going to peak way above 500W.

If you want to compare power use of a household averaged on a year to yearly production of these turbines:

- 1.6MWh * 2.2 people per house = 3.5MWh/household

- 10GWh produced in 2023 / 3.5MWh = ~2860 households supported.

Average electricity usage in the UK is something like 2700 kWh/y [1], which is a bit over 300 W on average. Most UK household energy use is gas.

[1] https://www.ofgem.gov.uk/information-consumers/energy-advice...

I didn't understand why UK government numbers [1] were different from ofgem's numbers, apparently the government uses mean electricity usage (total power use divided by # of households), while ofgem uses a "typical" number which is based on median values.

[2]: https://assets.publishing.service.gov.uk/media/67e3eae39c9de... - see background section

Also there is theoretically power in the GW range to be harvested here (specifically, Scotland’s tidal flows), so it’s worth investing a substantial sum to figure this tech out.

Texas’ capacity was 113000 MW yesterday so 1.5MW doesn’t seem significant. Am I understanding this wrong?

https://www.ercot.com/gridmktinfo/dashboards

Why are you comparing a single turbine in Scotland to the entirety of the state of Texas's supply (thousands of turbines)?

hundreds of thousands.

Wrong comparator. 1.5MW nominal output is comparable to a large wind turbine.

For instance, there's the https://www.esig.energy/wiki-main-page/general-electric-1-5-..., which has ~40m blades. The AR1500 (which is what these tidal generators are using) is smaller, with "only" 9m blades.

So it's significant in that these aren't toy devices, they fit in a very similar place in the engineering ecosystem as conventional wind. They should be a real competitor.

In 2025, the large commercially deployed wind turbines are like 15MW for offshore and 6MW for onshore.

GE's 1.5MW models are 20 years old.

Can you even still buy new 1.5MW wind turbines?

Yeah, and a solar panel might only produce 250 watt, that would mean solar is also not significant /s

Are you really comparing a single experimental turbine's handwaved output with the consumption of an entire state with a population as big as the bigger European countries?

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