
UK sees longest period of negative power prices - jbmorgado
http://www.argusmedia.com/news/article/?id=1474697
======
austinl
I'd recommend the book _The Grid_ as a primer on how stuff like this can
happen. Energy is strange, in the sense that everything produced needs to be
used more or less immediately. Maintaining the energy grid is a careful
balancing act between preventing surges and blackouts.

There are a lot of grid-related engineering problems that come from increasing
decentralization (e.g. wind, solar, hydro) because it increases
unpredictability in supply.

[https://www.amazon.com/Grid-Fraying-Between-Americans-
Energy...](https://www.amazon.com/Grid-Fraying-Between-Americans-
Energy/dp/1608196100)

~~~
oh_sigh
Bought the book, but spoil a little for me if you would: I know that some
utilities turn on pumped hydro storage to handle excess capacity, but what
other ways are there to efficiently waste energy?

~~~
petre
Flywheel storage for wind energy. It's mostly used for grid balancing.

Beacon Power has a complete solution but they went bankrupt in 2012, then got
bought by Rockland Capital who intend to rehire the staff and build a 20 MW
plant in Pensylvania.

Also, here's an article of such an energy storage project in Ireland by
Schwungrad Energie Ltd.

[https://www.rte.ie/news/business/2015/0326/689945-renewable-...](https://www.rte.ie/news/business/2015/0326/689945-renewable-
energy-storage/)

~~~
epistasis
Right now and for the foreseeable future, lithium ion batteries are a better
alternative to flywheels, though they will see some use for applications that
require high power but little total stores energy.

The power:energy ratio is high, but has few applications on the grid. Even
lithium ion's typical 4:1 MW:MWh is a bit high.

The really unexplored territory is seasonal storage. Electricity to hydrogen,
methanol, etc. have huge round trip efficiency hits, like 30%-50%, but may
make a ton of sense.

------
arunpn123
Ah finally something I am knowledgeable about.. building a software simulation
system for a smart power-grid that can account for renewable energy sources
was my grad school research project. Linked here if you wanna learn more:
[http://arunpn.com/projects/aces-co-
simulator/](http://arunpn.com/projects/aces-co-simulator/)

~~~
gub09
Someday, there will be a topic on HN about which I too am knowledgeable...
someday.

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Nav_Panel
Perhaps I'm not fully understanding how this works, but could one conceivably
run a business whose only product is predicting when the price will go
negative and "wasting" power?

~~~
manacit
Perhaps not just when prices are negative, but it's not an uncommon practice
to 'store' power by pumping water uphill when it's cheap and demand is low
(generally at night), and then using that potential energy to generate and
sell it when electricity is more expensive.

I have absolutely no clue what it would take to make that profitable, but it's
a strategy for handling the natural spikes of demand when using power
generation methods like solar and wind that are unable to adjust quickly to
changing demand.

~~~
Baeocystin
>I have absolutely no clue what it would take to make that profitable

You need a large watershed with a wide range of useable head. It is an
excellent system when the geography and hydrology allows for it.

Unfortunately, such areas are not common or evenly spread, and are not really
possible to economically construct without a great deal of cooperation from
the local geology.

~~~
AdamJacobMuller
You also need one where you're given significant environmental carte blanche.
These types of projects are similar to dam projects in the scope and scale of
the amount of the environment that they destroy, times two as you need
upper/lower ponds.

~~~
abraae
Your lower pond could be the sea.

~~~
tsomctl
So then you're pumping salt water into (presumably) a fresh water lake. I
don't think that decreases the environmental damage.

~~~
abraae
Yep, your upstream lake should also be saltwater.

~~~
205guy
As the sibling comment shows, you can build an artificial lake large enough to
be feasible. The Okinawa plant seems to have been decommissioned for lack of
need (at its given cost). It was probably a victim of the current oil/gas
extraction boom and artificially deflated oil prices. Still, I wonder about
their ability to control costs due to corrosion--salt water is horrible for
this reason.

~~~
Baeocystin
I couldn't find much more about the site in English, but considering how
expensive the lining must have been for what was a pretty small storage pool,
in addition to needing expensive materials like stainless steel and assorted
specialty plastics to deal with corrosion...

I can't know for sure, but regardless of whether they say it was due to weak
demand or not, I bet it was the saltwater issue that sunk the project more
than anything else.

------
ghouse
And it has been so sunny in California that electricity prices have turned
negative (late morning, temperate spring weather with low load, high hydro
output due to a wet spring)

~~~
ghouse
And you can watch at home:
[http://www.caiso.com/pages/pricemaps.aspx](http://www.caiso.com/pages/pricemaps.aspx)

~~~
205guy
The Internet and open data movement are just incredible. I am still amazed
that regular people can get such insight, and fairly well presented anytime
online.

------
TheSpiceIsLife
> for five consecutive hours ... as the grid was oversupplied owing to high
> wind generation during off-peak hours of low demand.

This is exactly the problem the detractors have with grid connected wind and
solar.

~~~
rpearl
I have two qualms about this claim: The first is purely economical. Does this
not simply indicate that there is insufficient supply of electricity _storage_
(ie batteries)?

The second is... wow, if excess supply of energy is a reason there are
detractors to wind and solar, then maybe treating electricity as a market is
totally misaligned with perpetuating sustainable human activity. Maybe we
shouldn't do that.

~~~
nine_k
The oversupply of electricity is not the cause of "detracing" solar and wind.
It's its undersupply on a winless overcast evening.

What we need is cheap (per GJ stored) longer-term electricity storage.

~~~
imron
Tesla Gigafactory to the rescue!

------
skookumchuck
This just means inefficient pricing. If prices were adjusted in real time, one
could schedule charging car batteries, heating water in the electric water
heater, etc., when prices are cheap.

~~~
paulddraper
Inefficient usage, not pricing

~~~
skookumchuck
Usage patterns follow pricing.

~~~
creeble
If only that were true for electricity. Nobody needs it at night, despite it
being cheap then.

~~~
skookumchuck
People charge their electric cars overnight. Water in the hot water tank will
stay hot for a couple days, so it makes sense to heat that at night, too.

In hot weather, you can also run the energy-hungry A/C at night to cool a tank
of water or a block of masonry, then use that during the day to cool the
house.

The reason nobody bothers doing that is because the price of electricity is
the same day and night.

~~~
Rebelgecko
Wouldn't the inefficiencies of doing that outweigh the cost benefits? Or is
night time power so much cheaper that it'd be worth it?

~~~
skookumchuck
Why would it be inefficient to charge your car battery at night? And storing
coolness in a masonry slab doesn't sound inefficient to me. Pumping water
uphill and running it back through a turbine is pretty inefficient.

~~~
Rebelgecko
I was referring to the cooling part, not the car charging. My totally
unsubstantiated gut feeling is that a piece of concrete or a tank of water
wouldn't stay cold long enough to be useful. With my local company,
electricity during the day is something like 20%-100% more expensive (less of
a differential in winter, more in the summer)

~~~
skookumchuck
Masonry as thermal mass in homes has been in common use for centuries, maybe
even millennia:

[http://www.greenbuildingadvisor.com/blogs/dept/musings/all-a...](http://www.greenbuildingadvisor.com/blogs/dept/musings/all-
about-thermal-mass)

------
basicplus2
These problems are fundamentally about the loss of what's called "spinning
reserve".

In a traditional steam turbine generator system, a number of generators are
run at well below fully capacity with a full head of steam in the boiler but
essentially ticking over.

When there is a sudden requirement for extra power signalled by a relatively
small drop in voltage, the inertia in the spinning turbine and alternator take
up the load as the governer opens the steam valve releasing as much of the
stored pressurised heated steam in the boiler to take up the load, as it is
the reduction of temperature of the steam that is the primary source of power.

The loss of so many steam turbine powered systems is causing the problem.

If these issues are to be solved it is about insufficient energy storage
systems such as inertial storage systems or batteries to take up the function
of spinning reserve.

~~~
snowwindwaves
Demand for extra power manifests as a drop in frequency not voltage.

~~~
basicplus2
Its both in Australia as strange as it may seem.

In certain parts of Australia Frequency is deliberately maintained throughout
a wide range of load demands which means it is by other means (magnetic
amplifiers) that voltage is used as the signal for power.

It is not until voltage signally cannot maintain the desired frequency that
the under frequency load shedding kicks in.

In fact the obsession with frequency is so high that over time beyond any 24
hour period (and thus even years) that an electric synchronous clock is
usually always within at most a few 100th of a second out, as the system
frequency is adjusted up and down to correct for accumulated errors.

As a result frequency control is spot on but voltage control is generally
pretty awful.

~~~
snowwindwaves
Use of load shedding or generation shedding to balance load and generation on
a grid are a different mechanism than the continuous adjustment of generator
output by the governor in response to changes in frequency that occur as
mismatches in real power demand and generation result in changes in the
kinetic energy of every synchronous machine.

Load shedding is triggered by underfrequency and undervoltage elements,
generation shedding is triggered by over frequency elements.

I am aware that in New Zealand the distribution utilities (especially in
Christchurch) perform 'peak shaving' to reduce the peak demand on some
substations by turning off people's hot water tanks using a ripple signal
injected on to the power system, but that is to alter the load profile not
perform frequency regulation.

Every large system operator attempts to balance the positive and negative
frequency errors from 60Hz to zero over a 24 hour period so that clocks are
correct, that is not unique to Australia.

Can you provide any links to how voltage is used to regulate the frequency in
certain parts of Australia? A magnetic amplifier is not a term I am
immediately familiar with. It almost seems to me like a normal synchronous
generator, where a current in the rotor causes a rotating magnetic field,
which then induces a voltage in the stator that is much large (magnetic
amplifier).

I am an EE and program power plants including turbine governors that regulate
the system frequency so I am curious about any methods that differ from what
we are doing in North America.

~~~
basicplus2
The Magnetic Amplifier is between the pilot exciter (a permanent magnet
generator) and the main exciter and sends a "feed forward" to the pilot oil
governer so it reacts before the speed of the turbo alternator slows.

------
oasisbob
Found a good summary of imbalance cash-out prices:
[https://www.elexon.co.uk/wp-
content/uploads/2016/10/Imbalanc...](https://www.elexon.co.uk/wp-
content/uploads/2016/10/Imbalance_Pricing_guidance_v11.0.pdf)

The basics seems simple enough - the system was long (too much supply) during
this period above and beyond what is contractually ordered between generators
and electricity suppliers (eg, to consumers).

Having a negative price would seem to make sense if your goal is to keep
consumption balanced with generation on an open market.

------
kristianp
Does that also mean that the producers of the excess energy are charged for
supplying power due to the negative price?

~~~
remus
Theoretically yes, though I guess the details are a little more complicated
(depending on who exactly bought the energy and under what terms). e.g. energy
company x might have bought all the capacity from wind farm y for the next 10
years, so then the fact that it's producing excess energy at that point in
time becomes x's problem rather than y's. Presumably x would factor stuff like
this in to their purchasing decision, so as long as the average price remains
above some level they will still make a profit.

------
msoad
Bitcoin mining will be super profitable then!

~~~
pavement
Or bitcoins will simply be devalued, and lose buying power until electrical
demand changes or all of the last possible bitcoins are finally mined into
existence.

------
joshribakoff
So if you operate a windmill in your backyard while prices are negative the
power company will send you a bill? Why couldn't the power company just break
the circuit if they couldn't handle the incoming power? The windmill would
still spin but not generate any power, like a gas generator with nothing
plugged in. Seems better than sending the windmill operator a bill so the
power company can generate a bunch of steam 100s of miles away...

~~~
ars
Sigh. This gets posted so many times.

There are no negative prices.

Here's how it works: Generators put out bids for how much they can produce and
the price. Consumers pull in the bids ordered by price until they have enough
power.

After that they pay everyone the _highest_ price for the power.

So making your power negative just means you want to be first on the list.

You don't actually get paid negative money. It's just a tactic.

~~~
snowwindwaves
If demand is low then the highest price can be negative.

When prices are negative Generators have to pay for the power they produced,
for the privilege of not shutting down their process be it nuclear, coal etc.
presumably hydro and natural gas would shut down in response to negative
prices.

~~~
ars
This doesn't happen. If you shut down every fast responding power source, then
there is not enough power and the price will not go negative.

For example the article talks about wind. Wind generators have no problem
shutting down.

No, it's not about the privilege of not shutting down, it's what I said: it's
simply the bottom of the order book, not the actual flow of money.

~~~
snowwindwaves
The article is about this just happening in the UK. For 5 consecutive hours
the price was minus $25.

It also happens in Ontario, and maybe elsewhere but I don't know as much about
how other markets deal with oversupply.

Wind generators generally have fixed price contracts for as much as they can
produce so they carry on generating even if the price is negative and they get
the same positive price. Or if they do have to shut down for system
reliability they will get paid even though they didn't generate any power.
That is called being constrained off.

If the price is negative it is because generators would rather pay than go
offline. The nuclear plants in Ontario will bid negative because they have
real costs if they have to alter their output.

I maintain that the price is negative because the highest selected bid was
negative, and any generators producing during those 5 hours had to pay $25 for
every MWH they produced.

are you in the power business in the UK?

I used to work on software that implemented the market settlement rules in
Ontario in order to calculate a distribution utility's cost of power every
day, and I've also spoken at length with an economist who wrote market rules,
and examined the behavior of the market participants for compliance with the
rules, but it is possible that the uk and Ontario markets differ in this
regard, although the article indicates the price was negative.

------
throwaway7645
Negative LMP prices happen all the time in the US in regions with heavy wind.
This isn't unusual.

------
watmough
"Find me a giant resistor!"

I'm sure this is probably like gas pipelines in that a swing producer can get
an advantageous contract if they agree to take or make power as needed.

------
unknownsavage
I don't understand how negative power prices can exist? Why wouldn't everyone
just dump the power into the ground and make a profit? Surely 0 has to be a
floor.

~~~
remus
You could think of the problem in reverse: there's an excess of energy and
they need to pay people to get rid of it (because using that much energy isn't
as easy as dumping it in the ground).

If you could find a good way of getting rid of a lot of excess energy (worlds
biggest kettle?) then you could potentially make a bit of a profit! Until
someone comes along and finds something useful to do with the energy...

------
stuaxo
Tell this to EDF, they recently sent a letter warning of a price increase and
gave an example where if you have £1000 bill it will go up to £1200

------
tim333
So can I get cash back by cranking up my heating next time it happens?

------
cdelsolar
If only there were some way to store energy for future use.

