Hacker News new | past | comments | ask | show | jobs | submit login
Portugal electricity generation temporarily reaches 100% renewable (reneweconomy.com.au)
235 points by mgdo on Apr 10, 2018 | hide | past | web | favorite | 84 comments



I see a number of people in this thread include biodiesel and wood burning with other renewable energy sources. While in theory biodiesel and wood burning are carbon neutral, the way they are used in Europe is anything but!

I wanted to warn you all that many countries in the EU currently enforce renewable resource quotas. This is what you want, however the incentives are incorrect, and the quotas are met by importing the wood/diesel from somewhere else. The EU does not oversee the reforestation/replanting of the combustible matter that is burned. So there's no guarantee that the wood/biodiesel consumed is actually carbon neutral. For all I know we're burning forests down but not planting them back. Not to mention that the biodiesel is competing with human food...


You should read about the Ash-for-Cash scandal in Northern Ireland. It was a scheme to get people using renewables for heat but the end result was some people wasting vast amounts of energy heating empty sheds to make a profit... a little like crypto-mining in a way..

https://www.belfasttelegraph.co.uk/news/northern-ireland/far...

edit: If they just had proper checks and balances and worked out the reward correctly it could have worked.


Having both a renewable and sustainable sourcing of biofuels is important, and EU actors have a obligation to the world to improve.

That said, SCHiM's statements makes it sound like the EU is currently burning the world for the sake of their own green conscience. That's not the full picture. Admittedly when it comes to import of biofuels it appears to be hard to verify and enforce that the source is renewable and sustainable. And the EU probably isn't doing much better than anyone else in that area.

On the other hand: EU:s primary source of biofuel is internal production and not imports[0] and there is little deforestation going on in the EU, many European countries even have a slight net positive reforestation[3], despite a huge internal production of biofuels.

[0] https://hub.globalccsinstitute.com/publications/renewable-en... [1] https://en.wikipedia.org/wiki/Deforestation_by_region [2] https://rainforests.mongabay.com/deforestation/

There is also a great interest in increasing the capacity for local sourcing of biofuels to reduce dependency of imports and creating jobs locally. So while there is reason to be mindful of how biofuels are sourced, and that there still are bad actors in the EU (as well as and elsewhere), my impression is that the general trend in the EU is one of increased awareness and positive development.


Seems to me that the more the topic is researched, the worse it looks for large-scale usage of biomass for energy. Biodiversity loss, nutrient loss from intensive cultivation, long timescales often involved in "carbon neutrality", massive emissions due to land use changes (e.g. draining a swamp to plant a forest), etc. etc. Add in the fact that biomass is probably the worst form of energy we have in terms of W/m^2.

Basically, AFAICT calls for large-scale biomass energy usage tend to be greenwashing scams where the real motivation is rural politicians who want short-term $$$ for their constituents, damn the long-term consequences.


Currently we are passing through an atypical wind and rain period. Our dams are full and pouring out water as we are producing more energy than we consume.

Despite all of this energy prices don't drop as they are bound to one of the few legal monopolies in Europe: the grid operation cartel (REN in the article, there is only one allowed for each EU country).

Also this feels as fake news since we have a few very old (and historically insecure, like sines power plant and carregado power plant) fossil fuel power plants that are still operating with no signs of slowing down while making profits through several scams in chemical engineering their way into the 0 emissions lot.


Sines is the only coal plant in the country. Carregado has been converted to a combined cycle natural gas plant. The remaining thermal power plants all burn natural gas/biomass.


Thanks, i edited my comment accordingly :)


Empirically, these high energy prices seem good: it leads to less energy waste and allow investment in more expensive but cleaner energy sources.

However if energy prices rise too much it can hurt quality of life: e.g. home heating/cooling in Portugal is, at most, spartan.


are batteries (or some sort of storage) in the infrastructure plan for the future?


Hemp supercapacitors might be a good solution to the energy grid storage problem. Hemp absorbs carbon, doesn't leave unplowable roots in the fields, returns up to 70% of nutrients to the soil, and grows quickly just about anywhere.

Hemp bast fiber is normally waste. Hemp anodes for supercapacitors are made from the bast fiber that is normally waste.

Graphene is very useful; but industrial production of graphene is dangerous because lungs and blood-brain barrier.

Hemp is an alternative to graphene for modern supercapacitors (which now have much greater power density in wH/kg)

"Hemp Carbon Makes Supercapacitors Superfast” https://www.asme.org/engineering-topics/articles/energy/hemp...

> “Our device’s electrochemical performance is on par with or better than graphene-based devices,” Mitlin says. “The key advantage is that our electrodes are made from biowaste using a simple process, and therefore, are much cheaper than graphene.”

> Graphene is, however, expensive to manufacture, costing as much as $2,000 per gram. [...] developed a process for converting fibrous hemp waste into a unique graphene-like nanomaterial that outperforms graphene. What’s more, it can be manufactured for less than $500 per ton.

> Hemp fiber waste was pressure-cooked (hydrothermal synthesis) at 180 °C for 24 hours. The resulting carbonized material was treated with potassium hydroxide and then heated to temperatures as high as 800 °C, resulting in the formation of uniquely structured nanosheets. Testing of this material revealed that it discharged 49 kW of power per kg of material—nearly triple what standard commercial electrodes supply, 17 kW/kg.

https://scholar.google.com/scholar?hl=en&q=hemp+supercapacit...

https://en.wikipedia.org/wiki/Supercapacitor

I feel like a broken record mentioning this again and again.


If you're going to be mentioning this again in the future please correct your usage of power/energy density. Power density is measured in W/kg, energy density is measured in Wh/kg. Supercapacitors tend to excel in the former but be poor in the latter. You mentioned power density but used units for energy density. This happens so often in media that I feel the need to correct it even in a comment.


> please correct your usage of power/energy density. Power density is measured in W/kg, energy density is measured in Wh/kg. Supercapacitors tend to excel in the former but be poor in the latter.

I'd update the units; good call. You may have that confused? Traditional supercapacitors have had lower power density and faster charging/discharging. Graphene and hemp somewhat change the game, AFAIU.

It makes sense to put supercapacitors in front of the battery banks because they last so many cycles and because they charge and discharge so quickly (a very helpful capability for handling spiky wind and solar loads).


I think you may still be a little confused. Power density is the rate at which energy can be added to or drawn from the the cell per unit mass. So faster charging and discharging means high power density. Energy density is the total amount of energy that can be stored per unit mass. Supercapacitors are typically higher in power density and lower in energy density than batteries[1].

You're right that it makes sense to put supercapacitors in front of the battery banks for the reasons you said.

[1] http://berc.berkeley.edu/storage-wars-batteries-vs-supercapa...


I must have logically assumed that rate of charge and discharge include time (hours) in the unit: Wh/kg.

My understanding is that there's usually a curve over time t that represents the charging rate from empty through full.

[edit]

"C rate"

Battery_(electricity)#C_rate https://en.wikipedia.org/wiki/Battery_(electricity)#C_rate

Battery_charger#C-rates https://en.wikipedia.org/wiki/Battery_charger#C-rates

> Charge and discharge rates are often denoted as C or C-rate, which is a measure of the rate at which a battery is charged or discharged relative to its capacity. As such the C-rate is defined as the charge or discharge current divided by the battery's capacity to store an electrical charge. While rarely stated explicitly, the unit of the C-rate is [h^−1], equivalent to stating the battery's capacity to store an electrical charge in unit hour times current in the same unit as the charge or discharge current.


It does sound amazing and economical, like almost too good to be true, but I very much hope it is true. What are the downsides? Is there a degradation problem or something similar? Other than the stoner connection in people's minds, what kind of resistance is there to this? Why isn't it widely known?


You know, I'm not sure. This article is from a few years ago now and there's not much uptake.

It may be that most people dismiss supercapacitors based on the stats for legacy (pre-graphene/pre-hemp) supercapacitors: large but quick and long-lasting.

It may be that hemp is taxed at up to 90% because it's a controlled substance in the US (but not in Europe, Canada, or China; where we must import shelled hemp seeds from). A historical accident?


They have dams!

Given the over provisioning required to be able to ensure a battery will be able to provide a guaranteed amount of energy, such as last say overnight in 5 years, and that batteries are good for a fixed number of cycles after which they have to be replaced, batteries were not competitive with pumped storage and all the civil works that entails on a project currently under construction.


Correct. All of the large dams have been retrofitted with pumps. This involves creating the structures for pooling water downstream so you can pump it back up should the need arise.

Dams have many problems. They can only be built on certain topographies, they have an ecological impact (destroy an ecosystem, albeit creating a different one), and have a social impact. However, in the context of energy production, they are amazing. They can start and stop as fast as loaded thermal plants (without the readiness fuel consumption cost), they are 100% renewable, provide aquifers for collecting urban water and provide the best energy storage/temporal load balancing technology today.


Portugal’s gas and electricity the most expensive in Europe

https://algarvedailynews.com/news/8958-portugal-s-gas-and-el...

Portuguese with highest standardized energy bills in the EU http://www.theportugalnews.com/news/portuguese-with-highest-...


"That shows how ridiculous a 27% target for 2030 is" Yeah well, if your country has plenty of wind coming from the ocean and you are not a big industrial nation with a lot of energy demand, then 27% seems to be a low goal...


These statements are utterly infuriating. Yeah Iceland has been 100% RE for years, guess what when your country can do 40MWh/person/year on hydro alone and isn't even at 100% hydro capacity yet it kinda fucking helps.


> 40MWh/person/year of hydro

That can’t be right....

<Google...google...google>

Well shit.


Having an overall, average goal for the whole EU kind of implies that some countries that can will contribute more than those that can't. What's the problem?


The problem with that average probably is that the countries for which it's more difficult to reach these goals usually are also those countries that account for most of the energy consumption.

If Portugal reaches 27% of energy consumption from renewable sources that's not nearly as significant in terms of absolute energy consumption than when say France or Germany reaches that goal.

Both of these countries don't have a lot of naturally occurring phenomena or places that lend themselves to hydroelectric or geothermal energy production. So, they have to resort to ways that work everywhere but are comparatively more expensive or difficult to implement.

So, while countries like Portugal or Iceland reaching such goals certainly is commendable the 'battle' will be won elsewhere.


Yeah, poor Germany, producing only 40 terawatt-hours per year using solar and 90 using wind: https://energytransition.org/wp-content/uploads/2018/04/non-...


Not sure why you get downvoted for that. Germany's carbon emissions are higher than most neighbours because of the excessive use of coal, but renewables are already above 27% of demand and growing.


That is brilliant. Right now, Portugal is getting 14% of its electricity from gas and 8% from coal. But then it is also exporting 19% to Spain so it is very close to being completely renewable.

https://www.electricitymap.org/?page=country&solar=false&rem...


The complete history is that we had a drought in the Iberian Peninsula that made electricity cost skyrocket last year.

Now last two months we had an abnormal rain season with lots of snow and rain, so dams and water reservoirs are getting more water, and rivers Tagus and Duero-Douro could carry more water to Portugal as the dams upstream are getting full, like it should for this time of the year.

The complete history is that in the Iberian Peninsula there are three months with almost no rain: June-July and August because of the Azores high and you can not depend on hydro generation there.


Hydro generation can happen even without rain, that's what reservoirs are for. The problem is if this drought extends beyond that, as it did last year.


The article omits the fact that as a consequence Portugal has one of the highest energy prices in europe and that fact played a significant role in the portuguese economic crisis that started back in 2008 and culminated in the 2011 banktuptcy and subsequent bailout program.


>The article omits the fact that as a consequence Portugal has one of the highest energy prices in europe

It's in the Top 6, yet only slightly more then Euro-area average. [0]

Though it might be higher if you take average income into account.

[0] http://ec.europa.eu/eurostat/statistics-explained/images/7/7...

from http://ec.europa.eu/eurostat/statistics-explained/index.php/...


But you would have to adjust for cost of living right? Electricity bills can easily go over 200euro for a family of 3 in the winter, median wage is probably around 1k...


Before taxes it's even below EU average.


Which doesn't matter because you have to pay taxes.


It matters if you want to judge whether renewable energy makes production more expensive or not.


You're missing the point. The portuguese state levies energy taxes as part of the public-private partnership deals which subsidize corporations that took a part of the national renewable energy program.

Those taxes are so eggregious that even the IMF demanded that the portuguese government should lower them as they harmed the economic recovery.


The energy prices are not completely tied to this investment. Most of it came from EU funding.

Most of the price is taxes of various kinds and monopolistic behaviour by EDP. After the privatization, but increasingly so after being sold to the Chinese state.

The market is only nominally free, and since REN who owns the network is ALSO owned by the Chinese state (who the hell thought that was a good idea? Oh, he is the Chairman of EDP now), that won't change.


> The energy prices are not completely tied to this investment. Most of it came from EU funding.

Minor nitpick: Most of it predates the EU. It came from national effort first, and the Marshall Plan next, from the 1930s to the late 60s. That's when most dams were built.


> portuguese economic crisis that started back in 2008

Global economic crisis.


Might have started globally, but we did our share to "improve" it with our housing credits and the way many business work.


As a consequence of what? Of them subsidising fossil fuel?


Mostly as a consequence of a mismanaged monopoly held by EDP. Regulation didn't work, and we made it worse during the crisis by selling all of EDP (including REN, the electricity transport company) to private foreign entities. I don't see any hope of a more efficient market in the near future.

Not everything is poor management, though. The current infrastructure, which allows these records, is the result of a huge hydro-dam program in the 1950s and a very strong incentive for wind power in the noughties.


> that fact played a significant role in the portuguese economic crisis

Citation needed, or stop spreading disinformation


On the one hand this is great news. On the other, (hydroelectric) dams appear to me to be very invasive, with high costs for the environments and the populations around them.


They are but a lot of the old dams, fallen into disuse long ago are being removed. A few new big ones are a nuisance but there's thousands upon thousands that hinder small rivers

Here's a map, though nothing on Portugal, the Spanish map is quite impressive

https://damremoval.eu


Amazing resource, thank you. To quote[0] on the environmental impacts alone:

- Dams impact every aspect of healthy rivers.

- Dams lead to loss of river habitat as the river is transferred into impoundments, (impoundments or reservoirs are not lakes).

- Dams lead to loss of river habitat as the hydro and sediments dynamics in the river are severely modified. This impact can reach hundreds of kilometres down the river and affect deltas.

- Dams seriously impede the migrations of fish and this leads directly to the decline and even local extinction of many species. If we want to keep certain fish species in Europe, like eel, sturgeon, salmon, it is of great importance to restore connectivity from sea to source. However, we tend to focus on fish in relation to dam impacts; but many other species living in the water and on land depend on natural rivers and would benefit from free- flowing rivers.

- Modification of water dynamics do also alter habitats and thereby favouring different, often invasive species

[0]: https://damremoval.eu/about/


Yes. In fact, the biggest dam in Portugal (Alqueva) has probably had a negative impact on multiple species of land carnivores, including endangered species like the Iberian lynx, due to its large extension of flooded land.


Damned if you do, damned if you don't? Pun intended.


Yeah, hydro should really not be considered renewable, not just because it's invasive, but also because it's not renewable: dams fill up with silt and have to be either abandoned, removed or desilted.

Go read Cadillac Desert, it's been written a few decades ago, but it's a real eye opener on the history of water management in the (west) US.


> but also because it's not renewable: dams fill up with silt and have to be either abandoned, removed or desilted

If you consider wear and tear on the infrastructure, then nothing is renewable. Wind turbines don't last forever, solar panels slowly produce less power, etc.


Yeah but there are only so many places where you can build a dam. And also the usual equation renewable = safe for the environment and humans doesn't quite work: as many other commenters have pointed out dams are very bad for the environment, and they sometimes kill a bunch of people too.

https://en.wikipedia.org/wiki/Vajont_Dam


Calling a dam destructive to the environment is way too loaded. Dams do destroy ecosystems, but they create new ones. It's not like they tear down tropical forest to build a parking lot.

If the destruction affects endangered species, I may land on the no-dam side. Otherwise, it's a preference question. Do you prefer changing an healthy ecosystem into another healthy ecosystem or do you prefer building a thermal/nuclear power plant? I prefer the renewable one.


>temporarily reaches

And that's a problem. You don't want "temporarily". If it is temporarily then it is if it doesn't exist at all - there has to be a prepared reserve (read power plants operating) for the cases when renewable doesn't reach 100%.

AFAIK, energy distributors have to have the equal amount of production capacity in regular power plants as there is renewable energy (well, not renewable but wind+solar - the ones that variate the most).

Until battery packs become widely available, I would say that solar+wind is quite a poor choice to reduce CO2 (assuming that it is the reason why we do renewable at all).


If you read the article, you will see that 55% of the power in question was hydro, so your comment seems a little beside the point, since we are not talking about wind+solar, but wind+solar+hydro.

Though obviously it's spring so this isn't a year-round possibility.


> ends fossil fuel subsidies

With much teeth grinding from companies that sold all its production to the network, and then bought the energy they needed at lower price. The subsidies did their job, the installed capacity is now large enough.


From what I can tell, they weren't ended, just suspended pending the reply of the EU about whether they don't break the rules regarding public financing of the energy sector.

Source (Portuguese): https://dre.pt/web/guest/home/-/dre/114949214/details/maximi...


This is great news. I'm especially happy to see fossil fuel subsidies disappear as well. Energy sources should compete based on efficiency, and efficiency gets mangled by interference on cost of goods. Renewables will dominate soon as cost of production beats out fossils, and this is a great thing for our wallets and our planet.


>The group noted that while fossil fuel plants still worked for short periods to complement the electricity supply, those were fully compensated by other periods of greater renewable production.

Portugal produced enough renewable energy in a month to cover their electrical demand for that month if the demand had been at convenient times. They also produced energy in non-renewable ways to meet short-term electrical demand within that month.


Scotland managed it from wind alone.

"On one day in particular, 15 May, output from turbines generated enough electricity to power 190% of homes or 99% of Scotland's total electricity demand."

http://www.bbc.co.uk/news/uk-scotland-40149604


Let’s hope more EU countries follow the path


Unfortunately the problem with renewables is that they work well only in countries with a specific climate. For example in Poland, none of the renewables are really worth it as much as it is in other countries. We don't have enough sunny days to make solar great, we don't have enough strong winds to make wind farms great and we don't have enough rivers to make hydro plants great :(


> We don't have enough sunny days to make solar great

That's what people say about Germany too, but they keep breaking surprising solar records. Looking at the maps at https://en.wikipedia.org/wiki/Solar_power_in_Germany#/media/... and https://en.wikipedia.org/wiki/Solar_power_in_Poland#/media/F... it looks like the potential is not that different, though Southern Germany does have some areas with more peak sun. But those are not the only areas where they have solar installations in Germany.

EDIT: Let me qualify this a bit, the colors are somewhat misleading in direct comparison. Looking at the numbers, most of Poland seems to be roughly comparable to the northern half of Germany in terms of solar potential. And that potential is used in Germany, even in the north.

> we don't have enough strong winds

I'm really just guessing here, but my impression was that having access to the sea basically guarantees offshore wind power potential. Also, all of Eastern Europe is basically a single flat pancake, you should get strong wind straight from Russia, I think. That was the case when I was living in Eastern Austria, at least (where there is a bunch of wind power).


There has been a lot of misinformation about this unfortunately(which ultimately enabled the current legislation). GP appears to have fallen prey to this as well.

The facts are as follows:

- We have an adequate amount of sunny days as shown by this system: http://www.tinyurl.com/Chotomow-dom (annual yield above 1MWh per peak kW).

- The conditions for wind power are favorable https://www.gmina-izbica.pl/images/articles/wiatr-predkosci.... (shown on the map: 10-minute average wind speed at 10 meters above ground level).


> Also, all of Eastern Europe is basically a single flat pancake...

Only after the north of the Danube.


all of Eastern Europe is basically a single flat pancake

The steppe, it’s called. But don’t forget the Urals.


Which are in Russia


... so will affect winds coming from Russia


I think it's more a combination of very real cost problems and unstable Polish politics of the moment. The wind is there, but the government has started reneging on its agreements. https://www.ft.com/content/a26dda50-af3b-11e7-aab9-abaa44b1e...


Seems like there's plenty of wind activity in the baltic. Couldn't you create off-shore wind farms like Denmark does?


Good thing there's a multi-country grid. It could be windy in one country, tidal in another, sunny in another, water stocks high for hydro elsewhere.


Sea access should do...

But really, why would you only invest in renewable energy at home.

We should be building a solid grid and just hook up sun farms and wind turbines where we get the best return on investment.

Relying my hydro from Norway to cover days with little wind should work fine.

Note: you won't want to have wind turbines close by regardless, put them at sea :)


Isn't that the point of being in an Union, each one participating with what they do best and within their possibilities?

You begin to take some refugees without complaining and sunny southern european countries give you some of their solar power - deal? /s


I wish I could say the same about Spain... https://www.quora.com/Has-Spain-really-banned-private-solar-...


It's sad that they could only end the fossil fuel subsidies when they had already reached 100% renewable power.

Hopefully other countries will end fossil fuel subsidies much sooner than that.


Actually, the subsidies weren't ended, just suspended while the government waits for EU decision about whether they are in accordance to the EU directives. If the EU says they are, they will be resumed. The government does say they plan to review them, but hasn't yet.

Still, the subsidies are just to ensure that the plants are kept ready to assist if there's a need.


This is a great achievement, but the headline is misleading because it's only Portugal's ELECTRICITY GENERATION that (temporarily) reached 100% renewable, and electricity constitutes only about 25% of Portugal's energy consumption (source: Eurostat). A further 15% or so of Portgual's energy consumption is renewable in other forms (wood burning, biodiesel), but that leaves a large majority of fossil fuels (about 50% petroleum for transport and 10% natural gas for heating).


You're absolutely right that the article title is incorrect, but reaching 100% renewables including heating and transport would be a sci-fi feat at this stage so it's not really that misleading. The fact it's electrical generation is almost implied by logic. Almost.

Still, it should be corrected for clarity. But it seems a remarkable achievement.

On the fact that it's temporary, I'm curious to see how long any country or even region takes to reach 100% permanent renewable generation. That could be similarly sci-fi-ish, even if there's some recent hope in battery-related news stories.


If you have mountains, you have batteries. Pump water up the mountain when you have extra juice, pump it down when you need extra. I was also curious about a sort of spinning mass energy storage. Get a big cylinder of concrete or lead spinning with the extra juice, then generate the energy back.


You're thinking of flywheel storage. There are a few of these running. One pretty big one in Ontario for example.


Tangentially, some car manufacturers have done prototypes of this as well. Look up the Porsche GT3R Hybrid or the Volvo S60 prototype for an example... Unfortunately it appears that for one reason or another no one has decided to move forward with these into actual consumer cars.


There are a few reasons including weight, safety, cost, package size, etc. A flywheel that can hold appreciable energy requires high speed or high mass as well as a low drag / bearing friction environment. The passengers must be protected from catastrophic failure of the flywheel by some strong casing ( more weight ) and cant be 'turned off' in an emergency. In race cars where heavy braking and acceleration are the norm and cost is not a factor, light, strong, fast flywheels can do a good job provided they run on active bearings in a low pressure casing. In a heavy road car the additional weight required makes the engine less efficient in terms of mpg, and probably less safe during a crash ( or if similarly safe, much heavier due to casing requirements ). Combine this with the inability to externally charge the flywheel and there arent really any great reasons to use it over electric energy storage


There are very many people to whom it is not obvious that this only means electricity. Probably more than half the people that will see this headline, whether on HN or elsewhere. Think of all the environmental activists with no physics background who can't tell a Joule from a Watt or a Volt from an Amp. (There's nothing inherently wrong with not knowing but information should be presented so that it doesn't mislead, and people like that are probably part of the audience for the article.)


I'm sure there are a few, but you don't need a physics background, nor even to know the difference between Volts and Amps to realise that most cars on the road use petrol/gas. And that you or people you know likely pay a gas bill for your home heating.


While I don't want to take anything away from Portugal, we should maintain objectivity. The Netherlands for example have a poor rating in regards to renewable energy source.

Looking back at Portugal, their main source is a hydroelectric dam and their second is wind.

The netherlands have basically no elevation, so they literally can't make an (efficient) dam.

The Netherlands also have extremely bad ratio between landmass/population, so there's quite literally little space for mass Wind turbines.

Portugal also has the luxury of not sharing their coast, while the netherlands have to share the (small) northern sea with multiple countries (England for one) so they literally can't build wind turbines randomly in the sea without breaking a treaty.

Netherlands and England as well are not exactly sunny countries thus solar is also inherently more inefficient than countries closer to the equator.

Then there's general climate arguments (annual wind amounts and speeds)

I think these are very important factors because the variable for a coal plant is the same, so a direct comparison between Portugal and The Netherlands and potentially other eu countries is somewhat apples and oranges.




Guidelines | FAQ | Support | API | Security | Lists | Bookmarklet | Legal | Apply to YC | Contact

Search: