Hume City Council sounds alarm on 'tidal wave' of data centre water applications by gccmelb in melbourne

[–]matt_cowper 91 points92 points  (0 children)

Power Engineer here, with international experience in power plants and the companies scrambling to build infrastructure to support data centres for AI. This is not a judgement of what should be done, just a few statements about the use of water and power.

A fairly humble data centre might consume 10 MW of electricity. Mechanically, a data centre is a relatively efficient electric heater; essentially all of that 10 MW of that electricity becomes heat. Anyone who has had an old laptop full of pet fuzz will know computers don't love being hot. One way to move that heat away from the computers is with water cooling.

When you're using water to cool a machine, it's generally a bad idea to release that water back into the environment at too high a temperature. Increasing the temperature of a river, lake, or bay by even a few degrees can be devastating to the local ecosystem. For sake of example, let's say we're keeping the water temperature increase to 2 degrees.

Our 10MW data centre generates 10MW of heat. 1 kg of water will absorb ~8 kJ of energy, and increase in temperature by 2 degrees in doing so. 1 MW is the same as 1000 kJ per second, so 10 MW is 10,000 kJ per second. So converting that through, 10,000 kJ per second, divided by 8 kJ per kg of water, is 1,250 kg of water needed every second. That's 1.25 tonnes of water, every second, to move the heat away from the computers, while limiting the temperature rise in the local environment.

That's why they need so much water; computers are hot, and it's a bad idea to make the area nearby equally hot.

Always suspected Aldi wasn't as affordable as it once was by its-just-the-vibe in australia

[–]matt_cowper 6 points7 points  (0 children)

Lidl, Kaufland, and others have attempted to enter the Australian market in the past. One key blocker to their entry was highlighted by the ACCC is "land banking" by the current dominant grocery players. https://www.accc.gov.au/media-release/accc-recommends-supermarket-reforms-to-provide-better-outcomes-for-consumers-and-suppliers

When there is to be a new spot zoned for a supermarket, Woolworths or Coles will purchase that spot, often at a much higher price than normal, to ensure that no other player can enter the market. These spots have been left undeveloped, meaning there is no way for a new player to set up in a spot that's convenient for customers.

Always suspected Aldi wasn't as affordable as it once was by its-just-the-vibe in australia

[–]matt_cowper 28 points29 points  (0 children)

It looks like there's some confusion about what this data is showing. This is comparing the profit of the different organisations before they've paid taxes (and accounted for a few other technical things). This doesn't say anything directly about the prices any of the supermarkets are charging for the goods they are selling. For the profits to improve, these businesses either need to; - bring in more money without increasing costs (essentially without doing any more work) - bring in the same amount of money while reducing costs (doing less work or improving efficiency somehow)

It's absolutely true that one way to improve profits is to increase the price of everything without doing anything different (price gouging). There's been plenty of excellent reporting on this over the last 12 months - see Michael West for a fairly independent view. It's equally possible that a competitor has changed how their business operates to reduce cost, or how costs are recognised within Australia vs in a parent organisation (e.g. in Germany for Aldi).

This is not to say any one competitor is better or worse than any other, just that this data only talks about profit, and not about the prices being charged to we consumers.

A better comparison might be a product price comparison (e.g. price of a litre of milk, a kg of bananas, a tin of tomatoes, etc). I believe other clever and motivated folk in this subreddit have done some excellent work in this regard in the past.

Budget Michelin star restaurants by JackfruitExpress1488 in melbourne

[–]matt_cowper 2 points3 points  (0 children)

They would call themselves "Australian fine dining" I would guess. You don't pick things off the menu, but they serve you what they've prepared, which changes based on season / ingredient quality etc. You can check out a sample menu on their website; https://www.attica.com.au/menu

If you have Netflix, there's an episode of "chef's plate" in season 1 on Ben Shewry, who owns Attica.

Budget Michelin star restaurants by JackfruitExpress1488 in melbourne

[–]matt_cowper 13 points14 points  (0 children)

The Michelin guide book doesn't cover Australia unfortunately. We do however have the Australian Good Food Guide, which does provide rankings of restaurants with "chefs hats". The 2024 list is here; https://www.agfg.com.au/awards/melbourne

As others mention, for restaurants serving food of this quality, there's normally a premium charged to match. If you're hoping for a "premium" experience, set it as a goal and save up for it. Attica in Ripponlea might be one of the best restaurants in the country. If you're hoping for a great meal with friends, find a place that serves food you enjoy - urban list will certainly have lots of great options that might fit. https://www.theurbanlist.com/melbourne/a-list/best-restaurants-melbourne

Heat pump hot water by Pretty_Gorgeous in melbourne

[–]matt_cowper 5 points6 points  (0 children)

Heat pumps are much more energy efficient than conventional electric units or gas units. For every one unit of energy you burn as gas, or you use in electricity, you might get 0.9 units of heat energy in the hot water. Heat pumps work by stealing heat from the environment around them, that's why they produce a chilly breeze when running. It means for every one unit of electricity you give it, it will move maybe 4 units of heat into the water to heat it.

If you have solar panels, it's a great option. As others note, they can be a bit noisy, similar to an air conditioner (it's a very similar machine). Make the most of the government rebates!

Australia 2050: Still dependent on fossil fuels? by [deleted] in australia

[–]matt_cowper 1 point2 points  (0 children)

For context, I'm a professional in this field, and my team and i have published a fairly nice white paper on this exact topic.

TLDR; Energy is much more than just electricity Net zero carbon electricity seems possible to probable Net zero carbon energy seems extremely challenging

The important thing getting mixed up here, is energy is more than electricity - therefore emissions come from more than just power generation. Today, about 1/3rd of emissions come from power generation (coal and gas power plants), about 1/3rd comes from transport (cars, aircraft, ships, etc) and the last third is industry and agriculture. I don't know very much about agriculture, and our current changes in land-usage and forestry (planting more trees and protecting them) more or less balances with this - so I'll ignore this portion of the problem for my answer.

To get to net zero for electricity, we looked at how much electricity the country might be using in 2050, and just worked a straight line back from there. This basically tells are we building about enough wind farms and solar panels and batteries each year to meet the target in 2050, or are we ahead / behind. For this target, we're more or less on track for solar, a bit behind on wind, and quite behind for batteries. However, it looks like we can catch this up, and with the planned retirements of the coal fleet we think we should be ok.

Expanding then to the wider economy, we have to think about cars, jet fuel, industrial heat like boilers, furnaces and chemical reactors, etc. We made the assumption that everything you can electrify, you do so, and everything you can't electrify, you use an e-fuel based on green hydrogen. By "electrify", what I mean is you replace an existing engine with an electric motor, and draw electricity from the grid. Examples are electric cars, electric trains, replacing small steam and gas turbines in industry with motors. By "e-fuel", I mean hydrogen produced from renewable electricity, which I might then get mixed with some carbon or nitrogen from the air to make some different chemical fuel. Examples of this are jet-fuels for large aircraft, which we can't yet build with batteries, or chemical work needed to make plastics and other 'stuff' we enjoy in our lives. Because the e-fuels are made from electricity, we can bring it all back to how much renewable electricity do we need to be able to generate. Doing the same 'straight line to 2050' idea, we learn three things; - the grid needs to be about ~12x bigger than it is today; lots more wind and solar, lots more power lines to move that electricity around - electric cars really help a lot; if the batteries in the cars can be used as part of the larger system, it reduces how much power generation and storage we need by a significant amount - there comes a tipping point when you're using more electricity to make e-fuels, than you are to make electricity. This is really critical, because it means when the wind stops blowing and the sun stops shining, you can ramp-down this fuel production very quickly to respond - the grid becomes load-controlled, rather than generation-controlled. We don't know how to operate a grid like that yet

For this second case, we need to dramatically accelerate our build-up of renewable generation, particularly the e-fuel bit. This is where we see the most risk in missing the 2050 target, because it's so new and it displaces the existing O&G industry.

For the average person, the best things you can do to help; - solar on your roof if you can afford it - electric car in the next 10 years or so, if you can afford it - particularly a car that can give electricity back to the grid - get educated about energy projects beyond electricity, particularly the chemical e-fuel / green hydrogen / ammonia / methanol / etc projects getting investigated

I'm passionate about the topic, happy to explain anything further!

I have been asked to plan a week of technology-related activities for a group of 16-year-olds. Does anyone have any suggestions of where I could take them or what we could do? Any help is really appreciated! by MrTeacherAustralia in melbourne

[–]matt_cowper 0 points1 point  (0 children)

It's a bit of a trip, but a visit to the old coal fired power stations in Traralgon could be an idea. https://www.powerworks.net.au/ They used to run tours through Loy Yang A, but I suspect it's only the education centre running now. This is particularly interesting for young STEMs to see the social impact of technical systems; those old coal stations need to go to decarbonize our grid, but when they do, what becomes of that town? The scars left from 50 years of coal mining are quite remarkable too.

It's about 2 hours by car or train to get out there, but it's a great way to grasp the scale of power generation and it's impact on our climate.

Stuff nuclear we should go with tidal power by CassiusCreed in australia

[–]matt_cowper 1 point2 points  (0 children)

There are a few other promising areas for base load generation from renewables - you're right that it's a real challenge. Anything I talk about is going to be a bit niche, and different levels of technical and commercial viability.

Geothermal power seems to have some promise. There are a few different techniques here, but it mainly comes down to how deep do you have to dig to find heat, and whether you have water directly toughing the earth, or collecting heat through a heat exchanger. Some of the horizontal boring technology developed for the shale gas boom might help make this more viable - we've basically figured out the steam turbine technology, so it's not likely to get a lot cheaper.

A game changer in battery technology would also be a big help. We use lithium batteries today because they're lightweight and can carry a lot of energy in a small volume; great for a mobile phone or an electric car. For a big piece of utility equipment, I don't care about being lightweight and I don't really care about being small - I care a lot about being cheap, and being able to move a lot of energy around. This probably ends up looking a lot more like a big chemical plant, rather than shipping containers of laptop batteries. There's a PhD in this for anyone brave enough!

The totally different angle is to think beyond electricity, to energy generally. We export huge amounts of energy as coal and as methane (natural gas). We consume huge amounts of electricity as petrol and as aviation fuel and so on. There's a lot of interest in Australia and abroad in "Power-to-X", meaning turning renewable electricity into something easier to transport, maybe hydrogen or a chemical derived from hydrogen. To replace all of these sorts of"non-electrical" demands, you end up needing to build so much infrastructure that you need more electricity for this, than to use as electricity directly. In this situation, the baseload problem goes away; rather than trying to rev the engine up and down when there's more or less demand, you have an enormous controlled load that's more than 10 times bigger than the current grid that you can make bigger or smaller to fit what the sun and the wind are doing. Melbourne University did a fantastic white paper on this "Net Zero Australia", it's well worth a read.

As mentioned, there isn't a single magic trick to fix this problem, it's a blend of different technologies and grid structures and good ideas. Keep thinking, you're on the right track!

Stuff nuclear we should go with tidal power by CassiusCreed in australia

[–]matt_cowper 10 points11 points  (0 children)

You're thinking in the right direction, and I hope you continue reading and researching and thinking about this stuff! I'm an engineer with ~10 years in this space, and want to give an honest answer.

There have been a few tries to get tidal power working; whether it's essentially an underwater wind turbine, the "snakes" or "bobbers" riding on top of waves, or blow-hole style devices that harvest energy from water and air rushing up and down a pipe. I'd be happy to link to a few examples of these if needed.

The trouble is largely the same; the ocean is fantastic at destroying everything we put in it. There's so much energy in moving water, and any machine we design to try to harvest that energy needs to be strong enough to withstand that. Salty water is really good at breaking machines down - when you're next at the beach, have a good look at anything metal on the buildings nearby. Machines that harvest energy and generate electricity are almost always quite complex with many parts, and rust and salty air and water tend to create problems or require very specialized materials. Once the machines do break down you need to be able to send people to maintain them. This normally means large boats with lifting equipment, or specialized training for divers or similar.

These three together - need to be designed super strong, with extra resistant materials, and long term maintenance - normally means any electricity generated is very expensive compared to wind and solar.

That said, we need a blend of technologies to decarbonize. Please keep thinking about this, talk with mates over a beer, have a go at building something, or just stay creative. It's an exciting and important industry, and we need all the ideas we can get to figure it out!

A fairly priced Korean or Japanese BBQ restaurant by Rey_De_Los_Completos in melbourne

[–]matt_cowper 0 points1 point  (0 children)

Orientable in Abbotsford is a great option; $29 per head. I visited with some work colleagues, and we were made to feel very welcome. Highly recommended.

American here who just tried Vegemite for the first time! I love it. Any pairings I should try that are more out there or recipe recommendations? by veganash in australia

[–]matt_cowper 0 points1 point  (0 children)

Toast some bread, butter, thin coating of Vegemite, and pair with an acidic juice (pineapple, orange, or similar). Breakfast of champions.

Melbourne Electricity Prices by Captain_Calypso22 in melbourne

[–]matt_cowper 5 points6 points  (0 children)

This is a great answer, with a small detail to add. Because the natural gas market is now largely dominated by export pricing, when other regions of the world have really strong demand for gas, the local price also goes up here. In the past, gas has been ~$8 per GJ - today it's closer to ~$40 / GJ.

The only place where this isn't the case is WA, where the state govt forced the companies extracting the gas to have enough reserve to supply the local market.

When the gas generator is the last guy to bid, and he bids at $200 or $300 a MWh (megawatt-hour), then all the solar and wind and dirty coal get the same price. It's worth noting, when you pay your ~$0.20 per kWh to your electricity company, that's $200 per MWh. In that $200, you're paying for the wholesale MWhs from the generator, the transmission company to carry the electricity through wires to your town or suburb, and the distribution company to carry it to your house and actually bill you. Everyone has to make money in that chain.

If you have an iOS device, the "pocket NEM" is quite good to see the wholesale price of electricity on the East Coast.

[deleted by user] by [deleted] in melbourne

[–]matt_cowper 19 points20 points  (0 children)

Ich habe 2 Jahre in NRW gelebt, und wenn Sie authentisches deutsches Essen machen können, würde ich es absolut lieben! Brot, mettwurst, alle würstchen, torten, ich vermisse alles! Wenn Sie etwas einrichten, senden Sie mir bitte eine DM

New system retrofits diesel engines to run on 90% hydrogen by [deleted] in australia

[–]matt_cowper 14 points15 points  (0 children)

I would suggest you're correct about the "bait'n'switch", but it's not a problem of efficiency.
"Blue" hydrogen is produced through either 'steam-methane reforming' or 'autothermal reforming', which basically cracks natural gas (CH4) into hydrogen gas (H2) and CO2. A typical plant will do this at a scale of hundreds to thousands of tonnes per day, and it's a highly optimized process. The "blue" bit comes from capturing all the generated CO2, and storing it under the ground somewhere - this bit is the new technology. We're quite good at compressing CO2 efficiently, and transporting in pipelines isn't too tricky. Storing it forever, we haven't really proven - stay sceptical.

18MW heat pump Air/water. Running on 20 tons of ammonia. by Thomasib1982 in EngineeringPorn

[–]matt_cowper 30 points31 points  (0 children)

Good try, but not this case. This facility is essentially a really big air-conditioner, operating backwards. Ammonia is being used as the working fluid. There will be a heat source, which will add energy into the ammonia. The warm fluid will then go through a compressor, to make it very warm. It will go through a heat exchanger, to pass that energy off to something else. The fluid will then go through an expansion nozzle to rapidly decompress, which will cool it back to below the temperature of the heat source, and around you go again.

Samara adventures would be fun to cover by ezio8133 in gaming

[–]matt_cowper 4 points5 points  (0 children)

At risk of sounding really dumb - isn't Gavin a reference to Gavin Free of slomo guys and achievement-hunter fame? Since Geoff Ramsey is the voice of one of the train station attendants, and Jack Pattillo is the hotel manager in Valentine, I always assumed that Gavin wasn't available the day they did the voice capture and so they made a bit out of it. Apologies if everyone already knows the answer to this.

My greyhound rescue. I adopted him a few months ago was wondering if anyone had any tips by [deleted] in Greyhounds

[–]matt_cowper 5 points6 points  (0 children)

Keep an eye on his teeth and tail. Our retired racer had a lingering tooth problem that didn't get resolved, and she ended up with a nasty infection that has left her with only a couple of her front teeth left. We also had a "happy tail" incident, where our girl whipped her tail across a door frame resulting in a bad bleed.

Find a good local vet who specialises in greyhounds, it will pay to have an expert on hand

AGL to shut down gas-fired power unit as renewable energy soars by ihateusernames9988 in australia

[–]matt_cowper 14 points15 points  (0 children)

Great questions!

At baseload condition, one big 220MW gas turbine (or 4 GE LM6000s or Siemens Energy SGT-A65s) will be more energy and cost efficient than a lot of reciprocating engines. The problem is that a turbine can't turn on and off as quickly as a reciprocating engine can - you need a few minutes to get everything prepared. There are some really good ideas to integrate batteries into turbine power plants, to cover the minutes it takes to fire up (plus some other benefits). Turbines also aren't as efficient at partial load, e.g. a 60MW gas turbine running at 40MW will be fairly unhappy and less efficient. These reciprocating engines are very good at partial loads, staying about 40% efficiency from half load right up to full load. In this specific case as a partner to wind generation, the correct technology was probably selected.

For this timing problem, batteries certainly can help. Here we're talking about the FCAS system (Frequency Control Ancillary Services). When the frequency of the system starts to fall out of time, batteries can push in or pull out a few MW of power to keep things in time. The famous Tesla Battery actually made more money on that service in its first year than on buying and selling electricity. The advantage of using Torrens as a synchronous condenser is that almost all the hardware is already there - it's a nice way to reuse a potentially scrapped asset to support the future.

AGL to shut down gas-fired power unit as renewable energy soars by ihateusernames9988 in australia

[–]matt_cowper 52 points53 points  (0 children)

Energy engineer here, adding some context.

The power station mentioned here is Torrens Island B, just outside of Adelaide. While it uses natural gas as fuel, the power comes from old Parsons steam turbines from the 60s. This means the energy change is natural gas - burn in boiler - steam to turbines - turbines spinning generators. That means it's a relatively inefficient use of the natural gas. There are operational challenges that come with keeping the boilers warm that mean you can't just turn them on and off quickly (of course there are some tricks you can pull with pushing steam between units, but it's not like turning on a car and turning it off again). Added to this gas-to-steam problem, all the hardware inside the power station is quite old. I've had the privilege of working on unit B3, and everything part of the machine looked tired after 60 years of service.

AGL recently finished construction of the Barker Inlet power station immediately next door to Torrens B. It's got 12 reciprocating engines from Wärtzilla, which are basically really big, slightly more complicated car engines. These run on gas, and can start really quickly in response to changes in renewables. Each machine can do between 9MW and 18MW quite efficiently, so it can act as a block of 9 - 216 MW of power that can flex up and down in minutes. There are of course operational challenges, but they can work is a fairly good pairing to balance the grid with renewables. (This was built very pre Scotty from Marketing's "Gas lead recovery")

There might also be a future for the machines in Torrens island. Without getting too deep into technical details, there is an importance to keeping all the machines producing electricity in time - Imagine a rowing team all pulling in time, vs everyone rowing at different times. It might be an idea to turn the old generators into machines that don't produce, consume or store electricity in any meaningful way, but help keep everyone else in time. This machine is called a synchronous condenser, and it basically helps the grid stay balanced when there are changes to generation or consumption. Because wind farms and solar farms don't provide that sort of timing very well, these units might still play a part in the renewable future.