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Spazzle posted:You can't just use average values of solar radiation quote:If you have a couple of days where the weather deviates significantly from the average value your backup capacity will be unable to keep up. quote:You need to significantly overbuild your infrastructure to compensate. A few caveats:
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Sep 5, 2012 07:14
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the posted:Imagine if every home of the 55,000 homes in my town had solar panels on the roof? Our power demands would drop tremendously. Unless you've invested heavily in battery arrays, then your family is not going to power itself (because your generation and consumption patterns always peak at different times of day, and often in different seasons). You'll sell power onto the grid sometimes (which is a big pain in the rear end for the local utility to deal with; many of them refuse to accommodate household feed-in until forced to do so by legislators/regulators) and you'll buy it back at most other times. Suburban wind turbines are probably a non-starter. Your neighbours (and/or HOA) will bitch about visual pollution, loss of property value, noise, bird kills, EM allergies, zoning disputes, etc... And if the idea actually catches on, then the ROI/EROEI will decline as each newly-constructed windmill casts its shadow across the existing ones. You might even see neighbours suing each other, as "early adopters" seek to block new deployments (in order to safeguard their own investment). Also, most windmills have a minimum cut-in speed - they'll generate zero power until the wind exceeds a critical threshold (which is why they're built en masse in high-wind-intensity corridors, rather than being scattered about the country at the whim of homeowners). If you want to build "green households", then you should aim for the low-hanging fruit first:
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Sep 6, 2012 06:29
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Aureon posted:Another mean is needed. A few concerns have been raised in this thread (e.g. hybrid solar/biomass has not been proven on a commercial scale; biomass should not be considered a carbon-neutral energy source; it would be infeasible for most nations because they lack Australia's extremely consistent insolation). I'm wondering if you have some fundamental objection to this approach, or a reason why you think it would be unworkable in practice? Or is the biomass backup scheme irrelevant because you don't believe in the feasibility (and/or economics) of their proposed CST tech?
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Sep 9, 2012 02:46
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Narbo posted:Efficiency won't solve any energy problems alone but it's a fantastically cheap place to start. Even if we assume massive standardization/streamlining of design and regulation, there are only a few foundries in the world the world that can cast a PWR pressure vessel. In the case of CANDU-type reactors, the current global production of heavy water would be sufficient to provide for only one to two new reactors per year. Regardless of the exact reactor technology, we'd also need to ramp-up mining, fuel fabrication, and (don't forget!) training of specialized construction crews and reactor technicians.
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Sep 15, 2012 06:38
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Cartoon posted:As it effects almost all energy sources, has anyone ever calculated the effect on global warming that the energy exchange between the heated vapour and the atmosphere involves? Your point has been explored in science fiction, though. The classic novel Ringworld included a highly-advanced race whose industrial processes generated so much heat that they had to remove insolation from the equation (by moving their homeworld away from its star) lest the planet's surface become uninhabitable.
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Sep 19, 2012 07:16
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Flaky posted:Has any research been done on marrying nuclear fuel with a fuel cell type set-up instead of using steam pressure to push a big ol' turbine? This is very speculative, though, because the automotive fleet switchover would take decades and hydrogen itself is a pain-in-the-rear end to distribute. For the present, any new nuclear power plants should be used to retire coal-fired power plants.
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Sep 19, 2012 16:24
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Quantum Mechanic posted:I'm not sure what modelling you're talking about here. Weather pattern modelling? A longer-baseline model would tend to include more unusual events (e.g. loss of insolation due to volcanic haze) which would force the designers to increase the nameplate capacity of the system and/or improve their backups (conserved hydro and biomass-firing).
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Nov 14, 2012 22:37
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Flaky posted:I agree that it was extraordinary. I had never heard a claim (and it wasn't the only amazing one) like it which is why I linked the video. Even then, your summary was misleading. The $25 million pitch was the capital cost of a single new printing facility (it was also secondhand information; I tried to find a firsthand source on the University of Melbourne website but didn't get any results). Printing 25 GW of nameplate capacity (over a ten year period) would require additional money for operating costs and raw materials (probably wages also, but maybe they could get undergraduate students to work in the factory for partial course credit). 25 GW of nameplate capacity is not the same thing as 25 GW of grid-available power, since you lose a bit of output with every instance of inefficiency: suboptimal installation geometry, urban haze, dust accumulation, etc. The $25m also excludes the deployment cost. Buying a half-kilowatt worth of magic plastic at the Home Depot and slapping it on your roof and windows is awesome; wiring it up, fighting city hall for zoning and permits, waiting for the electrician to show up, installing an inverter + feed-in meter + battery array... less awesome (and also fairly expensive). You've also omitted an important caveat which was mentioned in the context of the $25m claim: Professor Mike Sandiford: "This ([thin-film Si photovoltaic]) hasn't gotten there yet. This is in the development phase. There's huge challenges in taking this sort of technology from the laboratory to the market. To scale what you can do in the laboratory through industrial-scale processing. Having the facilities to try and get that learning going is the challenge."
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Nov 21, 2012 09:10
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The headline is a bit misleading. "Unsubsidised" refers to capital costs, but Germany (on which the report is presumably focused; I can't find a copy of it online) has a feed-in tariff for household solar power. I don't like FIT programs in general because they can seriously distort the market (encouraging deployment in the least-productive areas, such as household rooftops) and then (when the over-investment becomes obvious and the FIT funding mechanism is exhausted) change abruptly. This already happened in Germany, where the "20 year guaranteed FIT rates" were slashed repeatedly between 2010 and 2012. Governments agencies are learning from these kinds of mistakes, albeit slowly. The FIT system here in Ontario was designed with quotas for each tier (household < 10 kW, industrial < 50MW, etc) so that it wouldn't be over-subscribed. Sounds reasonable, right? Applications were submitted, the most promising ones (e.g. the applicants who demonstrated sufficient credit/cashflow to actually build a solar array) were approved, and construction began at several sites. But the original intention wasn't to build solar power per se, it was to build up demand and thereby launch a domestic solar industry (including R&D, manufacturing, and export). Critics pointed out that the PV panels for the new projects were simply being imported from Texas and California, whose well-established PV firms could undersell any nascent local manufacturers. A "domestic content" proviso was added to the program, but the agency doesn't actually pre-approve suppliers/contractors as legitimate; the onus is on FIT participants to prove, if audited, that their project is at least 60% domestic (50% for wind projects). What does this mean for projects that were already underway when the rules changed? OPA has been reluctant to issue a definitive policy, preferring to take things on a case-by-case basis (after all, "regulatory ambiguity and threat of audit" is a great way to encouage investment, right?). Fake Edit: And then homeowners found out about the FIT program and were angry that their taxes/rates would provide windfall profits to politically-connected early adopters; some threatened lawsuits. There were plans to appease them by opening up a bunch of additional slots on a "lottery" basis; this plan was decried by early adopters who had run afoul of the quota limit and had seen their own applications denied. These guys also threatened legal action since they believed that they had a priority claim on any new FIT opportunities. And then the FIT rates were adjusted*, the "windfall" aspect diminished, the complaint-filled web forum was taken offline, the application process was heavily bureaucratized (to avoid the appearance of favouritism), and the hubbub (mostly) died away. *The official MicroFIT rate for rooftop PV is still quite generous (54.9c/kWh) but it does not adjust for inflation; over a 20-year FIT contract it will become steadily less valuable. The homeowner must also bear the cost of inspections, meter upgrades, supplementary insurance, etc...
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Jan 24, 2013 02:56
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Kaal posted:Interesting post GulMadred. Could you talk a bit about what the feed-in tariff is and how it interacts with the various power source options? In a perfect world, we'd decide on an ideal energy generation mix based on technology and then move towards it as economic factors allow. In the real world we can't do this because because utilities have been deregulated/privatized and 50-year plans don't mesh very well with election cycles; we can only offer incentives and hope that private firms pursue them. These incentives sometimes occur as government subsidy of capital costs for new construction (or, in the case of nuclear power, by special coverage due to the infeasibility of obtaining insurance on the open market). Capital subsidies are politically sensitive, though - if construction costs go over-budget then the Minister of Energy (or local equivalent) is going to face some heat; the government will need to commit more funds to the distressed project (scandal!), writeoff its original investment (scandal!), or try to strongarm other private firms into a takeover/rescue deal (scandal!). There's also the risk that the subsidy deal will be modified or canceled in the aftermath of each election, particularly if the recipient was a political ally of the former government. Feed-in tariffs are seen as a way around some of these problems. The government (or independent grid-operating agency) signs a contract with a private entity, agreeing to buy electricity at price <x> for a fixed term (20 years is common). Since the government pays only for energy that's actually delivered, there's much less "involvement" (and risk of scandal) with any particular firm or venture, and there's no harm to the public interest if a construction project misses its deadline. It's also hoped that succeeding governments will be less likely to rescind or modify any particular tariff agreement, since each one is a standard-issue contract rather than a sweetheart deal. The major risk (as I explained above w/r/t Germany and Ontario) is ex post facto modification of the contract terms. This may be due to political reasons (e.g. the incoming government is much less "green" than the one which signed the original solar FIT deals) or simple economics - FIT power is more expensive than the standard stuff, and honoring those contracts might be seen as a luxury during a recession or budget crisis (e.g. "Minister decides to close schools in order to maintain payouts for hippie power!"). If you're an energy provider who was depending on those favourable 20-year rates, then you might find yourself unable to repay your amortized capital costs. If FIT contracts are consistently modified or dishonoured, then it will be increasingly difficult to attract new participants. Oversubscription is another risk, as I mentioned in the previous post. It's fairly easy to manage it with simple quotas, but then you need to include anti-abuse mechanisms (because you're dealing with a private-profit scenario). For instance, the FIT program in Ontario was plagued by "sockpuppets." Officially, each individual or firm could submit only one application (which would include all of the sites and projects that they planned to develop). This was troublesome for the big enterprises - if you submit a 2500MW plan and there's only 1800MW of remaining unallocated quota, then you're certain to be rejected. If you submit a modest 1000MW plan then you may miss out on lucrative opportunities. To improve the odds, some applicants split up their plans into dozens of individual items and filed each one as a separate application through a separate shell company. The intent, of course, was that their actual "operating" company would simply acquire any shell company whose application was successful, and proceed to develop the site, generate power, and collect the FIT payouts. The reverse problem also occurred, with "squatters" filing applications and then attempting to sell the successful ones to actual operating companies. FIT contracts themselves became a sort of black-market commodity. Because of these sorts of shenanigans, under-delivery is also a problem. You can target 1000MW of new power generation, issue 1000MW worth of FIT contracts, and then find that half of the approved ventures fall apart in the planning/financing stage. So you need to either take a page from the airlines' playbook (overbook using a best-guess estimate of the rate of delivery) or hire extra staff so that you can investigate the applicants, closely monitor their progress, and promptly replace the failures with new applicants. In the case of Ontario, the power agency started collecting security-deposit fees from applicants so that they'd have a greater incentive to actually complete their projects rather than simply flaking out. In order for the program to succeed, the operating agency (and/or regulators) must understand the business. They must correctly assess the capital costs of new construction, cost of borrowing (interest rates and trends), operating and maintenance costs, availability of materials and skilled labour, etc. Inflation is another important factor; the Ontario FIT program uses different inflation-indicexing policies for the various renewable energy technologies. I don't know their rationale for doing so, but I suspect that it's a bit deceptive - they could offer a modest FIT rate which is fully indexed to inflation, but they hope to attract more participants by offering a very lucrative "introductory rate" which is not indexed at all. Trying to predict the competitive landscape over a 20-year period is very difficult, so FIT programs sometimes remove it from the equation by including a priority arrangement. That is, "the goverment/operator must buy, at any hour, as much power as <applicant> is able to generate and willing to sell, regardless of whether government/operator could buy said energy cheaper from other sources." Such clauses reduce uncertainty (thereby encouraging participation in FIT programs) but might expose the government/operator/public to greater risk. If we invented cold fusion tomorrow then we'd still have to pay for the obsolete PV power at an elevated price. Such preferential arrangements may also increase the complexity (or reduce the efficiency) of power dispatch operations - but that's beyond my ken. The exact financial arrangements (e.g. schedule of payments) depend on jurisdiction. If you're bored then you can read up on some of models that were proposed in the UK - "Fixed FIT", "Premium FIT", "FIT CfD", "Regulated Asset Base", and a few more that I can't recall. ------- Interactions with power source options FIT programs are generally intended to balance social, technological, and economic factors. For example, they'll sometimes offer a higher rate for rooftop PV than field PV - the former is technologically inferior but it encourages grassroots involvement (at the homeowner/consumer level) and thus achieves a social benefit (fostering "green" attitudes). Solar subsidies are also usually greater than wind ones, not because of any perceived difference in "virtuousness", but simply because solar requires larger subsidies to be cost-competitive in many countries (especially here in Canada - we ain't exactly equatorial). Small-scale power generation projects usually obtain richer subsidies than their large counterparts*, even when using the same tech, because the large ones are expected to benefit from superior management and economies of scale. Nuclear and fossil energy are not eligible for any FIT program that I know of. Biogas, hydro, and wind usually attract modest subsidies. They're fairly mature (don't hold your breath for any order-of-magnitude improvements in efficiency!) and have decent EROEI; market logic says that they'll expand without assistance. The FIT subsidy simply speeds things up, which is useful if you're eager to retire a set of coal-fired power plants that you promised to get rid of a few years ago (  ).Of course, people inevitably try to game the system, so the OPA had to clarify the rules - "No, you can't obtain a higher FIT rate by building a bunch of wooden shacks in a field and reclassifying your PV array as 'rooftop.' Stop being a jackass." The Ontario program even offers a bonus FIT payment for involvement of aboriginal people. This is mostly a "social" thing - trying to make aboriginal communities more self-sufficient, and encouraging aboriginal businesspeople to get involved with renewable energy projects. Ideally, it will also provide experience in deploying renewable power to remote sites, which will be of use in future endeavours (such as mine sites and Arctic military bases, which are often reliant on fossil fuels). Thus, you can imagine an ideal FIT system as one which perfectly prices-in all positive externalities (environmental, social, etc). We can't institute a carbon tax for political reasons, but we can try to offer rewards to low-carbon or high-virtue power sources. Depending on where you live, these higher rates will either be passed on to the consumer directly (which encourages conservation but hinders economic growth and directly harms the poor) or paid out of general tax revenue (cheap electricity is popular among voters, and it's easier to get people on-board with progressive action when the costs are hidden). * France took the opposite approach, favouring integrated-power design in large buildings such as hospitals, rather than grid-feed-in from household rooftops. I agree with this approach - so long as we're allocating resources towards any particular technology, I'd prefer to see it deployed in a way that maximizes EROEI.
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Jan 24, 2013 15:29
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CombatInformatiker posted:The faster we get away from nuclear and coal the better, and any large investment in nuclear power diverts money away from developing clean, renewable energy sources and storage methods. Thus, the production chain for a windmill is probably going to generate radioactive waste. Even if it does not, it's going to involve environmental damage and human suffering, simply as a consequence of the fact that mining in general is a fairly unpleasant activity. We need to look beyond simple categories ("clean" "dirty") and get into actual cost-benefit analysis. For example, someone posted a "deaths per kilowatt-hour, by energy generation type" chart upthread. IIRC it was pretty shoddy (essentially an unsourced blog post using back-of-the-envelope math) but it's indicative of the sort of mental work that you should do before deciding that "technology X deserves my support while technology Y does not."
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Apr 3, 2013 12:43
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CombatInformatiker posted:Keep in mind that there are a lot of countries with high energy demand which do not have the US's luxury of large, uninhabited wastelands where is doesn't really matter if some radiation leaks into the ground. One of the basic principles of the NWMO (organization setting up long-term geological storage for Canada's spent nuclear fuel) was "domestic material only." They recognized that the recipient community would be leery about its new role as "national nuclear dumping ground," and decided that they would rather not salt the wound with the title "international nuclear dumping ground." This has the added benefit of avoiding some potential diplomatic squabbles regarding strategic arms control treaties, avoids logistical difficulties of cross-border shipments, and averts the spectacle of Greenpeace activists chaining themselves to the Ambassador Bridge. Admittedly, it's a bit of a hypocritical stance for Canada to take. We're happy to export Uranium and/or CANDU fuel bundles, but we don't want to deal with the inevitable consequences of such actions. If you want to burn it in your country, then you have to bury it as well. Since someone mentioned groundwater contamination... here's a quote from one of the NWMO's many technical reports: http://www.nwmo.ca/uploads_managed/MediaFiles/1442_nwmotr-2009-12_technicalsummar.pdf posted:Under repository conditions, used fuel exposed to groundwater is expected to dissolve very slowly. A fractional dissolution rate of 10-7 per year (i.e., all the fuel is dissolved in 10 million years) is a conservative but realistic rate of fuel dissolution under repository conditions whereas a dissolution rate of 10-4 per year could only occur if oxygenated groundwaters reached the repository (Shoesmith 2007). In either case, water would first have to breach the long-lived containers and come into contact with the used fuel, and then the used fuel would have to dissolve into the water.
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Apr 4, 2013 12:59
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Frogmanv2 posted:http://www.scientificamerican.com/article.cfm?id=solution-to-renewable-energy-more-renewable-energy A few points that I found interesting:
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Apr 17, 2013 11:52
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Fuschia tude posted:Isn't the whole point of baseload power as a concept that power plants have to be kept running 100% of the time, because the outages due to lack of other sources/peaks in usage can't be predicted with total accuracy, and it takes hours/days for a cold plant to spin up to useful output? The rationale behind the 99.9% threshold is described in the report. It was mostly a matter of economics - costs rise asymptotically as you approach 100% (remember - getting from 90% to 99.9% requires 3x overcapacity). To cover those "missing" 9 hours per year, it's much more feasible to burn fossil fuels or use electricity-pricing schemes to shift demand around.
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Apr 17, 2013 12:30
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silence_kit posted:The bulk doping concentration of a silicon solar cell is probably at most in parts per million. I also ran into a USGS report which predicts some scarcity concerns with exotic solar panel materials (e.g. CIGS thin-film), but which concludes that any scarcity can be easily handled by recovering materials from retired PV cells.
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Jun 6, 2013 23:46
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Paper Mac posted:So, this is a scam, right? Reducing sulphur output from a diesel engine is also a worthwhile goal, but it needs to be done (and largely has been done) at the refinery. Once the sulphur enters the combustion cylinder, it's inevitably going to leave the tailpipe as an oxide (or sulphuric acid, or a complex hydrocarbon, but those are generally worse). They claim that the sulphur is magically getting bound to an ethylene molecule (presumably as thiirane, although they don't identify it as such). Thus, they've managed to "eliminate" sulphur emissions by transforming it into a chemical form which they couldn't (or just didn't bother to) measure. Note also that thiirane itself is flammable and somewhat unstable - if you release it into the wild then that sulphur atom is going to become SO2 anyways. A similar objection applies to any reduction in carbon output. Unless your car is periodically making GBS threads out bricks of graphite, any carbon that enters a combustion chamber is going to leave the tailpipe. Catalysis can convert it into forms that are harder to detect, but it doesn't magically disappear. The entire experiment design seems a bit lazy/silly. Vehicles don't burn diesel at 1 atm with haphazard air supply; they burn it at 15+ atm with a specific fuel-air mixture. Higher pressure means higher temperatures, which tends to provide a more complete combustion (the peak temperature within a diesel-burning cylinder is greater than the HNG+diesel flame that they tested). A Bunsen-burner trial is fine for initial analysis, but a reputable company would have tested their fuel additive in an actual engine before going public with their wild claims about 100% increases in efficiency. Dusseldorf posted:HNG is packed with ‘Exotic Hydrogen’ GulMadred fucked around with this message at 19:55 on Aug 2, 2013 |
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Aug 2, 2013 19:52
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blowfish posted:Said a campaigner for Greenpeace, “The Merkel government doesn’t do enough to protect the climate anymore.” http://www.greenpeace.org/international/en/campaigns/nuclear/ posted:Greenpeace has always fought - and will continue to fight - vigorously against nuclear power because it is an unacceptable risk to the environment and to humanity. The only solution is to halt the expansion of all nuclear power, and for the shutdown of existing plants.
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Aug 3, 2013 12:48
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Placebo Orgasm posted:I forget, was there ever a reason why we don't store the "waste" at the WIPP in New Mexico? More to the point, WIPP simply is too small-potatoes. Its total footprint is similar to that of the proposed Canadian waste repository (but the USA has much more waste to inter, since it runs something like 4x as many reactors). Its primary hoist has a 40-ton capacity; spent-fuel cask designs can easily exceed 100 tons. It doesn't have a radiologically-secure surface factory/lab (which could be used to inspect and repackage waste, if necessary). From what I can find online, it also lacks the sort of kill-on-sight security force which one would expect to find wherever proliferation-risk material is being handled.
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Aug 14, 2013 04:36
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hobbesmaster posted:Do you want him to lie and say there will never be accidents at power plants? Key points:
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Sep 26, 2013 23:36
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Hobo Erotica posted:Are we talking about the water needed to keep the heliostats clean (in which case you'd need the same for PV), or just to spin the turbines? quote:In other words, are you saying this is bad technology, or just a bad place to put a power plant? quote:Does that mean they're not using molten salts? And if so, does that mean it doesn't have overnight storage?
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Sep 27, 2013 04:52
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QuarkJets posted:And what if we required mining/fracking operations to sock away a certain amount of cash for ecological restoration projects? In most of the civilized world, mining permits are already subject to a similar principle:
Edit: whoops, I neglected the second part of your sentence. I know very little about fracking. I think that they're subject to the same rules but (because it's a relatively young business and enjoys political support) the bond amounts are relatively small. Pander posted:I dunno. Even on a per-megawatt-produced basis I'd bet Ivanpah required a lot less construction material than a nuke plant. Nuke plants have a LOT of steel, iron, cement, etc. Uncountable stretches of piping, etc. 290 MW :: 39 000 tons ( 1154 MW :: 110 000 tonnes (UK analysis of AP1000) Edit: the solar numbers here are for a PV facility rather than Ivanpah as I had originally claimed. I'll include an Ivanpah value if/when I get an answer from Gestamp. Of course, a nuclear power plant is also going to require a lot more concrete (and a relatively small amount of costly special alloys). On the other hand, it gets better "mileage" out of its construction materials by maintaining a >90% capacity factor. GulMadred fucked around with this message at 19:22 on Sep 28, 2013 |
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Sep 28, 2013 16:33
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Kafka Esq. posted:It's really sad that NIMBYism in Canada is so strong when the power mix of the two largest provinces are so close to eliminating fossil fuels.
The outreach teams are composed of professionals - scientists, engineers, regulators, sociologists, lawyers - who must sometimes spend weeks or months on-the-road, away from their families, giving presentations to rooms full of skeptical local citizens of #current_city. Some of those citizens will curse them as polluters and poisoners and murderers. Sometimes there will be no public interest, and they'll see only two visitors throughout the entire day. Even on a "good day," they'll spend a lot of time re-narrating material that they've already discussed a hundred times in previous engagements, and fielding various versions of questions that they've heard hundreds of times ("what about the groundwater?" "will it explode like a nuclear bomb?" "can't we just shoot it into the sun?"). It's thankless work, and yet they do it because it needs to be done - onsite storage is not a permanent solution, and it would be deeply irresponsible to accept the status quo. I think that the testimony of the Saugeen Ojibway Nations1 helps to illustrate a few salient points: Saugeen Ojibway Nations (PDF) posted:The very first question in these proceedings concerns the concept of safety. The question was asked about the differences between safety as regulated and safety as perceived and whether OPG’s concept of safety encompassed a broader perspective. quote:As we all now understand, the willing host community concept is a central aspect of social safety and public acceptability and it is a core component of the adaptive phase management approach as it is applied in the Canadian context. And as we heard from Dr. Leiss on Tuesday, it is also now understood as a necessary aspect for the successful siting of any DGR project or other hazardous waste disposal facility. quote:Over the last few days we had a very - a few very clear examples of [trust vs acceptance]. For instance, in the EIS and again in the presentation from OPG, it was noted that the presence of the DGR which directly affects the rock, the first order of creation, may have special meaning to some Aboriginal people and therefore may be seen as incompatible with their worldview and that this might affect how Aboriginal people value the plants and animals they harvest. quote:let us not get trapped by our fears and interests, let us not get fooled by our own intelligence. Let us instead understand the seriousness of the problem and the concerns of others. Let us not rush into decision, but make the best decision, one that we can all live with. 1: For non-Canadians - First Nations (aboriginal) people tend to get hosed over in these sorts of development projects. Their input is ignored, their treaty rights are infringed, their land is used or contaminated without their consent, and they may be forced to wait several decades for an apology (let alone relief/recompense). The fact that they're present at this hearing shows that they have at least some expectation of exerting a positive influence on it; the content of their testimony shows that they're mostly satisfied with the work done to-date (although there are several more issues that they'd like to see addressed before they'll be on-board). GulMadred fucked around with this message at 05:40 on Oct 15, 2013 |
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Oct 15, 2013 05:33
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GrumpyDoctor posted:What is it about this design that makes it unsuitable for non-research reactors? You remember the crazy video that you just saw with the TRIGA, wherein they ramped it up to 160% supercritical within 30ms? You wouldn't want to do that with a conventional reactor. Pool reactors have few moving parts; conventional reactors have (for example) coolant pumps which must keep pace with activity in the core (and which certainly cannot ramp up within 30ms). The TRIGA reactor is passively safe because as it heats up, its reaction rate slows down. In the video, you see a momentary flash (as the reactors hits 340MW output) but it cannot sustain such output - thermal expansion forces its fuel elements away from their optimal configuration. TRIGA cannot boil its coolant water, even at ~2 atmospheres of pressure. A conventional reactor must be able to boil water even at hundreds of atmospheres of pressure (the boiling water is continuously circulated away, so that we can ultimately spin a turbine and generate electricity). If we could somehow "magic away" the negative thermal coefficient, kludge the TRIGA core into a pressure vessel, and give it a coolant loop with proper circulation, we'd run into a new problem - the uranium zirconium hydride fuel used in TRIGA reactors will actually melt before it reached the operational temperature of a conventional BWR. The efficiency of a heat engine depends on the magnitude of the temperature difference, which means that you want your core to run as hot as possible (within the bounds of safety and engineering tolerances, of course). A hypothetical TRIGA reactor (again, ignoring the negative thermal coefficient) which was scaled up so that it generated exactly as much core heat as a conventional reactor, would produce perhaps 60% as much useful electricity. This doesn't mean that pool/research reactors are useless; they can serve as a neutron source for the creation of medical radioisotopes. And they can help to train new generations of scientists. And they generate Cherenkov glow, which everyone agrees is pretty  .
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Oct 29, 2013 15:29
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hobbesmaster posted:Based on Germany the alternative to nuclear is natural gas. "Bloomberg posted:The profit from burning coal increased 3.4 percent to 8.89 euros a megawatt-hour yesterday in Berlin, based on German power, coal and emissions prices for next year. Gas-fired plants generated a loss of 17.40 euros a megawatt-hour, according to data compiled by Bloomberg. "Financial Times posted:The rapid expansion of solar and wind power means coal- and gas-fired plants are left with little to do on sunny and windy days and are increasingly unprofitable to operate.
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Dec 11, 2013 06:38
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Trabisnikof posted:Also German still exports more renewables than imports coal The imported coal is of a higher grade (and thus higher energy content) than the locally-mined stuff (which is almost entirely lignite). If you look at actual electricity output (PDF, page 8), imported coal produced about (106 TWh * 62.6% = 66.36 TWh) compared to 143 TWh for domestic coal (because lignite isn't a great fuel). Note: I'm using 2011 IEA numbers to determine the domestic/import mix for German coal, and splicing that value into the 2012 energy mix statistics. Lignite mining in Germany has increased since 2011, but imports have increased also (sources disagree on the magnitude, due to different reporting rules for intra-EU trade versus global trade). In any case, the 2011-2012 change is not large enough to seriously alter the conclusion. Net German electricity exports in 2012 were 22.5 TWh. If we use the gross export number from the CIA world factbook (66.81 TWh), we need to assume that Germany's exports are more than 99.3% renewable in order to satisfy your claim. The actual data (as examined by Deutsche Umwelthilfe) shows that periods of export (i.e. mid-day peak) coincide with substantial coal-burning. To summarize the report: Germany's electricity export is made possible by the fact that it burns more coal than it actually needs to. The report also shows that output of renewable power has declined from 2012 to 2013, while output of coal-fired power has increased in the same period. And, simultaneous with those changes, electricty exports have grown. If German electricity exports truly represented a renewable surplus being shared with the region, then we should expect them to decline as renewable production declines. tl;dr Your assertion is valid only under an implausibly charitable interpretation of the available data. You should probably double-check your source.
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Dec 13, 2013 14:23
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Trabisnikof posted:The Nuclear Energy Institute claims Nuclear fuel costs + O&M alone: EUR .17kWh. "PDF posted:Fuel cost: $7.5/MWh
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Dec 13, 2013 19:08
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Arghy posted:How feasible is it to dig into the earth and create a giant tunnel of geothermal heat? Boreholes for power generation wouldn't make much sense. Let's say that you have a gradient of 30K/km (global average). The deepest borehole in the world might give you 260K (in fact it gave much less because they deliberately chose a "cold" location so as to simplify the engineering challenges). The maximum efficiency of a heat engine depends on its input temperature. Even assuming that you could magically circulate fluid from the borehole bottom without any loss of heat, you'd be constrained to a maximum thermal efficiency of 47%, which is much lower than any modern power plant (although it's a bit better than first-generation nuclear reactors). Note that this calculation assumes that you have a big convenient heat sink nearby, such as a river. You'll also need to expend energy on pumps - moving fluid 12 km vertically isn't fun. The next problem is capacity. Output (or "production") is limited by thermal conductivity of rock, and your effective "catchment diameter" may be as low as 10m. You can't simply run more fluid through your borehole - you'd thermally deplete it and then need to shutdown the power plant until it naturally replenishes. If you want more power then you need to drill a lot of holes. Each borehole is going to cost a few tens of millions (assuming that you're going deep - a shallow hole is cheaper but yields low temperature and therefore low efficiency). I don't know whether you'd ever be able to repay the capital costs of drilling. Insurance would also be a problem, and your construction permit might get held up for years due to the difficulty of assessing long-term environmental impact (e.g. "there's a teensy chance that we might trigger earthquakes, but the risk would probably be confined to a 200km radius"). Here's a real-world example. They drilled down 2.5 km and obtained 450kW of heat. If they tried to harness that low-grade heat into useful work, they might have been able to obtain 100kW. That's the equivalent of the muscle power of 200 athletes, or about half of the engine power of one Ford truck.
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Jan 10, 2014 12:03
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blowfish posted:Problem: you need like 3-4 times overcapacity at least to get reasonably secure base load power, and you need to add storage to do that.
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Jan 12, 2014 10:28
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Trabisnikof posted:Most modern CSP uses molten salt and not water. Bechtel (you know the same ones who make nuclear plants) has several new CSP plants going up in the USA that all use molten salt and in fact I'm not aware of any that require water to reflect upon. Unless you mean closed loop systems, which then a CSP plant handles a big storm just as well as an oil refinery or anything else with lots of pipes. This is indeed a potential problem, because heliostats can be damaged by high winds or precipitation (we're worried mostly about freezing rain and hailstones rather than thunderstorms, but w/e), and any persistent cloud cover will diminish the facility's output. The standard approach is "just build it in the desert - deserts don't get much rain; avoid hurricane or tornado zones; find a spot reasonably close to civilization so that you don't blow your entire budget on roads and transmission lines; a local water source is nice (for mirror cleaning and evaporative cooling) but you can live without it." Ardennes posted:Even if you disagree with their energy policies (which is fine), it doesn't mean the population is a bunch of shitheads. The webpage I linked uses the present tense, but it was actually written in 2006 (after the borehole was complete but long before the surface facilities were ready for operation). They were using a single coaxial design, so the pipe needed to contain an inner insulating sleeve to contain the hot (rising) output water - the cold (descending) input water would occupy the space between the inner sleeve and the outer metal pipe. Unfortunately, the plastic-reinforced fiberglass material proved to be structurally inadequate. This is admittedly a very tricky problem - you need to balance water pressure, varying thermal loads, possible erosive/corrosive effects, and the non-trivial mass of a 2500m-long fiberglass pipe (and also the problem of quality-control as you insert and weld each pipe section - does the welding technique create local weaknesses? Are you sure that the welds are watertight?). You can model the variables on a computer and run simulations, but eventually you need to deploy it in the real world and see what happens. Well, there was a concurrent effort underway in Arnsberg (for a local swimming pool), and their inner pipe (using the same material) suffered structural failure during installation. gently caress. Well, no sense in repeating the same process and encountering the same error. Let's check our math, inspect our materials, and proceed carefully. Nonetheless, the inner pipe got stuck just before reaching the 2000m mark. Presumably they attempted to jimmy it around a bit, but eventually gave up (I gather that one of the pipes was slightly kinked and so there was no practical way to "work around the problem"). Okay, we've hit a snag. But we still have a deep borehole and a coaxial pipe, and we can theoretically circulate water to a depth of 2000m. Maybe that's good enough? Nope. The project originally called for an outlet temperature of 85C. The reduced-depth arrangement could theoretically deliver 60C. It was observed at 35C (presumably due to leaks in the inner sleeve which allowed the hot and cold water to mix). 35C is worthless. Even under very generous assumptions assumption (e.g. rebuilding the inner pipe using unobtainium), the analysts concluded that the project was economically infeasible - the best approach was just to walk away from the project and stop throwing money at it. Note: honestly though, this isn't an especially bad story. We should recall that this was a research project undertaken by a university. It was a tiny vanity project, and its failure did not cause a significant uptick in fossil fuel usage. It provided employment for skilled labourers; it proved/demonstrated the feasibility of minimally-disruptive drilling techniques in a cluttered urban environment (which will doubtless be useful for future geothermal ventures). It delivered some core samples that probably made a geologist happy. It may have failed in its stated purpose (and doubtless embarassed a fairly prestigious engineering department), but in so doing it yielded some good material-science data and lessons which will guide future efforts. Such as: "find a really good insulating+structural material for the inner pipe, or maybe use a metallic inner pipe with an insulating liner," or "use multiple adjacent boreholes instead of a single-hole coaxial setup," or "use a double-walled steel pipe with an intermediary vacuum layer like the one at Weggis," or "setup a shallow geothermal field with a low outlet temperature and use it exclusively for winter heating while you power your air conditioner with a roof-mounted PV array or miniature biogas plant or whatever." Finally - Wikipedia has a photograph of the site where the wellhead unit would have been installed. You can see the facility's water pipes terminating forlornly a few meters away from the borehole, forever bereft of the geothermal bounty that they were promised. A silent 23-million Euro testament to the fact that new technologies bring new challenges.
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Jul 9, 2014 10:23
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hobbesmaster posted:It operates a 700C and has 70% energy efficiency which is pretty miserable. Really cool, don't see it being deployed everywhere though. 2000000 Wh / 67500 l = 29.6 Wh/l That's a third the density of the venerable lead-acid cell. If you took all of the generating plants offline and wanted to power the USA for one day using Ambri batteries (assuming 100% efficiency) then you'd need: 3886400000 MWh / 365 = 10647671 MWh 10647671 MWh / 29.6 Wh/l = 359718 Ml 359718 Ml / 1200 Ml = 299.765 300 Astrodomes filled (as in "stacked to the rafters") with uncomfortably hot batteries.
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Jul 11, 2014 22:14
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Raldikuk posted:I really don't get why they decided to reduce gas by 10.5 TWh in favor of pumping up coal. Imagine that you own a utility company in Germany:
Edit: here's a succinct summary. 
GulMadred fucked around with this message at 15:54 on Jul 12, 2014 |
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Jul 12, 2014 15:50
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QuarkJets posted:Okay, but why not? Your video seems to be about reducing fossil fuel use in Australia, so why not build nuclear power plants that use Australian-produced uranium? You're trying to use an educational approach, so it seems like a really good opportunity to push a cheap and safe energy source whose widespread implementation is restricted only by a lack of education It's a question of focus. If your goal is "educate the public about power" then, sure - debunk some atoms. If your goal is "stop burning coal" and your means is "educate the public about power" then you avoid the subject. Analogy: if a Democratic politician in the USA wants to reduce crime then they should talk about sentencing reform, work-training programs, decriminalization, investment in education, social safety nets, etc... They should say nothing whatsoever about gun control.
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Jul 30, 2014 11:15
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LemonDrizzle posted:Energiewende and the decision to abandon nuclear continues to be a rousing success for Germany: it has now been reduced to begging Sweden to keep its coal mines open so the country doesn't start experiencing blackouts.
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Nov 25, 2014 12:49
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Maybe the "divestment" strategy is some sort of Enron game in which the assets are spun off into a shell company but nothing actually changes.
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OwlFancier posted:It's almost as bad as DHMO.
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Mar 19, 2015 03:48
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RDevz posted:Getting the biomass to the power station is another massive problem. Its energy density is something like 2/3 of the GJ/tonne that you get from coal (c. 16 vs. c. 24), which means you need more ships and more trains to get it to where it's needed. Trabisnikof posted:The energy cost to ship something in bulk by train can be pretty low. But then again, most of the time you mine-mouth that poo poo and site your Ag based biomass facility in Ag country and your city-dump based biogas facility near the city dump. Large-scale use of biomass wouldn't suffer quite the same limitations as lignite (it has an even lower energy density than lignite, but it would presumably be exempt from carbon tariffs). Nonetheless, it would still be a regional commodity (with regional supply/demand and pricing issues) rather than a globally fungible one.
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Apr 28, 2015 23:06
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QuarkJets posted:Coincidentally, Earth only has about 150 square kilometers of actual land.  quote:How did you come to 1%? pre:22 126 TWh/year (global electricity generation for 2011) = 79 653 600 000 000 000 000 J/year 2 W/m2 (your own stat for wind turbines; assumes 6m/s average windspeed) = 63 113 852 J/year/m2 79 653 600 000 000 000 000 J/year ÷ 63 113 852 J/year/m2 = 1 262 062 090 585 m2 = 1 262 062 km2 1 262 062 km2 (calculated wind generation footprint) ÷ 148 940 000 km2 (Earth land area) = 0.00847
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Apr 30, 2015 09:01
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Morbus posted:... the US was relatively enthusiastic about nuclear power in Iran... 
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Nov 20, 2015 05:43
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Tias posted:going nuclear brings with it the potential of meltdowns and material depletion that can end our species  Oh, yeah? Well what about the equally plausible scenario in which a solar panel goes rogue and begins rampantly absorbing all available sources of light - leaving the Sun a burnt-out cinder in the sky? Seriously - the numbers don't work: According to the World Nuclear Association, there were 438 reactors operating at the beginning of this month. The EIA says that nuclear reactors generated 2,344.806 PWh of electricity in 2012, out of a total of 21,531.709 PWh. So let's crudely boost that number. We now have 4022 reactors, supplying all of the world's electricity. Now let's push every one of them through the worst-case nuclear meltdown disaster known to mankind. Ignore the fact that most of those reactors aren't RBMK and that they have secondary containment systems. Long-running international investigation and review work has estimated the eventual death toll from Chernobyl at 4000. But let's apply the precautionary principle and assume the worst. There was a report published a few years ago which claimed 985,000 deaths. It had a few methodological flaws, and peer review wasn't exactly kind to it, but let's ignore that and just round it off to a million corpses. For simplicity, let's also assume that all of those people die immediately of acute radiation poisoning. The actual results involve stuff like "guy should have died at 70 of heart failure, but instead died at 68 of thyroid cancer", which is less exciting from a doomsday perspective. So: every power plant on the planet is replaced by a nuclear reactor. Each reactor spontaneously turns itself Russian, overrides all of its safety mechanisms, and shits itself sideways until the desperate survivors manage to entomb it in concrete. 4,022,000,000 people die. The three billion survivors are going to be pretty upset, and life is going to be pretty lovely for a while without any electricity. But you're going to need bigger numbers if you want to actually kill off the species. GulMadred fucked around with this message at 15:26 on Nov 29, 2015 |
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Nov 29, 2015 15:24
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