tag:blogger.com,1999:blog-7403735595451011590.post1650696105065787816..comments2022-11-13T20:13:13.070+11:00Comments on Thisness of a that: Don't ask little of me - you might get it.Unknownnoreply@blogger.comBlogger4125tag:blogger.com,1999:blog-7403735595451011590.post-19842403529321313472012-08-21T05:40:11.189+10:002012-08-21T05:40:11.189+10:00Hi Jonathon... yes, I didn't mention the 2% bi...Hi Jonathon... yes, I didn't mention the 2% biomass because the post was more general.<br /><br />I see where you're coming from re the plan to use biomass. I'm not sure of the details, but I don't dismiss the biomass suggestion. NSW's ethanol is produced from biomass and all sugar mills generate bagasse that is used to produce electricity and could be ramped up further. Waste transfer stations in Sydney send biomass to Hunter Valley coal generators. So we already have the basis for a biomass industry. <br /><br />You probably know that I really like the idea of pumped hydro, so I expect that we would see some of that at some stage. Also, as the vehicle sector is electrified, there are those potentials for car batteries to act as a back up. The BZE plan was written two years ago, and was based on the premise of a fast implementation (across 10 years) so it works within the constraint of existing technology. As you say, by the time we need that kind of backup, it's likely that other solutions will be more practical.<br /><br />I agree with you that the transition of electricity to 100% renewables is likely to be phased over several decades and all kinds of things will come into play along the way. <br /><br />The most important value of the BZE plan was that it got the ball rolling and demonstrated that there is a viable version of 100% renewable electricity. The govt is currently letting a contract to do its own study to demonstrate how Australia's electricity could be 100% renewable by 2030 or 2050.<br /><br />I do see CST as commercially viable. The Gemasolar plant provides enough power for 25,000 homes - that's five towns the size of Renmark. The Tonopah plant currently under construction in Nevada is three times as big. Currently there are 20+ CST projects underway worldwide with a total 17.54GW capacity. Among others, the Saudis are taking a lead... http://www.constructionweekonline.com/article-17709-saudi-group-close-to-winning-500m-solar-contract/<br /><br />I read a study somewhere that compared the economics of CST without molten salt compared with the molten salt version. Apparently the molten salt version was 20% more cost effective in the longer term because of the capacity to generate power into the evenings. [Not sure I expressed that accurately, but you get the picture.]<br /><br />You're up late, and I'm up early!Gillian Kinghttps://www.blogger.com/profile/10044947029552421347noreply@blogger.comtag:blogger.com,1999:blog-7403735595451011590.post-82660041507187680382012-08-21T05:13:10.532+10:002012-08-21T05:13:10.532+10:00Hi Jonathon,
Yes, this post gives a very broad br...Hi Jonathon,<br /><br />Yes, this post gives a very broad brush view of the BZE proposal. From what I understand, the mix of CST and wind that is proposed is more economic than achieving full coverage with wind alone. <br /><br />I'm comfortable calling CST dispatchable because I expect that there would be sufficient capacity (or over capacity) to cover a large proportion of unusual demands. The graphs on pages 80-81 show the modelling for how the proposed mix of wind, CST, and some hydro/biomass, would meet expected demand. I'm sure that this isn't definitive and there will be a lot of ongoing modelling of various supply/demand scenarios as we make the transition. <br /><br />The issue of whether CST and wind, together, should be called 'dispatchable' or 'predictable' seems like a fine point that depends on how the grid is run. Both terms need to come into the discussion for those people who have a fairly simple view that coal generators run 24/7 delivering a steady flow of electricity. As you know, all power stations work at less than 100% capacity and grids need to cope with fluctuations in supply.<br /><br />As you say, "as long as fossil fuels are still in use" they'll be used to provide capacity. The BZE plan is very ambitious in aiming at 100% renewables. Strategically, it's a good position to take because if it shows that the most ambitious target is possible, it also supports less ambitious targets. Gillian Kinghttps://www.blogger.com/profile/10044947029552421347noreply@blogger.comtag:blogger.com,1999:blog-7403735595451011590.post-46182822302644320752012-08-20T23:23:36.144+10:002012-08-20T23:23:36.144+10:00The campaign and proposal I read from the BZE peop...The campaign and proposal I read from the BZE people ( http://media.beyondzeroemissions.org/ZCA2020_Stationary_Energy_Report_v1.pdf ) actually proposes using wheat chaff on site in place of sunlight for "contingency" to cover 2% of annual electric demand in periods when the heat storage runs out and there's but a feeble breeze. That 2% figure reflects highly optimistic assumptions about CST heat storage : 5% to 15% is more realistic. Crop residue is indeed renewable, and I suppose it's technically feasible to do this, but it seems to me prohibitive (in transport costs alone) to establish a new industry to collect and distribute and generate power from crop residues, whether for 2% or 10% of annual electric demand.<br /><br />Given that an enormous fossil fuel based electricity industry with immense capital already exists; given a biogas industry (heavily in development in Europe, if not here) that readily integrates with the fossil gas infrastructure; given the potential to expand existing electric power storage techniques such as pumped hydro; and given rapid technological development worldwide of numerous new ways to store excess electricity for a still, cloudy day, I doubt very much that we will see either storage of solar heat for periods of weeks *or* the "co-fired wheat chaff". Crop residue is, at best, a minor on-farm fuel or feedstock for biogas.<br /><br />We must push for ever-deeper integration of intermittent renewables into the existing electric power system while phasing out the dirtiest fossil fuel burning components. In the short term this means brown coal (though to date it's black coal, as an expensive globally traded commodity, that gets pushed out through market merit order) but ultimately of course it means fossil gas as well.<br /><br />Only when all the coal-fired power stations are retired does it make sense to worry about whether the remaining fuel used to bridge the still, cloudy days (as little as 10% or 15% of total demand in Australia) is fossil or renewable.Jonathan Maddoxnoreply@blogger.comtag:blogger.com,1999:blog-7403735595451011590.post-77646314839372183442012-08-20T23:23:05.327+10:002012-08-20T23:23:05.327+10:00I have a little bit of a problem with this bit:
&...I have a little bit of a problem with this bit:<br /><br />"Together, CST and wind can deliver reliable baseload power that is sufficiently flexible to dispatch power at short notice and cope with variability of demand and changing weather conditions."<br /><br />I'm always on your side of this argument. I don't believe that baseload generators are necessary and I'm certain that 80% or 90% of Australia's total power demand may, eventually, be sourced directly from the sun and the wind using the technologies mentioned. It is reasonable to credit wind with being "reliable baseload equivalent" when, by spreading wind generators widely enough across a continent, there is a specific power level above which wind will reliably generate for 90% of the time -- since no fossil-fuel or nuclear baseload power station can guarantee better than 90% capacity factor or no unscheduled downtime. Of course if you build that much wind capacity, most of the time it will be generating rather more, so if you install enough to guarantee most of your "baseload" demand you'll have surplus power for much of the time.<br /><br />But you can't describe either technology as "flexible to dispatch power at short notice" -- rather, they're generally very predictable. You do know several days in advance when there will be widespread calm or cloud. (You also can't really describe concentrating solar thermal heat storage electricity as "off the shelf" ... it's an emerging technology, very new).<br /><br />In the case of heat storage I suppose you can indeed dispatch it until the heat store is depleted -- though in practice I expect the solar collectors and turbines will be scaled such that there's little excess to store over what is used during the day. BZE's charts show overnight generation depleting the thermal store steadily overnight but only from 80% down to 70% of the total storage available -- in other words they expect to have storage capacity of solar heat sufficient to generate full power for up to ten days from a full charge. Solar collectors and the storage are expensive; turbines are indeed off-the-shelf and relatively cheap, so any early developers would maximise daytime power before spending big on surplus collectors, tanks and insulation in anticipation of a cloudy week that happens once or twice a year. As long as fossil fuels are still in use, storage of solar heat will for economic reasons mostly be used to cover evening demand peaks in the few hours after sunset. Since the heat store can be charged only by direct sunlight (or combustion of fuel delivered to the site) it is quite vulnerable to periods of overcast.<br />Jonathan Maddoxnoreply@blogger.com