Storage Plus – Exploring the Potential for Energy Storage and Generation Hybrids

Storage Plus – Exploring the Potential for Energy Storage and Generation Hybrids

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>>Caitlyn: So, you can see here that there's  a live set of technologies that can be   included in a hybrid energy system and these are  being considered for different applications and   purposes today. They can also be connected  at different levels of the energy system   including on the volt grid or in a distributed  application, as Sarah mentioned in her   introduction. Of course, the very popular  and remote microgrid applications for those   regions that are not fully connected to a larger  grid network. Finally, hybrids can be designed  

to generate electricity or other co-products  including energy products but also non-energy   products. So, this is really a huge suite of  technologies and a huge suite of applications,   and to try to draw some bounds around this  and make it more of a manageable presentation. The focus today will really be on renewable  energy generation sources combined with energy   storage technologies that are combined  to form a hybrid technology that is   connected to the bulk power system. So, we're  really talking about utility scale deployments   of renewable energy and storage combinations or,  perhaps, multiple renewable energy technologies   being combined together. The focus today  is also only on hybrid systems that produce  

electricity as their only output. This is really  a subset of the hybrid being considered today.   I don't mean to suggest that any of the other  hybrid applications are less valid. Just   making it clear kind of what the focus of this  presentation and our research to date has been. So, if we look at the technology  combinations that have been proposed   in the U.S. and internationally, what we see is  that there really are a diverse set of technology   combinations that are being considered.  So, this noel diagram divides technologies   into three categories. The blue nodes are the  variable renewable resources including wind, PV,  

and run-of-river hydropower. The green icons show  energy storage technologies bucketed into pretty   large categories, but ultimately that's really  those that are – this captures all of the energy   storage technologies that are being deployed on  the grid today. So, batteries, compressed air,   pumped storage hydropower, even things like  ultracapacitors and flywheels. Finally,   hybrid energy storage systems where you  would be combining two of these energy   storage technologies together into a hybrid  of its own based on energy storage only. Finally, the orange icons are what we would refer  to sort of less variable renewable resources.  

These are renewable resources that are more  dispatchable such as geothermal and reservoir   hydropower, but it also includes a number of  hybrids in themselves. So, PV plus battery is   showing up here as its own icon because there  have been proposals that look at combining PV   battery with other resources rather than stopping  once you get two technologies together that would   form your hybrid system. Similarly, for wind plus  mechanical storage which could be compressed air   energy storage or pumped storage hydropower,  for example, and also concentrating solar power   with thermal storage. These might be hybrids  in themselves, but they also can be combined  

with other technologies to try to further increase  the value that they offer to the energy systems. So, if you look at the arcs that are  connecting these various nodes, we see   that there is a huge number of technology  combinations that have been proposed.   Most of the arcs are coming out of the wind and  PV nodes, which I think speaks to their cost   competitiveness on their own, but also their  declining value as the penetration increases.  

So, there's more of the motivation to be  combining these wind and PV resources with   other technologies that can try to avoid some of  the declines that we would see otherwise in terms   of the energy value they offer, in terms of their  alignments with demand, and things like that. We also see that, in many cases, we do tend  to propose combining these variable resources,   the blue nodes, with energy storage technologies,  in green. But also blue to orange, blue to green,   orange to green. Really every combination  exists. All of these type of systems are   ultimately motivated by sort of two common  factors. You're either looking to combine   technologies whose resource profiles  are complementary of one another,   but they're generating at different times of the  day, different times of the year, for example.   That's an application for PV/wind amortization  or PV run-of-river hydropower generation hybrid.

The second motivation is really to look at  technology combinations where the capabilities   are complementary to one another. So, this helps  explain those VRE plus storage hybrid systems   where you're combining low-cost, low-emitting  resources that can generate electricity for   you with an energy storage technology that helps  you make it more dispatchable, more controllable,   and shift that energy generation into  the times of greatest spread need.   So, while there are many energy combinations  being considered, they really can be explained   by just those two motivations: complementary  resource profiles or complementary capabilities. So, the key questions related to hybridization.  This is sort of a subset of what I hear most  

often. I think it is consistent with  what we just saw in the poll responses.   As industry interest in these in these  generation-plus-storage hybrid grows,   we want to try to understand what  is the underlying motivation.   Is this interest driven by incentives or are there  costs and value synergies that are really driving   hybrid systems, which would make them  more long-lasting as a grid solution?   What are the important aspects of hybridization  that influence the competitiveness especially   when you compare a hybrid project against an  independent deployment? So, separating your PV   and battery into their own deployments rather  than coupling them into a hybrid configuration.

Third, under what conditions does it  make sense to combine these utility-scale   generation and storage technologies? Are there  thresholds that help us understand when hybrids   really kind of tip the scales and become the  competitive technology going forward? Finally,   does the optimal hybrid project  vary based on perspective? So,   in terms of if you're the plant  owner or if you're the grid operator,   do you want to see different characteristics  in your hybrid systems on the grid? The key takeaways from the presentation –  this is sort of getting ahead of myself,   but I just wanted to put the punchline at  the heart to kind of tee up what we'll be   talking about for the rest of the presentation.  First, what we're seeing internationally and,   again, consistent with your poll responses  is that hybrid projects combining PV, wind,   and storage in various combinations appear  to be the most commercially viable today,   but we do see a very wide range of hybrid  systems that are being proposed and built,   especially in the grids that are growing  to meet increasing electricity demand. The second key takeaway is that adding storage to  variable resources can facilitate many benefits in   the form or renewable energy integration, which  means both aligning your resources with a load,   but also mitigating some of the short-term  variabilities that we would see otherwise in   variable resources. Second, increasing capacity  factors. So, our total output goes up when we're   able to capture energy that would otherwise be  wasted. Third, by combining these resources, we're  

able to localize some of the high-value services.  So, one power plant can provide both the energy   and capacity and ancillary services rather than  relying on different projects to provide those   different services. Finally, as Sarah mentioned,  cost savings can be realized especially for   those cost categories that are applied on a per  project basis rather than a per technology basis. Finally, I do just want to note that many of  the benefits attributed to hybrid systems,   including some of those in the bullets just above,   can also be achieved with separate projects  that are coordinated at the grid level. So,   while there's a lot of interest in hybrid systems  and they do offer a lot of value, I do just want   to make it clear that they're not always the  right answer. There are greater benefits that   can be achieved through increased flexibility in  separate projects under certain grid conditions.

So, I have just a couple of slides walking through  some of what we're seeing today on the grid both   in terms of the projects that are online and also  those that are being proposed for interconnection   today. So, these are really the near-term hybrid  applications, trying to understand what they look   like today, and how they might evolve over the  next few years using the U.S. as an example. So, this chart here shows the  capacities for hybrids and   co-located resource projects in the United  States that were online at the end of 2019.  

So, this is consistent with what we've already  talked about. The technology combinations that   appear to be commercially viable today include  combinations of PV, wind, and storage technologies   with select applications for fossil and storage  applications as well. What we see if we just look   at a single row for the PV storage projects, on  the far right-hand side, we start to get a sense   of what the storage deployments look like when  combined with PV or with wind in the next row. So, PV plus storage tend to involve modestly-sized  battery storage technologies. The average duration  

is shown here as two-point-six hours. That's  really sort of a weighting factor in general.   Most of these PV battery projects are using  four-hour battery technologies to couple with   the PV. Sarah alluded to this as because of  declining cost, but also the value associated   with being able to stand at peak time period in  the late afternoon and into the early evening. Wind plus storage projects tend to have  shorter duration storage associated with   them. That's because, in general, these  hybrid projects are designed to try to  

capture ancillary services benefits,  which occur over shorter time scales. So,   there isn't as much of a need or benefit  of having a four-hour storage technology   when you can use something much shorter  to capture this ancillary services value. Finally, the bottom row plays out that you  don't need storage, actually, to form a hybrid   system. What we're seeing in the U.S. and also  internationally is that PV/wind combinations   are very common as well. This is, again,  trying to capture that complementarity and   when the PV and wind are generating. So, it's very  beneficial if you can find a place where the PV is   great during the day, of course, but then  the wind is maybe blowing more at nighttime,   and that way you can maximize your utilization of  the transmission network. You can also maximize  

your use of land, in that case, as you intersperse  the PV panels around your wind turbines,   trying to use that land as efficiently as  possible and also your transmission networks. So,   they're two of the mains and strengths that we see  in trying to build new generation technologies. As we look into the near term, we see heart  changes in what we expect for PV, battery,   and wind storage hybrid systems. At this point,  to both the fact that we expect hybrid systems to  

capture a growing share of new capacity but also  that their role will be evolving somewhat. So, we   see that a lot of PV projects are being proposed  to be coupled with storage. This speaks to the   synergies between PV and battery technologies  that I'll cover in a couple of slides. A smaller   share of wind and wind projects are being proposed  for coupling with storage, but we are also seeing   a move towards these longer duration storage  technologies in the proposed projects. So, wind  

might be moving closer to the model that we're  seeing for PV and that you use in the battery   not only for these ancillary services products  but also for some energy shifting applications. In terms of what's driving these trends, I  think there's a variety of factors. Policy   is playing a role in the United States based on  the incentives that we have to reduce the battery   cost when it's coupled with renewable storage –  sorry, with renewable generation. But it's also   being driven by great needs. These independent  PV and wind projects are losing their value as   more and more of it enters the grid, and storage  can help mitigate some of that declining value.   We're also seeing that there are cost energies  that help drive some of these deployments. So,  

if you can share costs between then,  that means you can build PV and battery   together at a lower cost than if  you were to build them separately. Finally, just one thing to point out is that  – it's a little bit hidden in this chart,   but the amount of standalone storage that's  being proposed to be built is also larger than   what we're seeing in these hybrid applications.  So, again, not to say that hybrids will be the   only thing that's built in the future. Standalone  storage still has its own value as long as – in   addition to the standalone PV and wind which we're  seeing kind of these light shades on this chart.

In terms of how these projects are  being compensated, there are a few   different models for the power purchase  agreement prices that we're observing,   in this case, for PV-plus-storage projects.  In general, on the Continental United States,   we're seeing sort of the larger grid network in  the United States, we're seeing a convergence   towards about $30.00 per megawatt hour for the  PPA prices. This reflects a variety of different   models. In some cases, the storage is just bundled  into the energy price and it's compensated similar  

to how the PV would be. So, we're really just  looking at the increased energy production   as justifying the adding of the storage  component to the hybrid systems. In different models, we're actually carving out  the storage to be treated slightly differently.   So, it is receiving that energy revenue. But  maybe it's just eating most of its energy   revenue during peak periods, and that's showing  up in the PPA agreements where we see that the   prices are very high in the afternoons throughout  the summer, for example. Presumably, that's where  

storage is really capturing all of the value and  justifying the inclusion and the hybrid project. A new model that's emerging in the United States  is actually to carve out separate compensation for   the battery based on the capacity contribution.  So, these are six payments that basically say,   "We want the storage to be available at  these very high stress periods for the grid.   We will offer you a very large payment to  have that storage available." In that case,   that's folded into a PPA agreement. That's  where storage is earning its keep and all   of the additional energy production that  occurred throughout the year, that's just   sort of a benefit on top of all of the capacity  compensation that's being made to the storage.

Finally, before I move into kind of the ongoing  research, just a look internationally. So,   rather than being restricted to the U.S.,  looking abroad to see what type of hybrid   projects we're seeing there as well. In one  sense, it's more of the same. As Sarah mentioned,   there's expected to be a significant growth in  PV wind hybrids in India, potentially reaching   almost 12-gigwatt system in the next couple  of years. Again, trying to leverage that   maximizing approach to using our land and our  transmission networks efficiently. So, this was   sort of more of what we're seeing in the United  States but at a larger scale internationally.

We're also seeing a diverse set of hybrid  projects, some of which are not competitive   in the U.S. to date. This is a PV/CSP hybrid that  is being built in Africa, that's meant to operate   as sort of base low plant there, again with  very low emissions and very high reliability.   Finally, we're increasingly seeing proposals  of projects where PV is being floated on   hydropower reservoirs to try to maximize  some of the efficiency gains of having   the cooling of the reservoir coupled  with the PV helping to avoid evaporation.  

More on this later when Sika presents  as the second panelist today. But just a couple of slides highlighting  the research that NREL has been doing around   understanding the motivations for hybrid systems.  This is going to be focused on solar-plus-storage   projects. I think that's where a lot of the  momentum is in the United States today. But in   general, some of this can be expanded into other  renewable energies-plus-storage projects as well. So, the first point to make is just that the  how you form your hybrid system can make a   big difference in terms of the types of synergies  you're trying to capture relative to independent   projects. One model uses separate inverters  for both your PV and your battery technology.  

This offers additional flexibility, and it also  allows us to use the existing participation   models today. So, in this case, you can use the  PV and treat it as an intermittent resource in   the way that we already do when we connect  PV to the grid. You then treat your battery   separately as a storage technology. So, you're  leveraging those existing participation models.   Each resource can really operate in the way  that maximizes its value, and maybe you're   trying to understand how they work together  but, ultimately, you’re able to operate each   of them in the way that is most beneficial and,  therefore, maximizes the value of the plan.

The other model is to actually have the PV  and battery technologies share an inverter.   This introduces new cost savings that can  be leveraged. It also introduces new value   synergies in the sense that you can capture more  of that PV generation and use it at a later time   at a higher efficiency relative  to having two separate inverters.  

But this also introduces some new interconnection  challenges. How do you treat this resource where   the inverter is representing both the variable  resource and the storage technology? So,   flow is happening in both directions. It's  dispatchable, but it's also not entirely firm.   So, while there are additional benefits here,  there's also potentially additional challenges   when you move into the so-called  DC coupled PV/battery systems. In terms of the motivations for both of these  technologies, I think the main one is really   trying to capture the shared cost and, therefore,  reduce the total project cost. The panels to focus   on here is the comparison between the hybrid  and the middle, and separate projects on the   right. So, in this case, we're seeing that hybrid  projects are cheaper because the stacked bars   are lower than if you were to deploy similar  projects separately on the both power system.  

The main reasons for these reduced costs have to  do with sharing the electrical balance of system   cost, which is, again, applied for projects  for simplifying things by having all of this   deployed at one time and being able to install it  together, which reduces the total project cost. In the case of the DC coupled system that's  been mentioned on the previous slide,   there's additional cost savings that  can be captured if you're avoiding   one of the inverters that would otherwise  have to be built. In this case, you could   choose either to install a PV inverter or a  battery inverter. They would both work and it   would both reduce your total project cost since  you're just avoiding that hardware component. The second motivation _____ is looking into  these value synergies. There are many of these,  

especially when you start to couple PV  and battery systems together. The first   is highlighted on the left. This is sort  of a dispatched plot where you can see   the legend at the bottom. But in general,  the blue is showing you battery discharge.   The warm shades are showing you the available  PV resource. What we're seeing is that in the  

middle of this day, the PV resource declines  rapidly. The battery is able to absorb some of   that reduction and output so that we don't miss  these periods when there might be a lot of value   or when the grid is counting on the PV  resource being available. For in this case,   the battery's really helping to improve  dispatchability and also avoid any forecast   errors or periods of low radiance in the middle of  the day when the PV resource would be beneficial. Another benefit is looking at capacity factor  improvements. So, increases in overall output.   Here, what we're seeing is that the inverter  is capping the total output, and all of the   yellow bars here are wasted energy that, if  we weren't in a hybrid, it would just be lost.   In the hybrid case, though, we can divert this  energy into the battery and therefore make it   available later in the day, later in the evening  periods when solar is no longer available but   demand is high. So, we're not only increasing  the capacity factor, but we're also enabling  

energy shifting, which is making the PV resource  available when we need it to meet our loads. This is a dynamic that's especially important  when we get to higher PV penetration.   Maybe not as important in the near  term when we haven't yet shifted the   peak demand into that high stress  period into the evening hours. So,   again, just noting that hybrids aren't necessarily  the right answer until we've gotten to this higher   PV penetration and unless we're building our  systems in a way that's really enabling us to   shift extra energy into those hours of high stress  into the hours when we really need it on the grid. So, if we put all this information together and  try to understand the deployment potential for   PV/battery, this is an example output from what  we've recently done in our research planning   modeling tools at NREL basic to what we're  seeing as we look forward in time. If we assume   those cost savings I presented, if we assume those  value synergies or we allow those value synergies   to be represented rather, we'd see significant  potential for hybrid deployment. So, by 2050,  

almost a third of our total PV capacity is  actually taking this hybrid configuration   rather than separate deployment. So, it's  capturing those cost savings and also the   value synergies. It's not completely replacing  PV, but it is serving a major role on the grid,   showing that this potential for hybrid deployment  really does grow over time, especially after   technology costs come down, especially as we're  able to share costs between the two projects.

So, this is just the same key takeaway  slide I presented at the beginning.   Again, what we're seeing is that PV, wind, and  batteries are sort of the most common projects   to be deployed in hybrid configurations today and  in the near term. This is because of the variety   of benefits that they can produce by enabling  renewable energy integration, making it easier   to accommodate additional variable resources on  the grid, increasing the total renewable output   which can grow to a factor of 50 percent or  more if you're sizing your components correctly,   being able to capture these high-value services,  and then, of course, the cost savings that can be   achieved by combining these technologies  into a single project. So, from there,   I'll hand it over to Sika, who's going to talk  about a slightly different hybrid technology. >>Sika: Thanks, Caitlyn. So,  as my slides are pulled up,   I'll be kind of just specifically focusing  on some research that we've been doing,   exploring the operational benefits of  floating solar and hydropower hybrids. So,  

there's been a lot of interest globally in  floating solar specifically, floating solar paired   with hydropower because of perceived  economic, environmental, and social benefits.   But this really limited research out there  on the potential value of these systems   to potential adopters with this technology. So,  in this presentation, I'll kind of quickly walk   through some of the research we've done on that.  But before I go there, I will provide kind of some  

background on what the technology is in the first  place for those who might not have heard of it,   and then provide an update on the current market  landscape for this technology. Next slide, please. So, what is floating solar, also  known as FPV? Next slide, please. So, essentially, you have kind of the same PV  panels you would be using for land-based system   but – so floating solar is an application of the  existing PV technology and you have the panels   sited on a floating device, whether it's a float  or a pontoon. So, if you look at the figure on   the top, it shows kind of an example float. Then  you have this located on different kinds of water   bodies, whether it's lakes, ponds, or reservoirs.  Then you have mooring lines providing stability.   Then this system is connected to transmission.  Then it can serve or meet demand on the grid.

There's two main types we're seeing. There's this  kind of more standalone system. Then we're seeing   the more hybrid system increasingly in different  parts of the world, but we're seeing some initial   deployments in Southeast Asia specifically.  In this type, you're pairing the FPV system   with a hydropower system. This specific kind of  hybrid type is of interest for many reasons, but  

I will highlight two key reasons why we're  seeing interest in this technology. Next. So, overall, there's several  benefits of FPV, as I noted,   but the key one, irrespective of whether it's a  standalone system or a hybrid system is around   reduced land use. So, utility scale PV  deployment requires lots of land. So,   countries that have land constraints  because of just limited land available,   but also the land pressures because of the need to  meet other priorities, whether it's agriculture,   housing, forestry, has really made land expensive  in a lot of countries in Asia. So, there's a lot   of excitement about the potential to scale RE  deployment to meet their growing energy needs   while preserving land for other uses and  kind of avoiding any land use conflicts. Then the rest of the co-benefits listed here.  There's several that I could have added here,  

but I'm just highlighting some of the  hybrid-specific benefits listed there.   Caitlyn kind of touched on this in detail, so I  won't go into too much detail. But essentially,   for the FPV system, hydropower  provides an opportunity for it to   essentially operate as a dispatchable resource,  which is of interest because of concerns around   the intermittency of the resource.  Then, for hydropower systems,   it's especially of interest because, in some  countries in Southeast Asia specifically that   might depend a lot on hydropower resources, there  are concerns during the dry seasons around threats   to energy security and providing reliable  electricity. So, the opportunity to really   supplement potential dips in hydropower operation  with outputs from PV plans is really attractive. So, going to the next slide, I'll just provide  an update on the current state of global FPV   deployment. So, currently, we're seeing that total  installed capacity is at about 2.6 gigawatts,  

up from 6 megawatts in 2013, which is still  quite small compared to kind of global solar   PV deployment. But this is just – this industry  is – there's a lot of opportunity for growth   because the estimated technical potential is about  seven terawatts. So, if you look at the figure   on the bottom left, we see that there's  been kind of consistent growth in the   last decade or so in the industry. The majority  of the installed capacity is located in Asia.

If we click next, we can see that most of that  deployment in Asia has been in China and a few   other countries shown there in the figure in  the bottom right, but we're seeing deployment   starting to expand view on the Asia region to  Europe and parts of Africa. So, when it comes to   system costs, on average, FPV systems are still  more expensive than land-based PV systems. But   just wanted to bear in mind that this is still an  emerging technology and cost expected to decline.   On the other hand, we have seen kind of a wide  range of system costs from about 500 to $3,000.00  

per kilowatt. These costs depend on a variety of  factors including kind of the country that the   system is sited in and the actually kind of water  body that the PV panels are sited on. In countries   that may have kind of turbulent rainfall or  typhoon season, for instance, there might be the   need for added infrastructure to make sure that  the FPV system is stable during those seasons.

So, if we go to the next slide, I'm not  going to quickly walk through the research   we did to explore the operational benefits  of hybridizing FPV with hydropower. So,   we essentially looked at three example systems.  So, this figure kind of just is a simplified   configuration of a hydro-only system where  the generation mix doesn't include any PV,   standalone system where the FPV – you have  FPV in the system, but it's really operating   independently of any other generation, and then  you have the full hybrid systems. Thinking back   to what Caitlyn said, here you have the FPV  essentially hybridized, with a hydropower plant   in this case. The key difference here is that  they share an interconnection. So, essentially,   when you're optimizing their operation, there will  have to be kind of – yeah, so the – you would have   to pick when and how you're using the PV plant as  opposed to the hydropower plant, in some cases.

So, if we go to the next slide, we explored  this research question using the Engage model,   which is a web-based platform that  enables multi-energy-sectoral planning.   It allowed us to do some production cost modeling  for these very small model systems. Here,   I'm just quickly showing kind of some  of the example results you could get.   So, if you want more information about the  tool, you can go to the link, but essentially,   we're looking at the dispatch for one week during  the year. This is the first week of generay.   On the bottom of that figure, the colors  that correspond to different nodes. So,   in dark blue is the hydropower plant. In  yellow is the PV. In orange, you have the  

coal-powered plant. Then the turquoise color is  just the reservoir serving the hydropower plant. If we go to the next slide, just highlighting  some more of our findings. Essentially,   what you see here is on the X axis is time. So,  that's generated through December 2019. On the Y   axis is PV generation and megawatt-hour. Then the  different lines correspond to the diff scenarios.  

So, the solid line is the FPV standalone  system. Then kind of the dashed line there   corresponds to the full hybrid system. You're  not seeing the hydro-only system here because,   as I had mentioned, the hydro-only system that we  modeled didn't have any PV in the generation mix.   I just want to highlight the differences in PV  generation here. We're seeing that in the hybrid  

system, we are seeing consistently higher  PV generation throughout the year. Sorry. So, next figure. Here, also, just kind of showing  the corresponding hydropower generation during the   whole year as well. So, again, on the X axis  is time. Y axis is the hydropower generation   and megawatt-hour. Here, again, we're seeing  differences in hydropower generation. So, here,  

you actually do see all the three scenarios. So,  again, in solid blue is the FPV standalone system.   Kind of your dotted lines, you have the hydro-only  system. Then, in your dashed-dotted lines,   you have the full hybrid system. We  see that in that hydro-only system,   you're really using a lot of the hydropower plant  during kind of August to September timeframe. Then, based on kind of the data you're using,  later on in the year is when they typically   have the dry season, and you see a drastic decline  in hydropower plant operation. But when you have   the FPV as an option, and then when you  even have a fully hybridized, we see that   the system chooses to optimize and actually  use less of the hydropower resources during   the late summer months and, instead, uses  more of that during the dry season. So,  

it's essentially conserving water resources  for use later in the year. So, next slide. Here, you see kind of similar figures. I just  wanted to highlight the complementarity of these   resources. So, Caitlyn mentioned that a key  motivation for hybrid deployment is that some   of these resources really complement each other.  So, if we click through the rest of the slide,   we see that. This is just showing one month as  opposed to the whole year. So, again, on the X  

axis is time. Y axis is PV generation on the top  and hydropower generation on the bottom figure. If we click through one more time, we can see  that whenever you see increases in PV generation,   you have them complementing each other with a  decrease, corresponding decrease in hydropower   generation. So, the system is optimizing  when to run PV generation versus running   hydropower plants. We see that lasting, looking  at the bottom figure, looking at the hydro-only   scenario. We see that just consistently keeps  operating. But once you have FPV as an option,  

once you even fully hybridize, it really allows  you to conserve water resources during this month. So, kind of to wrap up my presentation, our  modeling results indicate that hybridizing FPV   with hydropower could reduce PV curtailment. So,  it could increase the value of the FPV asset. It   can also conserve water resources. So, in places  that kind of have concerns about depending   on hydropower too much, especially during dry  seasons, hybridizing with FPV could provide an   opportunity to really conserve water resources.  Overall, just wrapping up this presentation,   FPV is still an emerging PV technology. There's a  lot of excitement and interest in the technology  

for several reasons that I've highlighted  earlier. But there's a lot that needs to be   kind of learned about the value that it could  provide to the grid and to plant owners.   Thank you. I'll hand it over to,  I believe, Sarah at this point.

>>Sarah: Thank you so much, Sika. Thanks, Sika  and Caitlyn, for those _____ presentations.   Now we have some time for questions. I had a  question actually for Caitlyn. Do you need to have   prior experience in your country on renewables  and storage in order to procure a hybrid project? >>Caitlyn: I certainly wouldn’t say you need it.  Of course, it would help because the hybrid is   just simply – it's combining those two resources  together. So, having some experience, I think,   is helpful. But at the same time, deploying them  together really helps avoid some of the challenges   that we've struggled with over the recent years  to integrate more and more variable renewables,   for example. So, it wouldn’t hurt but, definitely,  it's not necessary since we can design these  

projects in a way to mimic more conventional power  sources but using these cleaner resources that end   by combining sort of the low-cost nature of  one but with the dispatchability of the other. >>Sarah: Thanks, Caitlyn. I mean, is  operating a hybrid power project more   challenging from a grid operations point of view? >>Caitlyn: I would say it depends  on how it's built and also   how the plant owner decides to operate it. So,  in theory, these resources can be dispatched in   the same way that independent projects could be  if they're responding to the same grid signals.   We would expect them to be operated in a pretty  similar way and in a way that is very grid   friendly. You want to meet those periods  of high stress and you want to conserve and  

hold back your energy during those periods where  there's a lot of low-cost generation available,   because that's not good for you and it's  not good for the grid either. That sort of   indicates that there's already  enough supply available. So,   it's better to shift that production into  a period of higher stress later in the day. I think we're also developing these  technologies in a way that they're   somewhat out of the box. You can just deploy them  with a control system that helps you optimize the   system without needing to know how to control each  one individually. They're designed to respond to  

the signal and provide the benefits that the  grid wants in a way that doesn't introduce a lot   of complexity to the plant owner and the plant  operator. But I wouldn’t – more than anything,   I think the more complex thing is building them  in the right way and designing them in a way that   maximize value, both to the plant owner and to the  grid. But once that's in place, I think operating   them would be very similar to other independent  projects and also other power plant types. >>Sarah: Thanks, Caitlyn. We have a question  from Rogueness. For fossil and storage,  

what is stored, the energy or the fossil fuel? >>Caitlyn: So, a not huge but somewhat growing  application in the United States is to add a   battery technology to the fossil power plants so  that the battery can respond to quick response   signals and it can help avoid ramping your fossil  fuel power plant in a way that is damaging to   its mechanical pieces. So, basically, the battery  is meant to help you avoid otherwise induced   operations and maintenance costs. In general,  these tend to be terribly small batteries coupled   with a much larger fossil fuel power plant. But  it is – it's the electricity that's being stored,   either diverted from the power plant generation  itself, which can also help with ramping,   or stored from the grid. In either case, the  real purpose is to avoid having to respond to   any quick response signals from your fossil power  plant because your mechanical pieces just don't   really like doing that. So, the battery can absorb  that and try to avoid some induced cost otherwise.   So, yeah, the short answer is that it's storing  electricity, not fossil fuel, in that case.

>>Sarah: Thanks. We have a question  from Ryan. What is the capital cost of   four-hour generation batteries? So, those  estimates range from 1,200 to $1,500.00   per kilowatt for a 4-hour battery.  But maybe the operative question is,  

"Why are lithium-ion battery systems  more viable than other technology types?" >>Caitlyn: Than other storage batteries that are – [Crosstalk] >>Sarah: Than other battery types – yeah,  than other battery storage technology types. >>Caitlyn: Yeah, I mean I think it's partially  price, but it's also partially that we have the   manufacturing plant set up for the lithium-ion.  We're producing those at a much higher volume   than other battery technologies. So, they've just  come a little bit further down the learning curve.   I wouldn't say lithium-ion is guaranteed as the  future for hybrid in any sense. We tend to include  

them in today's deployments because that's what  we're seeing people building, for the most part. But in the future, really what we  care about in our modeling anyway,   is just voucher efficiency and the cost. We do  assume that, at some point, there could be a   transition in the chemistry for the batteries  that are used. We're not capturing exactly what   that is or when it happens. But just that  lithium-ion batteries can't keep getting  

cheaper forever. At some point, they plateau,  and another technology would have to come in.   So, I do think that that's one of the more  common chemistries being used in projects today,   but I don't necessarily think that it's the  only one to be considered in the future. >>Sarah: Thanks. We kind of have similar  questions around PPAs. So, basically,   are PPAs right now, renewable energy PPAs, are  they engineered to take on the hybridization?   That's really across all technologies.  We had questions about hydropower, FPV,   renewable plus storage. I think maybe that  would – Caitlyn, that would be for you.

>>Caitlyn: Yeah, I think it's an evolving space.   Clearly, we have examples of PPA structures that  are able to accommodate the hybrid technology   fairly easily. It ultimately just depends on  what the hybrid is being designed to do and   how different that is from separate projects.  So, clearly, we can absorb a battery technology   and compensate it just for the energy output  in the same way that we would a PV generator. In this case, all we're doing is augmenting how  much we're producing because we had that battery   there to either take in curtailed energy or  take in periods of really high radiance and   lower demand and shift it to another time. That  sort of easily compensatable within existing   PPA structures. But if hybrids evolve more to be  there as a firm capacity resource, for example,  

I think PPAs are still able to accommodate them,  but it will require a shift. We'll ask to be   modifying our PPAs so that the battery  is compensated in a very specific way. We are seeing that happening in the United States  today. We have a very specific and sort of famous   example in Arizona where the battery is only being  compensated at very specific times of the year   because that's what they needed it to do.  They needed to have a firm resource available   under the very, very high demand  periods in the summertime,   and basically the entire annual compensation  happens in a couple of hours in the summer.  

So, it might take some innovation, but I don't  think there's anything about a hybrid that's   so different that we can't leverage the  techniques we're already using today for   separate PV and battery projects, and,  in the future, other resources as well. >>Sarah: Thanks, Caitlyn. We have a couple of  pretty specific questions about floating solar for   Sika. So, one is, "Is floating solar only viable  in reservoirs, or can you site it in the tail   race, too?" I think that's below a dam. Then, "Do  you have any successful examples of floating PV   in sea water, like salty water?" So, I don't know  – those are really specific – if you know this.

>>Sika: Uh-huh. Yeah, I can give a little bit of  insight into that. So, kind of what I presented is   there's several kinds of designs of FPV systems  coming online. But what we've seen at the moment   is predominantly kind of FPV sited in reservoirs.  But the space is really kind of expanding into   looking at near-share and off-shore, and even  beyond at official water bodies. So, to the   second question, there have been installations on  salty water and even installations on water bodies   that are otherwise unusable. So, in China, we've  seen installations on kind of polluted coal mines,  

for example. So, it's not necessarily exclusive  to reservoirs. The thing with reservoirs, though,   is that if you do have a nearby hydropower plant,  it offers the opportunity for hybridization. To the tail race question, I think there have been  a few feasibility studies, but we haven't seen as   much deployment there. So, the thing with FPV is,  essentially, a lot of the initial deployment has   been encouraged through government-funded research  and support. So, we're seeing a lot of pilot-scale   projects, and those were the ones that kind of  then moved – a lot of the pilot-scale projects   focused on FPV systems sited in reservoirs.  So, now, support is also expanding to   looking at alternative hosting water bodies. So,  in the future, we may see kind of installations  

on different kinds of water bodies, but  definitely not exclusive to just reservoirs. >>Sarah: Then another question on the  environmental impacts. So, are there   any concerns about biodiversity or  fisheries or – with floating solar? >>Sika: So, the research in that is  still ongoing. So, at this point,  

it's a bit inconclusive. We actually conducted  some research last year looking at the potential   environmental – we didn't conduct it ourself.  We reviewed the research in this space.   It's still unclear on whether FPV system improve  water quality, affect aquaculture, or there's   kind of a negligible impact, or a negative impact,  even. So, research is still ongoing in that space. >>Sarah: Yeah, definitely something to monitor.   Then what governs the use of the storage system  for ancillary services or for energy purposes?   Thanks to Tom, for your question. Is it in  the PPA or the interconnection agreement? >>Caitlyn: It would be more in the PPA, and it  would be more in, I would say, in the design   of the system as well which,  again, it feeds into the PPA.  

But ultimately, the provision of ancillary  services is relatively modest in terms of   your interconnection use. You're not sending a  lot of energy that way. But you would want to   design your system in a very different way,  because you don't want to 4-hour battery to be   able to provide a 30-second service. That would be  a waste of sort of your investment in that case.   So, I'd say it mostly comes into  play in the design of the system,   which of course will then influence what your PPA  looks like and the compensation for it as well. >>Sarah: So, we're getting near the end of our  time. So, I think maybe we'll just close with   a question which is, "What circumstances should  utilities and regulators consider hybrid projects   and how should they determine which  combination is best suited for their grid?" >>Caitlyn: Hybrid projects, I don't think there's  a situation where they shouldn’t be considered.   If you're able to do it at lower cost,  then you're able to make all of your   individual access more controllable. That's  a win for everybody. The plant owner now  

has more confidence in their investment.  It's a lower-risk investment because you   know you can shift and sort of accommodate  changes in market prices and structures.   From the utility's perspective, it eases  the burden a little bit of trying to   optimize a suite or resources where the _____  _____ again share a ______ variable, for example. In terms of how you design the one that's most  optimal, I think it really depends on what your   resources are that's available. I think that's  the primary driver. Then the second one is sort   of how your net load duration could have  evolved. So, as you get more and more PV,  

of course PV/battery is going to make  more sense because adding more PV to   the middle of the day when you've already  met all your load is no longer beneficial.   If you're in a high-wind region, I think those  are the places where we're seeing a move towards   hybridization as well, because you're already  saturating those times when wind is producing.   So, I think it's mostly driven by your resource  strengths in your region. But then, secondarily,  

based on how much you've already kind of  traded your grid with these variable resources. >>Sarah: Thanks a lot, Caitlyn, and Sika, for  your presentations. Thank you so much to our   participants for their awesome questions. A  recording of the webinar and the slide deck   will be emailed to attendees when we're done  here. You can also find other recordings on  

the USAID/NREL partnership learning channel.  So, stay tuned for our next webinar. Follow   NREL on Linked In or Twitter. Have a great  rest of your day. Thank you, everybody.

2021-05-19 17:34

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