Will tech giants follow Tesla into energy storage?

Tesla Apple and Google: investments suggest these might be the companies dominating the energy storage market of the future.

Tesla Apple and Google: investments suggest these might be the companies dominating the energy storage market of the future. Photo credit: Apple Inc

By Jason Deign 

Tesla’s early success in the energy storage market is raising questions over whether nearby Silicon Valley firms might follow suit. Apple and Google are just two consumer technology giants that could make a play for the sector.

Apple, whose 1 Infinite Loop HQ is just 20 minutes’ drive from Tesla’s Freemont offices, has long been the subject of energy storage speculation. In 2011 the company filed a patent for a novel wind energy storage system.

The system was designed by Jean Lee of Apple’s Environmental Technologies Department, who has also investigated the use of hydrogen fuel cells for laptop power.

It “uses a set of rotating blades to convert rotational energy from a wind turbine into heat in a low-heat-capacity fluid,” according to the patent application.

“Next, the system selectively transfers the heat from the low-heat-capacity fluid to a working fluid. Finally, the system uses the transferred heat in the working fluid to generate electricity.”
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Study points to PCM breakthrough

Research from TermoFluids and the Tesconsol consortium may provide a breakthrough in the use of phase-change material for thermal energy storage in concentrated solar power plants. Photo credit: KIC InnoEnergy

Research from TermoFluids and the Tesconsol consortium may result in the breakthrough of phase-change material for thermal energy storage in CSP plants. Photo: KIC InnoEnergy

The case for using phase-change materials (PCMs) for thermal energy storage is being bolstered through research using a modelling technique out this year.

The technique, developed by a team in Catalonia, Spain, has uncovered a PCM tank approach that could theoretically allow up to 74% of stored thermal energy to be returned from storage.

It might also reduce the amount of storage material needed in solar thermal plants by 32% compared to traditional two-tank molten salt systems, CSP Today reports.

The approach, called multi-layered solid PCM (MLSPCM), works by using two PCM layers separated vertically by a layer of filler materials such as cheap, readily available granite or quartzite.

The filler keeps the top and bottom PCM layers close to their optimum discharging and charging temperatures, respectively. Overall, the amount of PCM material needed would be much less than in a PCM-only setup, which should help reduce costs.

And since each PCM layer is kept close to its optimum charge or discharge temperature, the efficiency of the system is increased.
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Solar thermal energy storage loses its way

Does phase-change material storage have advantages over molten salt thermal energy storage for a concentrated solar power plant? Photo credit: Crescent Dunes Solar Energy Project, SolarReserve

Is phase-change material storage better than molten salt thermal energy storage for a concentrated solar power plant? Photo: Crescent Dunes Solar Energy Project, SolarReserve

Too much salt is not just bad for your health. It could also harm the likelihood of thermal energy storage (TES) cost reduction across the entire concentrated solar power (CSP) industry.

Right now, molten salt TES is seen as critical in justifying the high cost of CSP versus other renewable energy sources, such as solar PV or wind.

TES allows CSP, or solar thermal energy, to deliver stable, round-the-clock power, which is more valuable to grid operators than the intermittent generation provided by renewable alternatives.

But it is just possible that a growing preference for molten salt among CSP developers could hamper the chances of adopting more efficient and cost-effective types of TES.
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The tricky art of storing heat from the sun

The poster boy for concentrated solar power with thermal energy storage is Torresol Energy’s 19.9MW Gemasolar power plant in Andalusia, Spain. Photo credit: SENER

The poster boy for concentrated solar power with thermal energy storage is Torresol Energy’s 19.9MW Gemasolar power plant in Andalusia, Spain. Photo credit: SENER

A Chilean renewable energy tender that closed in October could be the first in the world where energy storage becomes the deciding factor for success. Great news for the industry? Perhaps. But actually it’s not so easy to say.

The bidding for a concentrated solar power (CSP) plant in Chile’s Atacama Desert, backed by a USD$20m government grant and more than $86m in alternative funding, is conditional on a minimum three-hour thermal energy storage (TES) facility.

And sources close to the tender, the entries for which are still being considered by the Chilean government, have confirmed that if there is a tie between different offers on all the main eligibility criteria then the amount of storage will determine which project wins. This might sound unusual, but in CSP it’s not something that would raise eyebrows.

After all, CSP players have increasingly been embracing storage in recent years. For those new to the subject, CSP involves focusing sunlight onto a point to create enough heat to drive a turbine. The critical word here is ‘heat’: unlike photovoltaics (PV), CSP does not produce electricity directly from sunlight. That means it can only be used in areas with high solar irradiation. It’s also generally more expensive than PV.
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Energy storage news: 11.12.13

China is to build a concentrated solar power (CSP) plant with a thermal energy storage system in Delingha, the province of Qinghai. Qinghai already contains more than 60% of the Chinese solar photovoltaic installed capacity. Photo credit: SSE

China is to build its first concentrated solar power (CSP) plant with thermal energy storage system in Delingha, in Qinghai. Qinghai already has over 60% of the Chinese solar photovoltaic installed capacity. Photo credit: SSE

The top energy storage news stories from our Twitter feed over the last week.

  • The UK Department of Energy and Climate Change has awarded a GBP£3m contract to EValu8 Transport Innovations, on behalf of the Electric Vehicle Embedded Renewable Energy Storage and Transmission (EVEREST) Consortium. EVEREST is developing modular energy storage systems based on recycled electric vehicle batteries.

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US funds thermochemical storage research

In a move that may have implications for the current trend towards molten salt storage in concentrated solar power (CSP), the US Department of Energy (DoE) has announced a new funding opportunity for thermal energy storage.

The ‘Efficiently Leveraging Equilibrium Mechanisms for Engineering New Thermochemical Storage (CSP: ELEMENTS)’ programme will award USD$20 million to up to 24 projects for research and develop into thermochemical energy storage systems (TCES) to be applied to CSP technology.

As the DoE points out, TCES technologies have the potential to store energy at densities over 23 times greater than that of existing sensible energy storage technologies, principally molten salt. There are a number of preconditions if you’re interested in the funding, however. Any TCES considered will need a minimum of six hours of thermal storage, to be used in utility-scale CSP plants.

Additionally, the TCES system must validate a cost below $15 per kWh-thermal and should operate at temperatures above 650ºC. So the DoE is sensibly trying to both raise temperatures and lower costs in CSP TCES, with the eventual goal of providing a levelised cost of energy of $0.06 per kWh, without subsidies.

The benefits of energy storage for CSP

Guest article by Jack Ahearne of CSP Today. 

The modern age of concentrating solar power (CSP) can arguably be traced back to the 354MW Solar Energy Generating Systems (SEGS) in the Mojave desert, which now make up the oldest operating plant in the world, as well as one of the largest. However, recent developments in the industry will see SEGS eclipsed by five projects that are scheduled to come online in 2013-14, with a combined total of 1.3GW.

The five plants in question are Abengoa’s Solana and Mojave projects, BrightSource Energy’s Ivanpah Solar Electric Generating System and finally the Crescent Dunes and Genesis plants being developed by SolarReserve and NextEra Energy Resources, respectively.

Recent commentary on the industry agrees that this increase in operating capacity, as well as 1.5GW of projects in planning in the US, demonstrates the strong support for CSP in this region. And there are a number of reasons why it makes sense for the US to pursue leadership in CSP development for years to come. Firstly, the US has ample high irradiation suitable for CSP development, particularly in California, Arizona and Nevada.

Secondly, there are significant economic benefits. The prime materials for CSP plant construction are readily available in the US, in addition to projects generating local employment, particularly during the construction phase of a plant. But most importantly there are a number of reasons why utilities, CSP’s ultimate customers, and grid operators might welcome the technology.

As utilities are increasingly being required to introduce renewable portfolio standards, many of the options available, such as wind and solar photovoltaic (PV) plants, are challenging because of their output variability. Therefore as PV and wind integration increases, the thermal energy storage capability of CSP becomes a significant feature that will drive projects forward for years to come.

CSP with storage can modify ramp rates, keeping them more in line with grid requirements, because plant operators have the flexibility to stop putting solar energy into the grid at a given time, or if needed, put more power into the grid. To explain the benefits that CSP and thermal energy storage can offer grid operators and utilities, CSP Today has released a free guide to CSP’s role in the US energy mix.

This guide provides data, information and interviews on how CSP and its storage technology can help utilities and grid operators overcome PV and wind intermittency, and gives an introduction to the current thermal energy storage technologies operating in plants. Read it now.

Thermal energy storage key to CSP

Thermal energy storage is playing an increasingly important role in the commercialisation of concentrated solar power (CSP), according to our media partner CSP Today.

In a recent interview Kristin Hunter, spokesperson for BrightSource Energy, developers of the Ivanpah Solar Electric Generating System, explained to CSP Today that “as energy storage is added to plants, solar thermal becomes even more valuable because stored energy can be used to accommodate the variability of other non-dispatchable renewables, including wind and PV.”

In addition, CSP with storage can modify ramp rates, keeping them more in line with grid requirements, because plant operators have the flexibility to stop putting solar energy into the grid at a given time, or if needed, put more power into the grid.

Because the addition of thermal energy storage involves additional capital costs for a project, the current perception is that this cost is too high when compared to technologies such as wind and PV.

However, in a recent interview with CSP Today, Tex Wilkins, executive director of the CSP Alliance, explained that “going forward, storage will not add anything to ratepayers’ cost. It can actually decrease the cost. What happens is you are able to better use the turbine, the generator and all the power block because you are using it for more hours of the day.”

To explain the benefits that CSP and thermal energy storage can offer grid operators and utilities, CSP Today has released a guide to CSP’s role in the US energy mix. This guide provides data, information and interviews on how CSP and its storage technology can help utilities and grid operators overcome PV and wind intermittency.