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Lightsail Energy

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LightSail Energy were a Berkeley, California-based company which aimed to introduce small, portable Compressed Air Energy Storage (CAES) systems to a wider market.


LightSail Energy

With the continuing growth of renewables, energy storage technologies have become of great interest to investors, and LightSail Energy were initially among one the main beneficiaries of this growing trend. Founded in 2008 in the Californian university town of Berkeley by Steve Crane and Danielle Fong, the Bay Area firm initially looked at ways to power electric scooters by using compressed air energy storage but quickly realised the potential of using CAES systems for larger scale energy storage projects.

The Role of Energy Storage Systems

A recurring problem in managing the production and distribution of electricity to meet consumer needs is that demand varies considerably over time. This can happen over the course of a single day, with demand being higher in the early evening than the early morning, and can also occur seasonally according to climatic and other conditions, with electrical demand rising during summer heatwaves due to the need for air conditioning or, in temperate climates, during winter due to the additional need for heating and lighting.

As a consequence of the global drive towards reduction of carbon emissions and the increased use of renewables such as wind or solar power, these varying levels of demand can create additional difficulties as the output from these new energy sources is intrinsically more erratic than that of traditional technologies such as coal-fired power stations.

Put simply, there is no guarantee that the wind will blow or the sun will shine during the times when the energy is most required. Temporary shortfalls can be made up by means of “peakers”, power plants, usually gas-powered, that come online at peak times. However, another commonly proposed, carbon-friendly solution is to develop energy storage technologies which allow energy to be “collected” at times of low demand and then “released” at peak times.

Compressed Air Energy Storage

The idea of using Compressed Air Energy Storage was not one unique to LightSail, but one that remains relatively uncommon in an energy storage sector that traditionally favours electrochemical solutions such as Lithium-Ion cells and other battery-based approaches.

Compressed Air Energy Storage systems operate on a totally different principle, storing energy by utilising the laws of thermodynamics and the behaviour of gasses when under pressure, particularly Boyle’s Law, the principle which states that the temperature of a gas rises as pressure increases and volume decreases.

CAES converts electrical energy into heat by using the energy input into the system to power a motor which in turn drives a compressor which raises the temperature of compressed air kept in a storage unit, the energy of which can then be reconverted back into electricity when required by the motion of the expanding air driving a generator.

CAES systems have generally been less popular because thermodynamic inefficiency means that much of the energy is lost through the radiation of waste heat.

LightSail Energy's approach to CAES systems

Previously, CAES systems have been typically employed in large underground storage units in order to capitalise on the economies of scale necessary to compensate for any inefficiencies in the process, something which makes them impractical for many uses.

The LightSail Energy storage system, however, takes an alternative approach by using smaller, more portable units built of carbon-fibre that can easily be transported in a shipping container, allowing the technology to be employed in a wider range of applications and making it more attractive to clients such as wind farm operators.

To maximise this versatility, compression/expander units and air storage tanks are placed in separate modules which can be scaled differently in order to better meet the needs of individual customers. Power units are claimed to have a generating capacity of 500 kw while the storage unit is claimed to have a 750 kw/h capacity.

LightSail’s stated goal was to revolutionise the energy industry by making the cleanest and most thermodynamically efficient CAES storage system possible, finally allowing a feasible manner of storing power from renewables until it was most needed on a scale large enough to be useful.

Current Status of LightSail Energy

In spite of their occasionally grandiose initial claims, LightSail Energy’s future is currently uncertain, with the company presently in “hibernation” according to senior executives. The attractiveness of the proposed technology lead to the firm achieving great investment success, raising over 80 million US dollars from investors who included many of the big names of Silicon Valley’s entrepreneurial elite, such as the Microsoft founder, billionaire Bill Gates.

However, the technical difficulties of delivering a commercially viable product led to the company running out of funding before its innovations could reach the market. Plans for a 2016 pilot project in Nova Scotia, Canada, a region noted for its wind farms, were also abandoned and their CAES system remains untested on a large, commercial scale. Staffing levels have been reputedly cut severely while the project remains dormant.

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