Nov 16, 2016

Mobile solar: the sky's the limit

3 min
In late June, a solar-powered drone developed by Facebook took to the skies for a 96 minute test flight. The aircraft, called Aquila, might have the...

In late June, a solar-powered drone developed by Facebook took to the skies for a 96 minute test flight. The aircraft, called Aquila, might have the wingspan of a jet airliner, but it isn’t designed for commercial passenger flight. The minds behind the world’s most popular social network have an entirely different plan for their unmanned aerial vehicle (UAV): ‘beaming’ internet signals to communities in remote locations.

With Google also carrying out internet-delivery drone trials early this year, it’s clear that tech giants feels unmanned aircraft are part of the industry’s future. Facebook is still assessing whether Aquila will be an efficient and effective alternative to simply installing network infrastructure in unconnected regions. However, this doesn’t mean that other developers are waiting for a big name to prove the technology is viable before moving into the market.

The many uses of a solar drone

“Right now, it certainly seems like unmanned aircraft are a ‘no-brainer’. It’s going to happen and it has the potential to be quite big,” says Rich Kapusta, Chief Marketing Officer and Head of Sales at Alta Devices, a California company which specialises in delivering the world’s most thin and efficient mobile solar technologies. This year, the company broke the world record for dual-junction solar cell efficiency and currently holds the record with 31.6 percent of sunlight converted into electricity by its gallium arsenide (GaAs) cell.

Alta Devices is currently in the midst of exploring the applications of its ultra-thin and efficient solar cells. And it’s putting significant stock in the UAV market.

“If you believe what Facebook and Google are saying about how many planes are gonna be needed to cover certain pieces of the globe to provide communications services, the numbers are in the tens of thousands of airplanes,” Kapusta says. “We are talking to all the manufacturers that make those kinds of aircraft.”

While large solar drones have potential in the telecommunications sphere, Alta believes that a different market for smaller unmanned aircraft will soon develop. A small solar UAV won’t fly for months at a time, but will spend days or hours monitoring large agricultural assets or carrying out remote search and rescue operations. When the wings of these aircraft are covered in Alta’s solar cells, Kapusta predicts that they will be able to stay aloft for perhaps 9 or 10 hours at a time.

Do we have the technology?

If solar drones, big or small, are going to be flying to every corner of the globe, they will inevitably encounter regions with short days or very low sunlight. This will present hardware challenges and require more efficient solar cells and greater battery storage capacity.

“You can imagine a government that might want to do surveillance over the polar ice caps,” Kapusta explains. “They’re going to spend a lot of money making that happen, and that market may be small, but there is going to be a need for higher performance solar cells.”

Developers worldwide are approaching the theoretical limit for solar cell efficiency, particularly those using crystalline silicon, the most common PV manufacturing material. Other compounds, including gallium arsenide — Alta’s material of choice — have greater efficiency potential. Adding multiple junctions, or layers, to a single cell can also improve its efficiency. Supplementary layers can be optimised to convert certain pieces of the sun’s spectrum into electricity, thereby increasing performance. However, the more complex the solar cell the more expensive it will be to produce and eventually purchase.   

“We’re trying to make our single junction as cheap as possible and then create a few technologies that give higher performance at higher cost points for those people that really need the extra performance,” says Kapusta of Alta’s attempts to reconcile cost and energy output.

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Apr 23, 2021

Drax advances biomass strategy with Pinnacle acquisition

Dominic Ellis
2 min
Drax is advancing biomass following Pinnacle acquisition it reported in a trading update

Drax' recently completed acquisition of Pinnacle more than doubles its sustainable biomass production capacity and significantly reduces its cost of production, it reported in a trading update.

The Group’s enlarged supply chain will have access to 4.9 million tonnes of operational capacity from 2022. Of this total, 2.9 million tonnes are available for Drax’s self-supply requirements in 2022, which will rise to 3.4 million tonnes in 2027.

The £424 million acquisition of the Canadian biomass pellet producer supports Drax' ambition to be carbon negative by 2030, using bioenergy with carbon capture and storage (BECCS) and will make a "significant contribution" in the UK cutting emissions by 78% by 2035 (click here).

Drax CEO Will Gardiner said its Q1 performance had been "robust", supported by the sale of Drax Generation Enterprise, which holds four CCGT power stations, to VPI Generation.

This summer Drax will undertake maintenance on its CfD(2) biomass unit, including a high-pressure turbine upgrade to reduce maintenance costs and improve thermal efficiency, contributing to lower generation costs for Drax Power Station.

In March, Drax secured Capacity Market agreements for its hydro and pumped storage assets worth around £10 million for delivery October 2024-September 2025.

The limitations on BECCS are not technology but supply, with every gigatonne of CO2 stored per year requiring approximately 30-40 million hectares of BECCS feedstock, according to the Global CCS Institute. Nonetheless, BECCS should be seen as an essential complement to the required, wide-scale deployment of CCS to meet climate change targets, it concludes.

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