From faster and better drug design to solving the travelling salesman problem at the scale of global supply chains, quantum computers are raising hopes that today's most complex problems, most of which are impossible to solve with existing technologies, could one day be cracked – in minutes.
It seems natural, therefore, that experts in the field would increasingly turn their attention to whether quantum computers could provide solutions to one of the greatest challenges of our time: climate change.
Unlike the classical computers that we are most familiar with, quantum computers are built to leverage the strange laws of quantum physics. Engineers are still figuring out how to do this on a large scale, meaning that quantum computers, for now, are of limited use; but it is expected that when a fully-fledged device is built, it will come with exponential compute power and will be able to rapidly solve problems that would otherwise require impossible amounts of time and computing resources, even for the most powerful supercomputers.
As noted by Q4Climate, an organization that gathers experts at the intersection of quantum research and climate sciences, the field of research applying itself to finding out how quantum computers could help fight climate change is currently almost non-existent.
But things are slowly changing. For example, leading quantum software company Zapata Computing has established that the technology could have an impact on various goals outlined by the United Nations for sustainable development, ranging from clean water and sanitation to affordable and clean energy.
Q4Climate has also put together a report which discusses some areas where quantum computers could make a big difference.
There is a caveat. Quantum computing is a nascent technology – one that hasn't even accomplished any useful calculation yet – and as such, any assessment of its future capabilities has to be put into perspective.
"Q4Climate is not saying that quantum computing will solve the climate change problem," Alexandre Blais, who sits on Q4Climate's advisory board, tells ZDNet. "All we are saying is that as scientists, we need to pay attention and see if we can help. At this stage, we are only pointing out interesting areas of research and hoping that experts in these areas will take on the challenge."
Take quantum simulation, which consists of predicting the behavior of a system made up of molecules – a particularly difficult problem to solve for a classical computer, due to the many factors that can influence the way that molecules can interact with each other.
Many companies are investigating how quantum computing could improve the simulation of new drugs or of next-generation materials. But quantum simulation could also help to create more efficient batteries, better materials for solar cells or wind turbines, or even more absorbent catalysts for carbon-capture technologies.
In agriculture, quantum simulation could dramatically reduce the power that is needed to manufacture fertilizers, which represent up to 2% of global energy.
"Doing quantum chemistry on a quantum computer remains challenging, but it has been studied thoroughly and we know there are speedups that we can expect once we have a quantum computer," says Blais. "We can expect a quantum computer to find new ways to create fertilizers. Imagine if we were able to reduce the energy consumption even by a fraction of a percent, that would be a massive gain on a global scale."
Quantum computers are also expected to excel at difficult optimization tasks, which Q4Climate has also identified as an area of interest. Grid optimization problems could lead to power and energy savings, for example, while better management of traffic flows could reduce carbon emissions.
The technology could also optimize the design of carbon-intensive materials. For example, according to Boston Consulting Group (BCG), lighter, stronger and better insulating materials that require less carbon to produce could reduce emissions from buildings, transportation, or the production of metals such as cement.
Quantum computers, therefore, could be a key tool in designing solutions for climate change – but they could also be useful for the environment regardless of those promising applications.
Whether it is used for climate-related calculations or not, the technology is expected to generate phenomenal gains in computational speed, which means that less resources will be required to run even the most complex programs.
The workloads that are currently run on classical computers are notoriously energy-intensive and are only expected to consume more resources as they grow. "When it comes to AI, a training job can consume the carbon footprint equivalent of five cars throughout its lifecycle. That's huge," Tamar Eilam, an IBM fellow who is currently researching ways to reduce the impact of cloud computing, tells ZDNet.
Research shows that the highest-scoring deep-learning models are also the most computationally-hungry, due to their huge consumption of data. One algorithm's lifecycle was found to produce the equivalent of 284,000 kilograms of carbon dioxide, which is effectively nearly five times as much as the lifetime emissions of the average American car, including the manufacturing process.
In simple terms, a quantum computer that carries out calculations faster could slash those numbers. "Because it takes a much shorter time to do the computation, it will also be much more efficient in terms of energy," says Eilam. "For a given computation, if you can solve it faster with a quantum computer, it goes into the equation of calculating how much energy you're consuming."
Of course, the equation comes with many other factors: for example, quantum computers such as those developed by Google and IBM, which are known as superconducting quantum computers, have strict cooling requirements and need to be kept at temperatures colder than outer space.
But early research in this space seems to indicate that the overall energy consumption of quantum computers will be lower than that of classical devices. D-Wave's 2000Q quantum annealer, for example, was found to consume four orders of magnitude less power than IBM's Summit supercomputer, which is one of the most powerful classical devices in the world.
Similarly, scientists from Oak Ridge National Laboratory have calculated that quantum computers have the potential to reduce energy usage by more than one million kilowatt hours.
There is still much research to be done before those numbers can be confirmed by real-life usage of the technology. As quantum computers increase in size, more parameters will play a role in determining the devices' environmental footprint, ranging from water consumption to the use of renewable materials in chip fabrication.
But even as a scientist that comes from outside of quantum computing, Eilam has high hopes for the potential that quantum computers hold to reduce the environmental impact of the digital world.
"I am not an expert in quantum computing but I'm in the area of sustainability and quantum computing is genuinely a solution we are investigating," says Eilam. "We shouldn't place our bets on one technology, but we absolutely should look at multiple different avenues and take some risks in exploring these avenues."
In this case, the most significant risk stems from the timeline: it may be a decade before quantum computing starts delivering on its promises, if it delivers at all. This seems too long given the urgency of the climate challenge.
Quantum scientists are aware of this, and few would defend the idea that quantum computing is the ultimate solution to climate change. Rather, the technology is seen as a possible tool to help environmental efforts in the long run.
"Climate change is unfortunately a long-term problem," says Blais. "If we take action now, we will still have to be paying attention to this problem in 10, 20, 40 years. Those are the timescales we are looking at."
The immediate focus, therefore, is to ramp up efforts to build large-scale quantum computers that can run useful algorithms – a goal that governments and companies are heavily investing in, and where there is no shortage of activity.
The next stage, however, and possibly the harder one, will be to incentivize quantum research groups to apply their efforts to climate-focused use cases for quantum computers. The potential exists, and the results could be game-changing. Making them a reality, however, could be easier said than done.