Deutsche Welle (English edition)
How many solar panels do we need to save the climate?
A zero-carbon-emissions energy system will rely mostly on low-cost solar electricity, experts say. About 100 giant solar panel factories must be built by 2025 for the world to defossilize its energy supply by 2035.
"We know the world needs to de-fossilize its energy systems," says Christian Breyer, professor of solar economics at LUT University in Lappeenranta, Finland, whose research group models transition pathways to future zero-emissions energy systems. "We need to get to net-zero greenhouse gas emissions — as quickly, safely, and cost-effectively as possible. To do that, we need technologically feasible, cost-optimized transition pathways for every region of the world. Our calculations show how we can do that."
Breyer's cost- optimized model of 2019 shows how a global energy system with net zero carbon emissions can be achieved. In the model, solar photovoltaics (PV) — solar panels — supply 69% of total global primary energy demand for all purposes. The rest comes from wind power, biomass and waste, hydropower, and geothermal power.
His zero-emissions scenario doesn't include nuclear power because it's "simply too expensive," Breyer told DW. "PV technology is becoming cheaper year by year; the construction costs of nuclear power plants, on the other hand, are rising." Moreover, it's much easier, faster, and less risky to install and operate solar power than nuclear power plants.
By when must the world stop burning fossil fuels?
The LUT researchers' solar power-based model raises two
questions.
First, by when must the globe reach net-zero emissions of greenhouse gases if we're going to meet the internationally agreed goal of keeping global warming below 1.5 degrees Celsius?
Second, how many solar power plants would need to be built — and by when — to meet solar energy's share of this climate goal?
DW asked Piers Forster, a climate scientist at the University of Leeds in the U.K., how much more CO2 can be cumulatively pumped into the air if the 1.5C degree target limit is to be met – without later having to make massive efforts to remove CO2 out of the air through expensive "geoengineering" or "carbon drawdown" measures.
His sobering answer: As of late 2020, to have a 2/3 probability of staying below 1.5C, we can release — at most — 200 billion additional tons of CO2 (GtCO2) into the air, beyond the 1,700 GtCO2 already released since the beginning of the industrial revolution.
In 2019 alone, emissions totalled about 40 GtCO2. If emissions stay roughly level for the next few years – which is very likely – the remaining CO2 emissions budget will be used up by the end of 2025. After that, the
world will be in "carbon overshoot," and on track toward very dangerous climate changes.
The implications? "We must get to zero emissions as soon as possible after 2025," says Breyer. "The current political target year for zero emissions is 2050. That's way too late."
The true cost of coal power There's already too much carbon in the atmosphere, and therefore much of the carbon being released into the atmosphere now will have to be taken back out in future to avoid dangerous climate changes and long-term sea level rise. That's going to be very expensive. It would be much cheaper to expand renewable energy systems more quickly and shut down coal-fired power plants sooner, Breyer says.
Here's why: Producing one MWh of coal-fired electricity causes about one metric ton of CO2 emissions, Breyer explains. Actively taking CO2 out of the air and permanently storing it may cost about €100 ($122) per ton in the long run. By comparison, one MWh of electricity cost an average of €33 on the electricity exchange in Germany in 2020.
This means coal-fired power is actually about four times more expensive than electricity from PV or wind power plants – or it would be, if the financial costs
of actively recapturing and storing each ton of carbon released from fossil fuels burning were included in the price of each MWh of coal-fired power, as economists have long recommended.
"This doesn't even include the health costs of heavy metal emissions from coal-fired power plants. In Germany alone, this pollution causes about 5,000 premature deaths every year, and in Asia, nearly a million," Breyer says.
The solution: build 100 giant PV factories immediately
A prosperous carbon-neutral global civilization with net-zero emissions will be 90% powered by electricity, the LUT model estimates – in part directly, in part via synthetic fuels (e-fuels). 69% of this electricity will come from solar PV. How many giant PV module factories will be needed to achieve that future?
It depends on how much we're willing to overshoot the world's remaining 200 GtCO2 carbon budget. Let's imagine a transition to a carbon-neutral world by 2035, and assume that the necessary new PV module factories will be in place by 2025, so they can get the job done within 10 years.
The world's largest PV module factory – by far – is currently under construction in China's Anhui province. It will have a production capacity of 60 GW per year, according to GCL System Integration. For comparison, global PV production capacity in 2020 was about 200 GW, 90% of it in China.
The LUT model envisions a global electricity system powered entirely by renewables, with 78,000 GW of installed generating capacity, including 63,400 GW of solar PV, about 8,800 GW of which will be in Europe.
Under current industry plans, by 2024, the cumulative amount of PV modules installed worldwide should reach nearly 1,500 GW, according to estimates from industry association SolarPower Europe. To achieve the LUT zero-emissions scenario by 2035, another 62,000 GW of PV modules (= 62 terawatts, TW) must be produced and installed between 2025 and 2035.
Existing plans foresee that PV factories totalling about 400 GW annual production capacity will be in place by 2024. If we want to install 62 TW of solar modules between 2025 and 2035, then by late 2024, we'll need to have built an additional 100 solar Gigafactories of 60 GW, each as big as the Anhui factory, for a combined 6000 GW annual production capacity. If Europe is to produce its own PV modules, 15 of those 100 giant factories must be built in Europe.
This aligns very well with Elon Musk's claim in 2016 that with about 100 PV Gigafactories, enough solar modules could be produced to power the world for all purposes.
What these numbers tell us is that a rapid expansion of renewable energy as the core element of a global race to net zero emissions is technologically feasible. After all, it's hardly impossible for humanity to build and operate 100 giant factories, 15 of them in Europe. The crucial question we face is: Will we finally take the warnings of climate scientists seriously, pick up our tools, and get the job done?