A remarkable 82 percent drop in the price of solar photovoltaic energy (PV) since 2010 has provided the world with a fighting chance to create a zero-emissions system that might be cheaper than the one it replaces.
According to the International Energy Agency, PV solar generating capacity will need to grow tenfold by 2040 in order to fulfill our dual task of reducing global poverty and limiting warming to well below 2C.
There are still critical challenges. Because solar is intermittent, as sunlight changes throughout the day and over the seasons, energy must be stored to ensure that it doesn't get too hot. It is also important to create policies that ensure solar energy reaches remote areas and the places it is most needed. There will always be trade-offs between solar power and other uses of the same land. These include conservation and biodiversity and agriculture and food systems.
My colleagues and I published the first global inventory for large solar energy-generating facilities in Nature. Large facilities are those that produce at least 10 kilowatts of solar energy when the sun shines at its peak. A typical residential rooftop installation can produce around 5 kilowatts.
To detect these features in satellite imagery, we built a machine-learning system and deployed it on more than 550 terabytes using several human lives of computing.
The map of all solar facilities as of 2018. (Kruitwagen et al, Nature, 2021)
We searched nearly half of the Earth's surface, filtering out remote locations far from humans. In total we detected 68,661 solar facilities. We can calculate the global installed generation capacity of 423 gigawatts by using the area and adjusting for uncertainty in our machine-learning system.
This figure is close to the International Renewable Energy Agency (IRENA's) estimate of 420 GW over the same period.
Monitoring the solar energy growth
Our study shows that solar PV generation capacity increased by an astonishing 81 percent between 2016-2018, the time period for which we had captured timestamped imagery. The growth was led by significant increases in India (184%), Turkey (143%), China (120%), and Japan (112 percent).
The facilities ranged from large, sprawling, gigawatt-scale installations in the deserts of Chile, South Africa and India, to industrial and commercial rooftop installations in California, Germany, rural patchwork installation in North Carolina, England, and urban patcheswork installations both in South Korea, Japan, and South Africa.
Benefits of facility-level data
Our country-level aggregates are very similar to IRENA's statistics at country level. These are gathered from questionnaires, officials of the country and industry associations. We address critical coverage gaps in countries with low electricity access, such as developing countries, which are not covered by other facility-level datasets.
Our data provide a common benchmark in both developed and developing countries.
Geospatially-localized data is of critical importance to the energy transition. To accurately determine the amount of electricity they generate or plan to generate, grid operators and participants in the electricity market must know exactly where solar facilities are located.
Remote systems and emerging in-situ systems can use location data to predict changes in generation, such as passing clouds or weather.
This predictability makes solar more likely to be a part of the overall energy mix. Solar will become more predictable and grid operators will have to reduce the number of fossil fuel power plants they keep in reserve. This will allow for more marginal projects to be unlocked.
We were able estimate the installation dates for 30% of these facilities by using the back catalog of satellite imagery. This data allows us to analyze the conditions that lead to the diffusion and can be used to help governments design better subsidies to promote faster growth.
Locations of solar facilities are more common than land use. Cropland was the most common. (Kruitwagen et al, Nature, 2021)
We can also study the unintended effects of the growth and expansion of solar energy generation by knowing where it is located. Our study revealed that solar power plants most commonly occur in agricultural areas. Grasslands and deserts follow.
This shows the importance of carefully considering the impacts that a tenfold increase in solar PV generating capacity over the next decade on food systems, biodiversity and lands used for vulnerable populations. Incentives can be provided by policymakers to encourage rooftop solar generation, which is less likely to cause land-use competition, and other renewable energy options.
Lucas Kruitwagen is a Climate Change and Artificial Intelligence Researcher at the University of Oxford.
This article was republished by The Conversation under Creative Commons. You can read the original article.