The evolution of MI members’ clean energy RD&D expenditures since 2015 is depicted in Fig. 1 based on reporting to the MI secretariat in Country Highlights reports3,4,5. Of MI’s 25 members, four (Chile, Mexico, the Netherlands and the UK) had already reached their goal of doubling by 2018, the latest reporting year for publicly available data from the MI secretariat. Additionally, twelve members were more than halfway to doubling their expenditures (that is, in 2018, their expenditures were at least 50% higher than in 2015), and seven members increased their expenditures, but by less than 50%. One country, Italy, reduced expenditures. Morocco joined MI in 2019 so their reporting data will be forthcoming next year.

Shown here are the expenditures reported by the countries to the MI Secretariat over time (in constant 2018 US$)3,4, compared to the initial pledged total5. The estimates are based on officially reported data to the MI Secretariat. Eight countries did not formally submit information on their progress to the MI Secretariat for at least one of the years: Australia in 2018, Austria in 2017 and 2018, Brazil in 2017 and 2018, Indonesia in 2017 and 2018, Mexico in 2018, South Africa in 2017 and 2018, United Arab Emirates in 2017 and 2018, and the US in 2016, 2017 and 2018. In these cases, we estimated the expenditure in two ways: IEA submissions based on the IEA RD&D database24 are used for IEA member countries (the US, Australia, Austria and Mexico); for non-IEA members, we used the previous year’s MI expenditure (that is, we assume no change in expenditure level). Additionally, the IEA RD&D database24 is used for the US clean energy RD&D estimate also for the baseline year, because the US baseline submission included expenditures on all energy RD&D, including fossil fuels. Values reported by member countries to MI in US$ were converted to constant 2018 US$, using conversion factors from the IEA.
China is on track to honour its pledge to double government RD&D spending on clean energy by 2020. This achievement is especially significant because of its scale: it will go from US$4 to US$8 billion, which will put its officially reported RD&D spending on clean energy on par or ahead of the United States.
US investments in clean energy RD&D increased by 42% between 2015 and 2020 from US$4.8 billion to US$6.8 billion in current dollars based on the DOE energy RD&D budget6. This is thanks to continued support from congressional appropriations even though the Trump administration proposed drastic cuts of more than 60% to clean energy RD&D every year in its budget request to Congress6.
While Germany has increased its public expenditures by nearly 50% between 2015 and 2018, the European Commission only reported a 15% increase between 2015 and 2018 for the EU as a whole. Japan increased its investments in clean energy RD&D by more than 50% by 20183,4,5. The European Union MI member countries achieved a 46% increase by 2018, and are not expected to have doubled their investment by 20203,4,5. The EU recently announced a major US$1 trillion battery initiative, however, that will dramatically increase its profile in clean energy RD&D in later years.
Changes in spending levels by the US government historically have been significant to global progress in clean energy because the United States was by far the largest public investor in global clean-energy RD&D2. With China’s pronounced increase in clean energy RD&D, the United States either has a rival or shares the global burden, depending on one’s perspective.
In the developing world, it is noteworthy that by 2018 both India and Brazil had increased their investments by 44% and 61% respectively. Both countries have also improved their internal reporting systems and harmonized their energy RD&D data to assure comparability. Mexico joined the International Energy Agency (IEA) in 2018, and officially started to report a detailed budget for energy RD&D expenditures for 2013 onwards.
Some may argue that the failure to attain the goal of doubling global funding for clean energy RD&D in five years undercuts MI’s usefulness, but we would disagree. In the first place, the goal of doubling investments may simply not have been practicable, and the fact that investments have increased 38% between 2015 and 2018 is certainly positive, if insufficient to honour the pledge of doubling by 2020.
But doubling investments was never the only goal. When countries negotiated the Paris Agreement, a predominant concern was the high technological cost of climate mitigation. Mission Innovation was intended to address such costs and thus became a crucial component of the Paris Agreement package. Costs for low-carbon energy technologies have fallen spectacularly since 2015. Between 2015 and 2020, for example, 60-cell monocrystalline solar photovoltaic (PV) module costs are estimated to have declined by 57%7. In onshore wind, where costs had already come down dramatically by 2015, unsubsidized levelized costs are estimated to have declined another 24% between 2015 and 20208. These cost declines spurred massive growth in deployment of renewable energy around the world. Installed capacity of solar installations in MI countries has risen 265% since 20159.
Moreover, almost all MI countries have made improvements to their national energy innovation systems. Demonstrable progress can be seen in output variables such as scientific publications and patent applications, even among developing countries. In Mexico, Brazil and Chile, for example, the number of scientific publications increased more than threefold for solar PV technologies between 2015 and 2019 (Fig. 2).

Data from Web of Science Citation Index Expanded.
Globally, overall green patent applications have declined since 201010, but patent applications for some types of clean energy grew between 2016 and 2019 during the MI period11. Specifically, patents grew for hydropower by 4%, geothermal by 11%, energy efficient technologies by 13% and wind by 65% in this period. More mature technologies experienced declines in patent applications, specifically 8% for nuclear. Solar experienced a pronounced decline of 45% between 2013–2016 but then a modest rise of 10% between 2016–2019. Green energy patents filings are concentrated in Japan, China, the United States, Germany and Korea. Altogether, these countries accounted for 76% of green patent applications in 201911. While additional analysis is needed to link these exact gains to the specific increase in RD&D spending under the MI mantel, prior research indicates a good correlation between RD&D spending and patent generation12,13,14.