The rate of installation of solar and wind electricity generation needs to increase by a factor of more than five to reach net-zero emissions globally by 2060.
Electricity generation from solar and wind will be the central feature of a zero-carbon global energy system. Solar and wind generation have already reached large scale, with increasing rates of installation and falling costs. In 2019 solar and wind accounted for over 8% of global electricity generation[i]. However, much more is needed. The market for electricity will grow enormously as low carbon electricity replaces fossil fuels in many applications, and solar and wind will take a greatly increased share of this larger market.
So how much will solar and wind need to grow if the world is to reach net zero emissions by 2060?[ii]
I’ve estimated this by looking at three factors:
- Total final energy consumption (end use). This is assumed to be similar to 2019 levels of around 100,000 TWh p.a. (350 EJ p.a.) in the central case, with a sensitivity of 25% total growth.
- The proportion of energy consumptions that is met by electricity (including by hydrogen produced by electrolysis). This is assumed to be 80% in the central case, with a range 70-85%
- The proportion of electricity from solar and wind. This is also assumed to be 80% with a range 70-90%.
The basis for these assumptions is outlined at the end of this post.
The analysis implies that solar and wind will meet around two thirds of world energy demand by 2060. This is approximately 30 times the current total generation from these sources (see chart).
Chart: Composition of Global Energy Consumption
To reach this total, about 1,600 TWh p.a. of electricity generation from wind and solar needs to be added every year on average between now and 2060, more than five times the 2019 rate of growth of 300TWh[iii]. To reach this total by 2050 would require around seven times the current rate.
The multiple of current rates of installation needed for net-zero is shown in the table below, with the range corresponding to the range of assumptions noted above.
Table: Multiple of current installation rate for solar and wind necessary to reach net zero global emissions
| Central Case | Range | |
| Net zero by 2060 | 5 | 4 – 8 |
| Net zero by 2050 | 7 | 5 – 11 |
Most individual assumptions make little difference to these estimates, with estimates continuing to lie within the ranges shown. The most significant differences arise from variations in assumptions about the amount of biofuels, the amount of hydrogen made from natural gas with CCS, rather than by electrolysis, and to some extent amounts of nuclear and CCS in power generation, including the retrofit of CCS to existing power plants. Explicitly accounting for efficiency losses in making hydrogen from electrolysis would increase the need for wind and solar still further.
The main conclusion appears robust: a very large scale up of solar and wind, 4-11 times the current rate of installation, is required to enable of the huge switch away from fossil fuels necessary to eliminate emissions by around mid-century. This is broadly consistent with estimates by the International Renewable Energy Agency (IRENA) [iv].
Although the scale-up is very large, there do not appear to be any fundamental constraints preventing it. For example, the amount of land used for solar by 2060 would be enormous – about 0.4% of the earth’s land surface[v]. However this does not seem an insuperable barrier – for example it is much less than now used for agriculture. Other challenges include storage. Batteries and increasing interconnection are likely to reduce difficulties caused by variation in renewable output. It also seems likely that, as I’ve assumed, hydrogen will play a significant role as a storage medium to complement variable renewable electricity, especially for storage over weeks or months.
Meanwhile, continued increases in the scale of solar and wind generation, and consequent learning, will continue to reduce costs significantly. This will in turn greatly reduce the cost of the transition to net zero.
The need for such large growth implies continuing focus on policies to support the deployment of wind and solar electricity generation, including greatly expanded and enhanced electricity transmission grids. Other technologies will also be essential, but they all need to be developed in the context of the predominant role of wind and solar electricity generation.
Adam Whitmore – 14th December 2020
Assumptions
Total energy consumption in 2060
This refers to energy end use (final consumption), not primary energy, which includes among other things, large losses from using fossil fuels in power generation. I have here included electrolysis to make hydrogen as part of final consumption. If the efficiency losses from this process were added to final consumption as shown here the demand for wind and solar would be even greater.
The International Renewable Energy Agency (IRENA) has developed a scenario in which improvements in energy efficiency lead to demand being approximately constant or slightly falling over the period from now to 2050. There is potential for major efficiency gains, for example in replacing oil with electricity in the transport sector, increased use of heat pumps, and continuing energy efficiency gains in buildings. In contrast, as noted, there are losses in the production of hydrogen by electrolysis.
With such large opportunities for improved efficiency available, and with widespread international action to reduce emissions, I have assumed that something close to the scenario from IRENA is achievable, and that energy consumption in in 2060 will be around 102,000 terawatt hours per annum (370 EJ), a similar level to 2019.
Other data projections show consumption increasing by about 25%, and a sensitivity of 25% of additional consumption is also included for the upper end of the ranges shown.[vi]
Electricity as a proportion of energy.
Electricity consumption is assumed to increase by a factor of about three to four. Some of this electricity is used to make hydrogen, which acts as a form of energy transport and storage. The remaining energy use is concentrated in aviation and shipping, and some industrial processes. This is expected to be met from other sources, for example hydrogen made from fossil fuels with CCS (sometimes called blue hydrogen). Bio fuels will likely play an important role, but are likely to be limited among other things by the scale of available supply[vii]. They may well make their most valuable contribution in bio energy with CCS (BECCS), providing negative emissions.
I have excluded losses from transmission and distribution, which would increase further the amount of solar and wind required.
Wind and solar as a proportion of electricity.
I have then assumed that around 80% of electricity comes from wind and solar, with a range of 70%-90%. Other low carbon electricity sources account for the remaining 10-30%. This includes nuclear, which currently accounts for 10% of total electricity production, with output having fallen over the last decade[viii]. Hydro, which currently accounts for 16% of electricity generation, has grown over the last decade. I have assumed it cannot grow faster than this due to resource limitations. There may also significant amounts power generation from fossil fuels with post-combustion CCS. Other renewables such as geothermal are likely to account for only a small proportion of the total.
Nuclear may play a larger role than I’ve have assumed. However, it has very long lead times, is much more expensive than renewables and faces political obstacles in many jurisdictions. It seems unlikely to grow to dominate electricity production as it did in France in the 1980s and 1990s. CCS remains in the early stages of its deployment, but may play a significant role, for example in system balancing. There may also be substantial retrofit of existing plants, especially in Asia.
[i] https://ember-climate.org/data/global-electricity/
[ii] I have assumed net zero emissions could be achieved by 2060. This is the target date set by China, by far the world’s largest emitter. Some countries have committed to 2050, and this is examined as a sensitivity, but net zero seems less likely to be achieved by this date globally, especially as many countries have not yet committed to reaching net zero. See https://onclimatechangepolicydotorg.wordpress.com/2020/11/10/momentum-towards-net-zero-emissions-is-growing/
[iii] Source: BP Statistical Review of World Energy
[iv] This is broadly consistent with analysis by IRENA. This suggests a factor of six scale-up in renewables deployment is needed. However assumption differ. For example, IRENA in its analysis assumed 65% of energy will be supplied by renewable energy in 2050, but with a great proportion of renewables other than electricity. See: https://www.irena.org/-/media/Files/IRENA/Agency/Publication/2018/Apr/IRENA_Report_GET_2018.pdf and https://www.irena.org/publications/2019/Apr/Global-energy-transformation-A-roadmap-to-2050-2019Edition
[v] https://onclimatechangepolicydotorg.wordpress.com/2013/09/25/solar-deployment-are-there-limits-as-costs-come-down/ I’ve assumed 70kWh/m2 (a conservative assumption because it is based on data from older less efficient cells and much capacity will be based on newer more efficient technologies). This includes total site area (i.e. not only the panels). Generating 40,000TWh on this basis would require an area of around 570,000km2, about 0.4% of the world’s land surface of 149 million square km. This is a huge area – more than double the size of the United Kingdom of 242,000 km2 – although as noted probably an overestimate – and the true figure taking account of efficiency gains might be indicatively 30% less that this. It is in any case far less than the land devoted to agriculture, which uses solar energy to grow food. And solar power can often make use of spaces – such as rooftops and deserts – that have few alternative uses.
[vi] See https://eneroutlook.enerdata.net/forecast-world-final-energy-consumption.html
[vii] https://onclimatechangepolicydotorg.wordpress.com/2016/04/11/the-constrained-role-of-biomass/
[viii] Source: BP Statistical Review of World Energy
On Climate Change Policy 