Renewable energy is the foundational technology for net zero

We have already made great progress in developing sources of renewable energy - mostly solar and wind - but we still have a long way to go. Not only do we need to triple the size of our electrical energy systems, but we also need to ensure that we can cost-effectively store renewable (electrical) energy so that we no longer rely on fossil fuel generation to "fill the gaps" when renewable energy is not on line.

The table below shows indicative costs for various energy sources. In addition to these there is geothermal energy (which comes from the sub-surface of the earth; it is used for domestic heating and cooling and also for larger scale electricity generation in places where the geology is appropriate) and potentially ocean energy (most obviously, tidal and wave energy but there is also research into salinity gradient energy and conversion of ocean thermal energy).

Indicative costs of various energy sources

Figures from Bloomberg New Energy Finance
Seehere for an explanation of levelised cost.
Due to the carbon costs of construction, renewable power cannot be considered to be truly net zero.
TechnologyNotesLevelised cost $/MWh
(USA, 2020)*
Levelised cost $/MWh
(China, 2020)*
SolarPhotovoltaic cells convert solar energy directly into electricity. The sun's rays ca also be concentrated using mirrors and used to generate electricity in large-scale plants.32 - 5629 - 59
Large hydroHydropower derives from flowing water. Large scale hydro projects tend to create dams to store water for release when power is required. Small scale units typically do not interfere with water flow and are thus less controversial.42 - 84
Wind - offshoreWind power can be generated on land or offshore. Offshore causes fewer objections from local populations but is more expensive to install and maintain.26 - 5969 - 104
BioenergyBiomass incineration41 - 93
Wind - onshoreOnshore wind is cheaper than offshore wind26-5941 - 62
Wind - onshore + storageCost-effective storage is critical39 - 10655 - 116
Solar + storageCost-effective storage is critical44 - 15853 -176
CoalFOR COMPARISON60 - 15750 - 66
NuclearSmall-scale nuclear offers some promise and if we succeed with nuclear fusion, the possibilities open significantly though costs remain high193 - 34051 - 68
Utility scale battery Different costs for different durations from 1 to 4 hours136 - 211115 - 199

For many corporations increased reliance on renewable energy is an obvious first step in the transition to net zero. The organisation RE100 has been instrumental in securing pledges in this area which has provided a valuable boost to the renewable power market.

One of the biggest challenges that we face in this area is around storage. At the moment our ability to store renewable energy is under-developed such that the renewable content of a particular energy stream / grid can vary considerably depending upon hourly demand for electricity. Storage options include pumped hydro, hydrogen, various types of battery, thermal, flywheel and compressed air. Battery storage dominates for short-term (1-4 hour) power storage but the technology is not so applicable for longer-term storage - though this may change with the development of liquid metal batteries and other innovations.

As the variable cost of renewable energy approaches zero - the cheapest contract that has so far been struck for renewable power has been at a price of US$13.5/MWh for 2 GW of solar photovoltaic power in Abu Dhabi in April 2020 - the cost of renewable energy will approximate to the cost of storage (as opposed to production).

Bloomberg New Energy Finance forecsts for electricity generation in 2050

Bloomberg New Energy Finance (2020)
Peaker gas is gas that runs when there is very high demand for electricity.
Solar thermal is described here.
Energy generationExpected share by 2050
default scenario (%)
Expected share by 2050
2 degree scenario (%)
Coal12%3%
Gas17%7%
Peaker gas2%2%
Oil<1%0%
Nuclear7%5%
Hydro12%5%
Geothermal<1%<1%
Biomass1%1%
Onshore wind22%23%
Offshore wind4%9%
Utility-scale PV17%16%
Small-scale PV4%6%
Solar thermal0%1%
Other-20%