In considering these elements, it’s worth looking at the actual sources of emissions that this effort is intending to address. Most of it relates to onsite combustion for heating, transportation, or energy, as well as industrial and waste processes. Actual electrical generation is a small component (subset of 25% of electrical + heating) of these emissions.
This chart includes all greenhouse gas emissions, of which CO2 is cited as ~65%. In the U.S., as a proxy for developed markets, ~81% CO2 emissions as a share of GHGs, there are similar trends but electricity is ~27% of emissions and agriculture drops to 10%.
Therefore, many of the key questions should be directed around technologies supporting the replacement of onsite combustion-based processes (energy production for factories, heating, and other process sources) with non-emission on-site alternatives, or in facilitating the deployment and connection of these energy consumers to the electrical grid with electricity-based alternatives.
Many of the barriers to adoption require overcoming hurdles that are not directly technological breakthroughs (i.e., doing what’s never been done before; e.g., fusion reactor), but rather facilitating the rapid adoption and deployment of new technologies and architectures that address these needs. For example, the rapid conversion of vehicle fleets to EV would necessitate overcoming at least three logistical and supply chain issues:
The ability to build enough LIon batteries, which in turn requires efficient rare earth metal extractions or alternatives
Simultaneous conversion of electricity generation sources to non-emission alternatives. (example: [https://news.mit.edu/2019/lightweight-vehicle-electric-emissions-0826](https://news.mit.edu/2019/lightweight-vehicle-electric-emissions-0826)). One solution to this particular issue would be ambient superconductors @akb has mentioned, which could facilitate transporting energy from areas with abundant renewable production (e.g., solar in U.S. southwest or various wind power locations; also distribution of excess hydropower from Canada/Nordics/Chile/etc.) to areas of consumption and overcome grid congestion which is its own problem impacting generation and distribution
Sufficient charging stations and supporting grid distribution to replace the range and fast fueling times of petroleum-powered vehicles
Consumer and business adoption/acceptance of EV alternatives or of legislation requiring mass replacement of CO2-emitting vehicles
Global implementation of the above solutions
Given the extent of non-electrical energy in emissions, non-electrical/grid-based solutions likely need to be considered for many/most applications. Some may be replaceable with batteries, but given that a battery has ~32x the mass of a similar amount of petroleum, transporting fuel to sites is its own challenge. H2 checks a lot of boxes but requires safe storage, transport, and release/use mechanisms. Alternatively, one could look to make these solutions ‘as clean as possible’ (e.g., swap petroleum-based fuels for CH4, etc.) and make up the difference with investments in sequestration.
As such, a prize including the following requirements would address a majority of emissions sources (including possibly some relating to electrical generation if existing generators were converted to use this source; such a conversion would also avoid the lengthy process of installing new HV lines to move electricity from renewable producing areas to consuming areas):
Joules per kg density similar to or better than petroleum
Emissions-less (or emissions-lite if balancing with sequestration) consumption
Abundant and emissions-less production
Safe and economical transport and storage
Economical production/ of consumption units/replacement of existing units
Feasibility of rapidly scaling production and deployment of consumption units