No policy or instrument does this well today. SPARC does it gradually, and on evidence.
Governments have committed to lower emissions, and the power sector carries much of that load. Most of its emissions come from fossil plants that already exist, many of them under contracts that run for decades.
Those cuts have to come without risking a reliable grid or raising the cost of electricity. New renewables help, but they are added alongside the fossil fleet, not instead of it.
A fossil power contract gives its plant rights for decades: to generate, to be paid and, with that, to emit. Investors financed the plant on those rights.
Policy can change direction. It cannot simply take those rights away without legal disputes, higher costs for electricity customers and a weaker investment climate.
Governments need four things at once: lower emissions from the plants already running, a reliable grid, affordable electricity and respect for existing contracts.
Each tool in use today delivers some of these. None was built to deliver all four.
Closing plants early has been the main route. Even with real money and effort behind it, the flagship deal did not close.
A buyout must pay for every remaining contract year, up front, before a single tonne is avoided.
SPARC works inside the contract instead of ending it. It starts with one share of one contract and grows step by step, instead of waiting for one deal on the whole plant.
Payment follows delivery, and every carbon claim rests on metered MWh. The evidence comes first, not a model of what might happen.