Sustainable Energy Technologies

Over the Horizon

Several important technologies await future refinement before they can be used
on a large scale.

Energy Storage and Batteries 

Energy storage is a core area of effort to make the energy grid more sustainable. Batteries have been the traditional way to capture and release electrical energy but are not yet sufficiently cost-effective for grid-scale storage. Long-duration energy-storage technologies like gravity, thermal, and mechanical storage aim to store energy without batteries, but scaling them remains a hurdle.

Batteries for long-duration energy storage need to be able to endure tens of thousands of capture-and-release cycles, retain charge over several hundreds of hours, and be made of inexpensive materials. Aqueous battery chemistries such as manganese-hydrogen batteries are more promising than Li-ion batteries from a cost perspective.

Renewable Fuels

Beyond storage, efforts are under way to deploy combustible fuels such as biodiesel and hydrogen that can be burned on demand but that are cleaner than traditional fossil fuels. Hydrogen, in particular, has been identified as a promising zero-carbon-emissions fuel source since its energy density by weight is three times that of fossil fuels. However, even in liquid or compressed-gas form (necessary for most transportation applications), hydrogen has a low energy density by volume— which means that a hydrogen fuel tank of a given size can carry much less energy than a gasoline fuel tank.

Finding cost-effective ways to produce hydrogen and carry it with acceptable leakage from production facilities to users is an additional challenge. Currently, it is sourced from fossil fuels through processes such as naphtha reforming, natural gas steam reforming, and coal gasification. Known as gray hydrogen, this conventional hydrogen has a significant carbon footprint and is not sustainable. Blue hydrogen, which is created from methane, and green hydrogen, which uses renewable electricity to generate hydrogen from water, are gaining attention because neither process emits greenhouse gases.

Carbon Capture and Removal

Carbon capture technologies work by capturing “new” carbon emissions produced by industrial processes or the burning of fossil fuels and then burying them, thereby preventing them from entering the atmosphere. Carbon removal refers to capturing “old,” or existing, carbon from the atmosphere. Both capture and removal are gaining research attention and could help users obtain some of the benefits of fossil fuels while minimizing carbon emissions.

Fusion

Fusion power continues to hold promise as a potentially limitless and inherently safe source of energy, but significant scientific and engineering breakthroughs are still needed to make it commercially viable. Commercial-scale fusion power plants are unlikely to play any important short-term role in reducing greenhouse gas emissions.

Grid Technologies

The future electric grid will be more extensive and complex than today’s version, with distributed power generation, consumption, and storage. Power sources will be largely decentralized. As electrical demand rises, grid capacity must expand significantly, potentially doubling or tripling in size and necessitating substantial infrastructure upgrades to manage larger and more variable energy flows. The future development of a “smart grid,” whose goal is to enhance efficiency, reliability, and resilience, will involve initiatives to replace old transmission lines with higher-performing ones, create vehicle-to-grid (V2G) systems that allow unused power from vehicle batteries to be fed to the grid, and deploy AI-driven energy systems to optimize grid operations and predict equipment failures.

REPORT PREVIEW: Sustainable Energy Technologies