Forging, Smelting, And Other Hot Industry

A considerable amount of industry and technology uses metals and other refined materials. From regular old steel to Carbon-Interlaced Aluminium Alloy, to carbon nanotubes to ceramic insulation on a warship, you need a lot of things heated up first before they can be worked.
And here's how.

Common methods

Blast and Arc furnace

Of course, there's the common, somewhat easy though comparatively inefficient method of blast furnaces and arc furnaces. It works well enough, and is quite common, but isn't the best option anymore. This method is useful because it's comparatively simple, and doesn't require that much of anything, beside electricity. Though, with the prevalence of Fusion power, a new method came to the forefront, in the 2080s.

Plasma forging

"What's the point of powering a forge with a fusion reactor, when the plasma inside the reactor is really hot already?" was the logic behind these sorts of furnaces. And it was pretty good. Still is. Even with a certain other option, this is the most common one even today. Basically, it consists of using a specialized fusion reactor, and funneling the plasma ever so slightly into a furnace, where it cools to around a few thousand degrees, from where it can be adjusted to what is necessary. Adjusting the carbon level in, say, steel is a bit tricky, but fortunately steel isn't that prevalent anymore, most things use either carbon-based materials, ceramics, or alloys of aluminium.

Solar forges

There's two main types of solar forges, planetside and in space. In space, these habitats, dedicated to smelting and refining metals and materials often get their raw material from some asteroid belt, and use the heat of the star to heat stuff up. They're often very close to a star, and have a lot of radiators and such. On the star-facing side, they have a lot of mirrors and panels, reflecting the heat into a central point. They can be in orbit of a planet, but being around a star allows better and more sunlight. That heat is then used to heat up furnaces and so on, also often doubling as a fine energy source. Planetside ones are much rarer, as clouds and night interfere with the light. But they are often more efficient, as a planet has much more space and surface area to use. Airless worlds have no clouds, and tidally locked planets like Ak'Thakra have never-ceasing sunlight. The Ak'Thakran Commonwealth in fact makes great use of these methods to smelt and manufacture Carbon-Interlaced Aluminium Alloy.

Antimatter forging

Comparatively rarer, due to the rarity of Antimatter, but still present, especially in core areas like the Core Worlds, as well as places like Ak'Thakra. This method essentially consists of feeding very small amounts of antimatter with very small amounts of matter to make heat. The main benefit is being compact, as you don't need a lot of antimatter, but the machinery is quite complex.