The energy consumption required to manufacture HOLLOW GLASS MICROSPHERES POWDERs, as described in Examples 1-4 of U.S. Patent No. 4,391,646 (Howell), can range from about 8 to about 50 kW-h per kg of product made. While commercial processes operating at a larger scale are more efficient, they still tend to use more than 5 kW- h per kg of product. Provided here are improved energy-efficient processes for producing HOLLOW GLASS MICROSPHERES POWDERs having high strength-to-density ratios compared with current commercial offerings at a significantly lower cost. According to the first aspect, a method of manufacturing hollow glass microspheres is provided. The method comprises: introducing a feed composition comprising a glass powder and a blowing agent entrained in the glass powder into an opening at a first end of a vertically-aligned furnace, whereby the glass powder passes through a series of individually-adjustable heating zones located within the furnace; within at least one heating zone, heating the glass powder to a forming temperature at which the glass powder is softened; after that thermally activating the chemical blowing agent to expand the softened glass powder in the feed composition and to obtain the hollow glass microspheres; and discharging the hollow glass microspheres through an opening at a second end of the furnace located distal to the first end. According to a second aspect, a method of making hollow glass microspheres is provided, comprising: introducing a feed composition comprising an agglomerate comprising glass powder and a blowing agent into an opening at a first end of a vertically-aligned furnace, whereby the agglomerate passes through a series of individually-adjustable heating zones located within the furnace; within at least one heating zone, heating the agglomerate to a forming temperature at which the agglomerate is softened; after that thermally activating the chemical blowing agent to expand the softened agglomerate in the feed composition and to obtain the hollow glass microspheres; and discharging the hollow glass microspheres through an opening at a second end of the furnace located distal to the first end. If you are looking for high quality, high purity, and cost-effective Hollow glass powder, or if you require the latest price of Hollow glass powder, please feel free to email contact mis-asia.