A solar thermochemical power plant using ammonia as an attractive option for greenhouse-gas abatement

The lack of effective means for energy storage and transport is often put forward as one of the major obstacles to the mass utilisation of solar energy. ANUʹs development of large paraboloidal solar collectors and a thermochemical heat-pipe transport concept could well be combined to offer an attractive solution to this problem. A 4-MWe solar-assisted natural gas power plant is under consideration for Tennant Creek in Northern Australia. This base-load power plant will employ a steam Rankine cycle power conversion unit and incorporate an array of 28 direct-steam-generating dishes with 400-m2 aperture each. A preliminary investigation of replacing its water/steam heat transfer network with an ammonia-based heat transfer system indicates that 24-hour storage could be provided at an additional cost of only 12%. Furthermore, for alternative sites with no natural gas back-up available, it was found that a thermochemical ammonia system could demonstrate 24-hour base-load solar power generation for the same per-dish capital cost as a solar-only steam system without storage. This opens the market to megawatt-size, remote, off-grid applications. Pollution and greenhouse-gas emissions from such a closed-loop solar power generation system would be zero.