Magnetocaloric Generator for Waste Heat Energy Recovery

A 2008 DOE report [1] indicated that up to 903 terrabtu per year of unrecovered low level industrial waste heat (IWH) in the US is available for conversion to electricity. Converting this heat to electricity at 30% conversion efficiency would produce ~9 GW of electric power, an equivalent to about 4.5 Hoover Dam outputs. Efficient low cost recovery of low level IWH at significant scale could displace a large number of fossil fuel power stations and avoid the concomitant production of CO2 as well as other greenhouse gases (GHG) and pollutants. Based on DOE target cost of $1/We, there is a potential $9B market for electricity generation from low level IWH. Traditional means for production of electricity from heat such as the steam cycle, organic Rankine cycle (ORC), Kalina cycle, all have efficiencies 20% from low level IWH. Alternative established technologies such as thermos electrics, thermionics, or piezo electrics are about an order of magnitude short of each of the DOE efficiency and cost targets. Aqwest proposes to develop a magnetocaloric generator (MCG) offering thermodynamic efficiency up to ~80% of Carnot limit, which enables ~30% conversion efficiency of low level of industrial waste heat (IWH) at 450ºF (232ºC) to electricity. In Phase I we assembled a bench scale demonstration MCG unit to map out the operating regime. During the process we invented a revolutionary solution that simultaneously enhances heat transfer, boosts performance, and reduces cost close to DOE targets. We developed a new design based on the new developments. In Phase II we will test validate the new heat transfer concept, implement is in the existing MCG demonstrator unit and test validate it. Using this data we will build a subscale prototype MCG with high fidelity to anticipated product. Key Words: Industrial waste heat, power generation, magnetocaloric, thermodynamic efficiency