Current World Power Production
Today, more than 90% of the world’s electrical power is generated from heat in one way or another. Heat engines are the devices that handle the electrical conversion process. Steam turbines are the most common examples of heat engines. A heat source (usually coal or fuel) is burned to boil water, causing pressurized steam – like steam escaping from a pressure cooker valve – that spins a turbine. The mechanical energy of the spinning turbine is converted into electricity.
Thermophotovoltaic Cells
Thermophotovoltaic (TPV) cells are another type of engine that is powered by heat. They use semiconducting materials to directly convert the photons from a heat source into electricity. Like solar photovoltaic cells, thermophotovoltaic cells have no moving parts, which makes them cheaper to maintain than steam turbines. They can also convert higher temperature heat than steam turbines, which increases their efficiency. However, TPV cells traditionally haven’t been as efficient as the steam turbines, converting just 20% of the heat energy to electricity compared to steam turbines’ 35%.
Renewable Energy Sources
And though we know that renewable energy sources are better for the environment than using fossil fuels are, we still rely on coal, fuel oils and natural gas to produce two-thirds of the world’s electricity. Largely because those sources of heat are more accessible and reliable, i.e. we can burn more fuel, but we can’t make the sun shine or the wind blow. An additional problematic issue with renewable energy sources was the temporary storage of excess generated power in batteries. Because traditional batteries lose charge over time, the storage only lasted days or weeks. That meant we couldn’t bank a ton of solar power from the summer to use in winter.
40% Efficiency
But now, a different kind of heat engine has been developed by researchers at MIT and the National Renewable Energy Laboratory (NREL). A heat engine that’s overtaken the efficiency of steam engines, potentially transforming how we produce electrical energy. It began when MIT researchers calculated that getting the efficiency rate of TPV cells up to 35% would make them commercially viable and competitive with other heat engines. And with the help of NREL scientists, they designed a thermophotovoltaic cell that can convert heat up to 4,350 degrees Fahrenheit into electricity with about 40% efficiency!
Geothermic Power Production
The key to the researchers success was using many layers of different semiconductors materials. Some of the semiconductors some absorb photons in mostly visible and ultraviolet wavelengths, while others absorb infrared. A gold-plated mirror in the cell reflects any unabsorbed photons back to the heat source to minimize waste. This development in thermophotovoltaic technology is most promising for geothermic power production.
Power Under Our Feet
Traditional geothermal power production taps into a vastly under-utilized heat source to run heat engines that generate electricity, one quite literally right under our feet. The Earth’s core. It’s extremely hot and there are many areas where the molten sub-surface is very near the surface, such as the Pacific Ocean’s volcanic ‘ring-of-fire‘ and Yellowstone Park in the USA.
Another Type Of Steam Engine
Geothermal power production involves the use of near-surface heat layers to bring fluids to a boiling state in order to generate steam that’s then used to turn electrical generating turbines – another type of steam turbine. There are already many nations such as the USA, Japan, Philippines, etc., that use geothermal heat to power steam engines to generate electricity. But, the plants are few and provide just a small amount of national power needs due to current technological inefficiencies, a lack of research funding and energy market protections.
Transforming Geothermic Power Production
However, being able to place banks or shafts of TPV cells directly down into thermally active areas will transform geothermal power production, allowing the commercial production of abundant electricity continuously year round with far less equipment, maintenance, repair costs and environmental impact. And the use of advanced electrical storage systems, such as Tesla’s battery megapacks being used in San Francisco, now make thermophotovoltaic power generated power storage for metropolitan areas very viable, sensible and doable.
No New Infrastructure Needed
And the next best news is that all of the geothermal power that can be generated by thermophotovoltaic cells can go directly into the existing electrical grid, requiring no new electrical infrastructure. So, kudos and congrats to the folks at the Massachusetts Institute of Technology and the US National Renewable Energy Laboratory for outstanding work that helps us to build a better world for us all.
