The Solar Resource
When compared to conventional energy reserves, the global solar resource is seen to be unimaginably large, so large that even graphics like the one shown below don’t give an accurate visualization. If the total annual world consumption of primary energy resources were represented by a one-centimeter diameter circle—roughly as shown below—a linearly scaled representation of the solar energy falling on Earth’s land surfaces each year would be a circle nearly 15 meters in diameter. On the other hand, with that same one-centimeter baseline representing world energy consumption, the combination of all fossil fuel reserves would be a circle roughly 1 meter in diameter, or enough for roughly another century. So even if we keep using coal, oil, and natural gas at current rates, we’re not going to run out anytime soon, and we always seem to be finding new fossil fuel reserves or new ways to exploit reserves that we previously thought were inaccessible. As you’ve probably heard before, the Stone Age didn’t end because we ran out of rocks. It ended because our ancestors found better ways of doing things.
Global Energy Potential by Resource
The sheer magnitude of the solar resource is impressive, but the fact that it’s distributed so uniformly across Earth’s surface is even more amazing. The maps below show that there’s only about a factor of two difference between the integrated annual solar irradiance in sparsely populated desert regions and in the more temperate regions where most of us live. When averaged over yearly time frames, there’s more than enough solar energy to meet all of our energy needs, and every nation on earth has a sizable share of the huge solar resource.
From the figures above, we can begin to appreciate the magnitude of the solar resource and we can see that it’s quite uniformly distributed across the globe. These are positive features we can build on to make solar a useful, even dominant, primary energy resource. But there is another characteristic of the solar resource which has, in the past, presented a major problem. The problem is this: the amount of sunlight incident at any particular location on the earth’s surface is notoriously variable—on hourly, daily, and seasonal time scales. Our modern societies use energy, and lots of it, even when the sun isn’t shining. Efficiently collecting solar radiation and converting it into the types of energy we use are not enough. To make solar a viable primary energy resource, we also have to store the energy that we derive from sunlight, and some of that energy has to be stored for the long term, from season to season.
But there is good news on energy storage front. Just consider for a moment the two types of energy produced by our SEA Cogeneration System (SEA Cogen): low-grade thermal energy and electricity. The valuable low-grade thermal energy produced by our systems can be efficiently stored for the long term by using a proven technology that’s been around for quite some time: Borehole Seasonal Thermal Energy Storage (BSTES). The publication found at DLSC reports Coefficient of Performance values in excess of 30 for a mature residential BSTES system. With this technology, it’s easy to store the thermal energy produced by SEA’s cogeneration systems. And after a period of storage, that energy can be efficiently reclaimed as needed for a variety of applications in our homes, businesses, and industries, including applications which will result in the displacement of roughly 40% of the electricity we now generate.
Historically, storage of electrical energy has been a serious problem. But there is good news on this front as well. Recent technology developments have made batteries a convenient, efficient, and reliable option for storing the electricity needed to bridge short-term (hourly, daily) variations of the solar resource. But batteries are far too expensive for storing the large quantities of energy required to bridge seasonal variations of the solar resource.
Now the problem of seasonal storage of electricity—solar’s final impediment—has been eliminated. During the past few years, water electrolysis units with efficiencies in excess of 80 per cent have become commercially available. Electricity generated by SEA’s cogeneration system can power these electrolysis units to produce hydrogen gas. The hydrogen can then be converted to a hydrogen-rich fuel such as ammonia which is convenient to store and transport (Proton Ventures). These fuels can be stored indefinitely and then, when their energy is needed, they can be burned in SEA’s high-efficiency engines (SEA Engine). Our engines can be used to drive electric generators, thereby re-generating a large fraction of the solar-derived electricity that was used in the water electrolysis processes that created the fuels.
The solar value chain is now complete. SEA’s cogeneration system can efficiently collect solar radiation and cost-effectively convert it into valuable low grade thermal energy and electricity. The thermal energy can be stored on seasonal time scales by using proven BSTES technology. The electricity can either be used directly as it is generated, stored in batteries for the short term, or converted to hydrogen-rich fuels that can be stored for weeks or months until the stored energy is needed as electricity. The electricity can then be regenerated by burning the fuels in SEA’s high efficiency engine.
When existing electrolysis, battery, chemical, and thermal storage technologies are integrated on a broad scale with SEA’s cogeneration systems and our high-efficiency engines, we will achieve the age-old dream of harnessing the power of the sun; and every person living on planet Earth will experience life-changing social, economic, environmental, and security benefits that can be sustained and passed on to future generations.