Sunday, January 31, 2021

Imagining A New Energy Future

                                                                                                     written 24 January 2021

                                                                                                 published 31 January 2021



            My favorite Mendocino county beer is Anderson Valley Brewing Company's Boont amber.  They advertise as a "solar powered brewery", currently producing 40 percent of their electricity from the sun, and recently announced plans to expand to 100 percent.  The woman running the taproom said the contracts have been signed, the staff had been briefed on the new construction, and the system will include battery storage. 

            Their current solar system is probably grid tied, allowing excess production to be sold back to PG&E, while buying power when needed.  Over the last few decades, such net-metering has boosted the installation of solar arrays by using the grid to deal with renewable power intermittency.  About 20 percent of the electricity generated within California is currently produced by wind or sun, a percentage that is increasing rapidly as costs plummet due to increased efficiencies in the hardware and mass production.  Over the last decade, solar prices dropped 90 percent and wind dropped 70 percent, each now producing power at $40/MWh, making them the most cost-effective sources of new generation.  

            As renewable production grows, the mismatch between when power is produced, and when it is needed, is driving a boom in grid scale energy storage, primarily batteries at the moment.  There are three scales of mismatch to address: daily, seasonal, and year to year.  Batteries are great for addressing the daily day/night cycle, allowing rapid shift from charge to discharge, with a relatively small energy cost for the exchange.  Battery costs have been dropping faster than solar costs, and larger battery storage systems are being constructed every month, threatening to economically replace natural gas "peaker" plants for handling short term load changes.  But the seasonal winter/summer mismatch, and year to year changes, can't be handled with batteries.  This requires storing energy in a fundamentally different form, and the current best candidate is hydrogen.

            All combustion fuels, including carbohydrates in the bodies of humans and animals, firewood, coal, oil, and natural gas, have stored energy as hydrogen in chemical compounds.  The oxidation of hydrogen releases the stored energy into forms that can be utilized by living and social systems.  Oxidizing pure hydrogen releases only energy and water.  Oxidizing anything else produces additional carbon compound residues, which is why fossil fuel combustion is a climate problem.  Because hydrogen is so reactive, there is no free hydrogen, and it must be stripped out of a compound and stored.

            95 percent of the hydrogen produced today is generated from fossil fuels, which still creates the problematic carbon residues.  Hydrogen can be stripped from water using electricity, and if the electricity is from a renewable source, it is called green hydrogen, as it leaves no carbon residue.  The hydrogen must be compressed, or cooled, for efficient long-term storage, and all these steps require equipment and energy, reducing the overall efficiency of the energy stored.

            As humanity begins to deal with the reality of climate change, green hydrogen production and storage is becoming the next "new thing".  Trillions have already been committed in Europe, Japan, and Australia, which will dramatically reduce the cost of this hardware.  As with all renewable systems, the hardware is a scalable fixed cost, and the energy is free

            Now imagine if Anderson Valley Brewing Company wanted to become completely energy sufficient.  The solar array and battery storage must be large enough to handle their electrical needs in the winter minimum, so the summer excess could be converted to hydrogen.  This could be used for all their space heating needs throughout the year, as normal combustion appliances can be converted to burn hydrogen.  It would also supply all their brewing production heating needs.  Electricity needs beyond the array and battery system could be generated using a fuel cell or a hydrogen fueled gas turbine, or the brewery could remain connected to the grid.

            Mercedes, Nissan, Hyundai, Toyota, and Nikola, are all working on producing hydrogen fuel cell cars and trucks.  UPS and FedEx expect to shift to hydrogen.  The state of California is subsidizing hydrogen fueling stations.  Having electrical charging and hydrogen fueling available at the brewery would be an economic draw, not only for the brewery, but the entire Anderson valley.  Hydrogen production could use cheaper off-peak grid power, helping the overall economics of the grid.

            What a wonderful world this could be!