I have been reading about the amount of energy that the cryptocurrency industry uses each year.  One source said that in the US, 25-50 million tons of carbon dioxide are emitted per year from cryptocurrency activity, which is about the same as the emissions from the diesel fuel used by all the railroads in the US.  Other sources say that global cryptocurrency activities use more energy than many countries use.  One cryptocurrency system has developed a protocol that significantly cuts energy use, but it is not clear if other systems will adopt similar protocols. 

In addition, significant amounts of computer hardware are discarded each year as bigger, faster computers are acquired to support cryptocurrency activities.  Significant energy and resources are required to build and then dispose of these computers and other hardware.  Along with considering the security of your money if you buy cryptocurrency (there have been some collapses of cryptocurrency companies recently), consider the environmental impact of cryptocurrency before you decide if cryptocurrency is right for you. 

There are many types of batteries and all of them contain materials that should be conserved through recycling.  In addition, many types of batteries are considered hazardous waste when disposed because of the harmful materials they contain.  However, most batteries can be recycled by appropriate facilities.  A quick safety tip before I tell you about battery recycling and disposal.  Keep batteries cool and put a piece of duct tape or electrical tape over the ends of the batteries when transporting them unless they are installed in a device.  Loose batteries can start a fire if they mix together in the wrong configuration.  In the US, many communities have a hazardous waste acceptance facility that will provide recycling or proper disposal for batteries.  Check with your local government for locations.  Two online organizations, Call2Recycle and Earth911 provide information on how and where to recycle batteries and other items.  A few bits of information on battery disposal:

• Rechargeable batteries can be recycled at some retail locations or at hazardous waste centers.  If the battery is not removable, take the entire device to the center. 
• Single-use batteries are safe to put in household trash but contain materials that can be recycled.  Most hazardous materials disposal centers will accept them.
• E-Bike batteries are accepted for recycling at many bike stores.
• Vehicle batteries are traditionally lead-acid batteries, so they contain significant amounts of lead and sulfuric acid.  Both are harmful to the environment (and people).  Return them to the store where you purchased them or drop them off at a hazardous waste collection center. 
  

According to the US Department of Energy, water heating accounts for about 20% of the energy use in your home.  There are many things that you can do to reduce the amount of hot water you use, but maintaining your water heater is also very important for saving energy.  There are many types of water heaters: demand or tankless, solar, and storage, to name a few.  A single-family storage water heater offers a ready reservoir -- from 20 to 80 gallons -- of hot water.  In the US, these storage water heaters are in wide use, although the tankless and solar water heaters are becoming more popular.  If you are selecting a new water heater, do some research on the various types to see which is best for you.  If you have an existing storage water heater, proper maintenance will help it perform more efficiently and last longer, both important in saving energy.  I found good how-to resources for storage and tankless water heater maintenance.  Also check the temperature setting for your hot water heater.  Most information sources recommend 120 degrees Fahrenheit so that the water is hot enough for most uses but uses less energy than higher temperature settings.  Temperature settings below 120 degrees Fahrenheit are not recommended for safety reasons. 

https://www.thisoldhouse.com/plumbing/21016402/how-to-maintain-a-water-heater

https://www.wikihow.com/Maintain-a-Tankless-Water-Heater