While renewable energy is considered clean and sustainable, it can still produce some byproducts that offer disadvantages. One of those byproducts is hydrogen which is only released from water using electrolysis. The electrolysis process uses electricity to break down water molecules into hydrogen and oxygen. This process takes a lot of energy and generates a lot of heat which requires the use of costly cooling systems to keep the reaction temperatures within safe levels.
Hydrogen is an essential building block used in the industrial and food production industries. By contrast, in the electricity sector, utilities like wind and solar power use hydrogen as a byproduct of electricity production. Since it is a byproduct, it presents commercial challenges when using it. For example, wastewater heat recovery systems (WHRS) can only produce hydrogen using a catalytic reactor. This reactor requires expensive water cooling systems to keep the reaction temperatures safe. Since hydrogen is no longer used as a byproduct, the reactors are not being used properly. The WHRS is made to recover heat from water-cooled condensers at higher temperatures than the reactor. In other words, the cooling water system is not designed for high temperatures because it is intended for relatively cool condenser water.
Since hydrogen is a clean energy source, this research looks at using solar sources to produce hydrogen and the effect of using wood chips as the fuel source in this process. Solar energy can be converted into chemical energy in a photovoltaic cell and then used to split water (H2O) into oxygen (O2) and hydrogen (H2). It can then be released into the atmosphere through a water-cooled condenser. The temperature of this condenser is limited by Section 608 of the Federal Energy Administration Act, which limits it to around 0 degrees Celsius.
Experimenting With Wood Chips
First, a photovoltaic cell produced hydrogen by splitting water in a water-cooled condenser. The output of this process was 5 liters of hydrogen per hour, which was used in an electrolyzer to produce oxygen and hydrogen at temperatures up to 300 degrees Celsius. The wood chips were sourced from a local sawmill in Washington, USA (USA). Short pieces of wood simulate the process because they are renewable biomass, readily available, and transported quickly.
testing the concept
A photovoltaic cell was constructed using an LCD. The electricity produced by the PV cell was connected to a motor controller, DC motor, and direct current (DC) power supply to spin a cog in an open loop system. The gear/cog had an output of 0.5 Volts and was connected directly to a voltage doubler to produce 5 Volts at 1000 rpm from this system. It needed to be adjusted to function correctly with the PV power generating system.
A sample of wood chips is added to the gear/cog system. The wood chips are compacted into a small ball of sawdust. This system is then tested in the lab with and without wood chips added to test the effect on speed and output. It is found that hydrogen production increases when wood chips are used. The amount of time it took for hydrogen to be produced had also significantly reduced from 1 hour with no wood chips to 16 minutes with 2.5 grams of wood chips inside the gear/cog’s cog system.
testing the heat recovery system
A sample of wood chips is used to test the effect of wood chips in a WHRS with a condenser temperature of 0 degrees Celsius. The water temperature inside the condenser needed to be kept below 0 degrees Celsius, which meant that any additional energy source would need to be extremely cold or an expensive cooling system required to be used. The amount of heat that needs to be removed from this condenser depends on how much energy the solar cell and electrolyzer unit produces. In this experiment, 2.5 grams of wood chips were added inside a cog and placed directly into a water-cooled condenser.
The experiment was successful because it showed that wood chips significantly increased hydrogen production. It also presented disadvantages, such as the high cost of the air-cooled condenser used in hydrogen production, which is not applicable when wood chips are used. The amount of electricity required to produce hydrogen using this system is high. Once it reaches the limit where energy generated by solar panels and electrolyzer units has less than 500 Watts of heat per hour, an additional source, such as natural gas, is needed to produce more electricity.
