The total sum of carbon based energy, be it in the form of wood, coal, oil, methane, natural gas or biomass, originated from the sun. Photosynthesis captures sunlight and converts it to oxygen and reduced carbon forms. We see this in plant life. Plants give us oxygen, nutritional sustenance and fuel. In the distant past the cycle of plant life created carbon energy that has allowed humans to advance to the state we now enjoy. Fifty to sixty million years ago eastern Montana was home to a shallow swamp like environment. The jungle and forests were overlain with sediment, compressed over time and transformed into the coal that, through electrical generation, Bozeman illuminates its houses and streets with. The amount of energy the sun bestows upon earth in six months is equal to the collective reserves of all carbon based fuel sources.
Obviously we are a long way from harnessing sunlight in a cost effective and efficient manner. As we face dwindling carbon reserves and an atmosphere dramatically changed by the consumption of carbon fuel, harnessing energy from the sun a technological break-though that will benefit all humans. Will it happen in our lifetime? Chances are slim given the volatility and ease of transport for carbon based energy. Transitioning from one system to another will require massive capital expenditures. Given these challenges how do we as a society proceed? There are those that shy away from challenges and those that see it as an opportunity to try harder. Energy independence is one area that will require a fair amount of ingenuity, determination and perseverance. Success is ever more sweeter when the odds are against you.
Solar energy is currently harnessed by two methods: passive and solar. Aligning a building to have maximum southern exposure is an obvious example of passive collection. Active collection has principle methods: photovoltaic and thermal mass. Photovoltaic panels are constructed with silicon wafers that directly convert sunlight to electricity. Your calculator with a miniature cell is probably the most common form of this technology. Photovoltaic cells are between 12 – 20 % efficient, that is 80 % of the solar energy doesn’t convert to electricity. The current costs do not match the direct costs of electricity generated by coal. As efficiency increases with technological advancement photovoltaic collection will feature in our future energy mix.
Thermal mass captures sunlight in a manner that is transferred or stored without being converted into electrical current. The energy captured is typically used for low-temperature applications. The simplest form of thermal generation is a roof top solar water heater. The energy captured can be used in two ways that benefit daily energy usage: water usage and structure heating. Hot water from the roof heater is piped into or through the existing gas or electric water heater thereby reducing the energy load required to heat water to the desired temperature.
When designing new or retro fitting existing structures radiant heating is an efficient and comfortable way of warming interior spaces. Piping is plumbed into the floor and the warm liquid heats the structure from the ground up. By using the water from the roof top solar water heater the need to heat the water from carbon-based sources is lessened or entirely negated. Commercial and institutional applications stand to benefit from this technology.
Montanans are known for their ingenuity and perseverance. Encouraging solar thermal design and installation will bring us closer to the goal of energy independence. Making the transition to sustainable energy is a big step. If, like children, we start with small obtainable steps we’ll eventually make it.