As noted previously, most commercial buildings utilize more electric and thermal energy than can be cost-effectively harvested, processed and stored from on-site renewable sources using present-day systems. Exceptions to this rule include abandoned airplane hangers, Mesoamerican pyramids, lunar bases, and strategically located terrestrial structures built and operated exclusively to prove a point.
There are then basically two options: purchase the additional energy required or generate it on-site. Typically thermal energy needs like chilled water, steam, or hot water are generated on-site from purchased fuel, and electrical energy needs are met by purchasing power from the grid. It is possible to purchase green or renewable power from the grid, although at the moment this action appears to fail Kant’s categorical imperative test: if everyone did it we’d be faced with a political, financial and physical impasse of non-trivial magnitude.
(Our grid at present requires a certain balance of energy generation types to function as it does. To generate all of our power from renewables tomorrow would require investments in infrastructure that would dilate the pupils of the even the most staunchest of Stimulus Advocates.)
Tabling for a moment the implications of an unlikely explosion in the demand for premium cost green power purchases, the present cost of renewable power is roughly 10% greater than “normal electricity”. And contrary to what is possibly a common belief, you probably don’t even get the green electrons you bought. The grid is a topic for another day, but suffice it to say that electrons are like a pack of over-caffeinated morning commuters in a [insert the name of your favorite densely populated metro area here] crosswalk: they follow the path of least resistance. When you buy green power you ensure it makes its way onto the grid somewhere, but if it is not generated in your specific area this may not reduce the need for grid improvements or additional power generation facilities in your neighborhood.
As such, renewable purchases are subject to the same grid losses and thermal inefficiencies as “conventional power”.
On-site electrical generation has the ability to reduce grid inefficiencies associated with a site’s energy use, to reduce a site’s overall emission contribution, and to reduce the cost of meeting the thermal energy needs through cogeneration. An assumption-laden chart will help to bear these points out. (Fine print to follow impression-making graphics.)
The emissions comparison for NOx and CO2 assume that the “Conventional Building” is heating with natural gas and utilizing grid average power. The cogeneration option is also based on natural gas. To estimate the atmospheric emissions for grid-purchased power in your area, visit this EPA site. If the base scenario were based on electric heat or a fuel of a more questionable post-combustion character, the spread would be greater.
The “Energy Expense” comparison assumes electricity costs $0.14/kWh and natural gas fuel costs $8.50/MMBtu. Maybe realistic, maybe not. Like a good building design, a good on-site generation system must be site specific and integrated with process needs. This is a comparison of operating costs only, and does not factor in the cost of capital or any other real world factors sure to make an actual project analysis cover a rich and varied emotional terrain.
By Michael Mark, PE
Engaging internet site:) Will come back
Mark,
Your points are well taken about the cost of implementing on-site passive sources vs. buying it direct from the grid. There are obviously pro’s and con’s to both concepts. (Pro) Buying direct from the utility spreads the risk, reduces capital cost, mitigates maintenance issues and a whole slue of headaches. (Con) Buying direct from utilities defers control to a regulated party where a business/institution removes themselves of the decision making processes. Personally, I believe the best way to take control of energy costs is to develop an energy consumption plan that implements a layered strategy. First and foremost, any large facility must determine it’s forbearance to pollution regulation and local/state/federal taxes. Based on their acceptance levels of their current situation they must then pursue their strategy. This would include:
1) Working with current energy providers to negotiate contractual obligations.
2) Look into rebates or cash reward incentives with energy providers and federal/state policy makers.
3) Weigh options for installing cogeneration energy on-site or renewable/passive energy. Obviously some options are more viable than others.
By taking this active approach to managing your energy you become a proactive player in the Corporate Social Responsible (CSR) arena. This can provide a competitive advantage over competition. CSR and reducing your company’s global footprint is a marketing departments dream. Imagine having the ability to sell a product with “made without the dependence of foreign oil”. This is a pretty powerful statement, especially in times like today. Not to mention having a plan to reduce energy consumption hedges the risk against the Cap and Trade concept which will “tax” U.S. businesses for carbon emissions. Either way you spin it, implementing a plan that manages the use of conventional energy sources by using methods like on-site energy or purchasing it from the local utility will help create a better and more sustainable organization for the future.